Commit Graph

250 Commits

Author SHA1 Message Date
Brian Behlendorf
6954c22f35
Use fallthrough macro
As of the Linux 5.9 kernel a fallthrough macro has been added which
should be used to anotate all intentional fallthrough paths.  Once
all of the kernel code paths have been updated to use fallthrough
the -Wimplicit-fallthrough option will because the default.  To
avoid warnings in the OpenZFS code base when this happens apply
the fallthrough macro.

Additional reading: https://lwn.net/Articles/794944/

Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #12441
2021-09-14 10:17:54 -06:00
Tony Nguyen
6bc61d22c4
Run arc_evict thread at higher priority
Run arc_evict thread at higher priority, nice=0, to give it more CPU
time which can improve performance for workload with high ARC evict
activities.

On mixed read/write and sequential read workloads, I've seen between
10-40% better performance.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Tony Nguyen <tony.nguyen@delphix.com>
Closes #12397
2021-08-10 11:36:26 -06:00
Mark Johnston
da27b8bc7f Initialize "autoreplace" in spa_ld_get_props()
spa_prop_find() may fail to find the specified property, in which case
it suppresses ENOENT from zap_lookup().  In this case, the return value
is left uninitialized, so spa_autoreplace was being initialized using an
uninitialized stack variable.

This was found using KMSAN.  It appears to be a regression from commit
9eb7b46ed0, which removed the initialization of "autoreplace" from the
definition.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Mark Johnston <markj@FreeBSD.org>
Closes #12383
2021-07-26 11:53:47 -07:00
Alexander Motin
1b50749ce9
Optimize allocation throttling
Remove mc_lock use from metaslab_class_throttle_*().  The math there
is based on refcounts and so atomic, so the only race possible there
is between zfs_refcount_count() and zfs_refcount_add().  But in most
cases metaslab_class_throttle_reserve() is called with the allocator
lock held, which covers the race.  In cases where the lock is not
held, GANG_ALLOCATION() or METASLAB_MUST_RESERVE are set, and so we
do not use zfs_refcount_count().  And even if we assume some other
non-existing scenario, the worst that may happen from this race is
few more I/Os get to allocation earlier, that is not a problem.

Move locks and data of different allocators into different cache
lines to avoid false sharing.  Group spa_alloc_* arrays together
into single array of aligned struct spa_alloc spa_allocs.  Align
struct metaslab_class_allocator.

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Don Brady <don.brady@delphix.com>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored-By: iXsystems, Inc.
Closes #12314
2021-07-21 06:40:36 -06:00
Brian Behlendorf
88a4833039
Update cache file when setting compatibility property
Unlike most other properties the 'compatibility' property is stored
in the pool config object and not the DMU_OT_POOL_PROPS object.

This had the advantage that the compatibility information is available
without needing to fully import the pool (it can be read with zdb).
However, this means we need to make sure to update both the copy of
the config in the MOS and the cache file.  This wasn't being done.

This commit adds a call to spa_async_request() to ensure the copy of
the config in the cache file gets updated as well as the one stored
in the pool.  This same change is made for the 'comment' property
which suffers from the same inconsistency.

Reviewed-by: Sean Eric Fagan <sef@ixsystems.com>
Reviewed-by: Colm Buckley <colm@tuatha.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #12261 
Closes #12276
2021-06-24 14:30:02 -07:00
Rich Ercolani
8e739b2c9f
Annotated dprintf as printf-like
ZFS loves using %llu for uint64_t, but that requires a cast to not 
be noisy - which is even done in many, though not all, places.
Also a couple places used %u for uint64_t, which were promoted
to %llu. 

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #12233
2021-06-22 21:53:45 -07:00
Alexander Motin
29274c9f6d
Optimize small random numbers generation
In all places except two spa_get_random() is used for small values,
and the consumers do not require well seeded high quality values.
Switch those two exceptions directly to random_get_pseudo_bytes()
and optimize spa_get_random(), renaming it to random_in_range(),
since it is not related to SPA or ZFS in general.

On FreeBSD directly map random_in_range() to new prng32_bounded() KPI
added in FreeBSD 13.  On Linux and in user-space just reduce the type
used to uint32_t to avoid more expensive 64bit division.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored-By: iXsystems, Inc.
Closes #12183
2021-06-22 17:35:23 -06:00
Alexander Motin
7457b024ba
Scale worker threads and taskqs with number of CPUs
While use of dynamic taskqs allows to reduce number of idle threads,
hardcoded 8 taskqs of each kind is a big overkill for small systems,
complicating CPU scheduling, increasing I/O reorder, etc, while
providing no real locking benefits, just not needed there.

On another side, 12*8 worker threads per kind are able to overload
almost any system nowadays.  For example, pool of several fast SSDs
with SHA256 checksum makes system barely responsive during scrub, or
with dedup enabled barely responsive during large file deletion.

To address both problems this patch introduces ZTI_SCALE macro, alike
to ZTI_BATCH, but with multiple taskqs, depending on number of CPUs,
to be used in places where lock scalability is needed, while request
ordering is not so much.  The code is made to create new taskq for
~6 worker threads (less for small systems, but more for very large)
up to 80% of CPU cores (previous 75% was not good for rounding down).
Both number of threads and threads per taskq are now tunable in case
somebody really wants to use all of system power for ZFS.

While obviously some benchmarks show small peak performance reduction
(not so big really, especially on systems with SMT, where use of the
second threads does not give as much performance as the first ones),
they also show dramatic latency reduction and much more smooth user-
space operation in case of high CPU usage by ZFS.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored-By: iXsystems, Inc.
Closes #11966
2021-05-14 09:13:53 -07:00
pstef
458f82319a
Balance parentheses in parameter descriptions
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Piotr Paweł Stefaniak <pstef@freebsd.org>
Closes #11882
2021-04-11 16:35:07 -07:00
Andrea Gelmini
bf169e9f15 Fix various typos
Correct an assortment of typos throughout the code base.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Closes #11774
2021-04-02 18:52:15 -07:00
Colm
658fb8020f
Add "compatibility" property for zpool feature sets
Property to allow sets of features to be specified; for compatibility
with specific versions / releases / external systems. Influences
the behavior of 'zpool upgrade' and 'zpool create'. Initial man
page changes and test cases included.

Brief synopsis:

zpool create -o compatibility=off|legacy|file[,file...] pool vdev...

compatibility = off : disable compatibility mode (enable all features)
compatibility = legacy : request that no features be enabled
compatibility = file[,file...] : read features from specified files.
Only features present in *all* files will be enabled on the
resulting pool. Filenames may be absolute, or relative to
/etc/zfs/compatibility.d or /usr/share/zfs/compatibility.d (/etc
checked first).

Only affects zpool create, zpool upgrade and zpool status.

ABI changes in libzfs:

* New function "zpool_load_compat" to load and parse compat sets.
* Add "zpool_compat_status_t" typedef for compatibility parse status.
* Add ZPOOL_PROP_COMPATIBILITY to the pool properties enum
* Add ZPOOL_STATUS_COMPATIBILITY_ERR to the pool status enum

An initial set of base compatibility sets are included in
cmd/zpool/compatibility.d, and the Makefile for cmd/zpool is
modified to install these in $pkgdatadir/compatibility.d and to
create symbolic links to a reasonable set of aliases.

Reviewed-by: ericloewe
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Colm Buckley <colm@tuatha.org>
Closes #11468
2021-02-17 21:30:45 -08:00
Will Andrews
f4f50a7048
spa_export_common: refactor common exit points
Create a common exit point for spa_export_common (a very long 
function), which avoids missing steps on failure.  This work
is helpful for the planned forced pool export changes.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by:	Will Andrews <will@firepipe.net>
Closes #11514
2021-01-25 15:04:11 -08:00
Matthew Ahrens
aa755b3549
Set aside a metaslab for ZIL blocks
Mixing ZIL and normal allocations has several problems:

1. The ZIL allocations are allocated, written to disk, and then a few
seconds later freed.  This leaves behind holes (free segments) where the
ZIL blocks used to be, which increases fragmentation, which negatively
impacts performance.

2. When under moderate load, ZIL allocations are of 128KB.  If the pool
is fairly fragmented, there may not be many free chunks of that size.
This causes ZFS to load more metaslabs to locate free segments of 128KB
or more.  The loading happens synchronously (from zil_commit()), and can
take around a second even if the metaslab's spacemap is cached in the
ARC.  All concurrent synchronous operations on this filesystem must wait
while the metaslab is loading.  This can cause a significant performance
impact.

3. If the pool is very fragmented, there may be zero free chunks of
128KB or more.  In this case, the ZIL falls back to txg_wait_synced(),
which has an enormous performance impact.

These problems can be eliminated by using a dedicated log device
("slog"), even one with the same performance characteristics as the
normal devices.

This change sets aside one metaslab from each top-level vdev that is
preferentially used for ZIL allocations (vdev_log_mg,
spa_embedded_log_class).  From an allocation perspective, this is
similar to having a dedicated log device, and it eliminates the
above-mentioned performance problems.

Log (ZIL) blocks can be allocated from the following locations.  Each
one is tried in order until the allocation succeeds:
1. dedicated log vdevs, aka "slog" (spa_log_class)
2. embedded slog metaslabs (spa_embedded_log_class)
3. other metaslabs in normal vdevs (spa_normal_class)

The space required for the embedded slog metaslabs is usually between
0.5% and 1.0% of the pool, and comes out of the existing 3.2% of "slop"
space that is not available for user data.

On an all-ssd system with 4TB storage, 87% fragmentation, 60% capacity,
and recordsize=8k, testing shows a ~50% performance increase on random
8k sync writes.  On even more fragmented systems (which hit problem #3
above and call txg_wait_synced()), the performance improvement can be
arbitrarily large (>100x).

Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Don Brady <don.brady@delphix.com>
Reviewed-by: Mark Maybee <mark.maybee@delphix.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #11389
2021-01-21 15:12:54 -08:00
Alexander Motin
f8020c9363
Make metaslab class rotor and aliquot per-allocator.
Metaslab rotor and aliquot are used to distribute workload between
vdevs while keeping some locality for logically adjacent blocks.  Once
multiple allocators were introduced to separate allocation of different
objects it does not make much sense for different allocators to write
into different metaslabs of the same metaslab group (vdev) same time,
competing for its resources.  This change makes each allocator choose
metaslab group independently, colliding with others only sporadically.

Test including simultaneous write into 4 files with recordsize of 4KB
on a striped pool of 30 disks on a system with 40 logical cores show
reduction of vdev queue lock contention from 54 to 27% due to better
load distribution.  Unfortunately it won't help much ZVOLs yet since
only one dataset/ZVOL is synced at a time, and so for the most part
only one allocator is used, but it may improve later.

While there, to reduce the number of pointer dereferences change
per-allocator storage for metaslab classes and groups from several
separate malloc()'s to variable length arrays at the ends of the
original class and group structures.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Closes #11288
2020-12-15 10:55:44 -08:00
Paul Dagnelie
60a4c7d2a2
Implement memory and CPU hotplug
ZFS currently doesn't react to hotplugging cpu or memory into the 
system in any way. This patch changes that by adding logic to the ARC 
that allows the system to take advantage of new memory that is added 
for caching purposes. It also adds logic to the taskq infrastructure 
to support dynamically expanding the number of threads allocated to a 
taskq.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Matthew Ahrens <matthew.ahrens@delphix.com>
Co-authored-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes #11212
2020-12-10 14:09:23 -08:00
Ryan Moeller
0aacde2e9a
FreeBSD: notify userspace when a vdev is removed
This is needed for zfsd to autoreplace vdevs.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #11260
2020-12-02 10:20:02 -08:00
Brian Behlendorf
b2255edcc0
Distributed Spare (dRAID) Feature
This patch adds a new top-level vdev type called dRAID, which stands
for Distributed parity RAID.  This pool configuration allows all dRAID
vdevs to participate when rebuilding to a distributed hot spare device.
This can substantially reduce the total time required to restore full
parity to pool with a failed device.

A dRAID pool can be created using the new top-level `draid` type.
Like `raidz`, the desired redundancy is specified after the type:
`draid[1,2,3]`.  No additional information is required to create the
pool and reasonable default values will be chosen based on the number
of child vdevs in the dRAID vdev.

    zpool create <pool> draid[1,2,3] <vdevs...>

Unlike raidz, additional optional dRAID configuration values can be
provided as part of the draid type as colon separated values. This
allows administrators to fully specify a layout for either performance
or capacity reasons.  The supported options include:

    zpool create <pool> \
        draid[<parity>][:<data>d][:<children>c][:<spares>s] \
        <vdevs...>

    - draid[parity]       - Parity level (default 1)
    - draid[:<data>d]     - Data devices per group (default 8)
    - draid[:<children>c] - Expected number of child vdevs
    - draid[:<spares>s]   - Distributed hot spares (default 0)

Abbreviated example `zpool status` output for a 68 disk dRAID pool
with two distributed spares using special allocation classes.

```
  pool: tank
 state: ONLINE
config:

    NAME                  STATE     READ WRITE CKSUM
    slag7                 ONLINE       0     0     0
      draid2:8d:68c:2s-0  ONLINE       0     0     0
        L0                ONLINE       0     0     0
        L1                ONLINE       0     0     0
        ...
        U25               ONLINE       0     0     0
        U26               ONLINE       0     0     0
        spare-53          ONLINE       0     0     0
          U27             ONLINE       0     0     0
          draid2-0-0      ONLINE       0     0     0
        U28               ONLINE       0     0     0
        U29               ONLINE       0     0     0
        ...
        U42               ONLINE       0     0     0
        U43               ONLINE       0     0     0
    special
      mirror-1            ONLINE       0     0     0
        L5                ONLINE       0     0     0
        U5                ONLINE       0     0     0
      mirror-2            ONLINE       0     0     0
        L6                ONLINE       0     0     0
        U6                ONLINE       0     0     0
    spares
      draid2-0-0          INUSE     currently in use
      draid2-0-1          AVAIL
```

When adding test coverage for the new dRAID vdev type the following
options were added to the ztest command.  These options are leverages
by zloop.sh to test a wide range of dRAID configurations.

    -K draid|raidz|random - kind of RAID to test
    -D <value>            - dRAID data drives per group
    -S <value>            - dRAID distributed hot spares
    -R <value>            - RAID parity (raidz or dRAID)

The zpool_create, zpool_import, redundancy, replacement and fault
test groups have all been updated provide test coverage for the
dRAID feature.

Co-authored-by: Isaac Huang <he.huang@intel.com>
Co-authored-by: Mark Maybee <mmaybee@cray.com>
Co-authored-by: Don Brady <don.brady@delphix.com>
Co-authored-by: Matthew Ahrens <mahrens@delphix.com>
Co-authored-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Mark Maybee <mmaybee@cray.com>
Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #10102
2020-11-13 13:51:51 -08:00
Brian Behlendorf
d0249a4bd0
Replace ZFS on Linux references with OpenZFS
This change updates the documentation to refer to the project
as OpenZFS instead ZFS on Linux.  Web links have been updated
to refer to https://github.com/openzfs/zfs.  The extraneous
zfsonlinux.org web links in the ZED and SPL sources have been
dropped.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #11007
2020-10-08 20:10:13 -07:00
Ryan Moeller
4d55ea811d
Throw const on some strings
In C, const indicates to the reader that mutation will not occur.
It can also serve as a hint about ownership.

Add const in a few places where it makes sense.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Closes #10997
2020-10-02 17:44:10 -07:00
George Wilson
c494aa7f57
vdev_ashift should only be set once
== Motivation and Context

The new vdev ashift optimization prevents the removal of devices when
a zfs configuration is comprised of disks which have different logical
and physical block sizes. This is caused because we set 'spa_min_ashift'
in vdev_open and then later call 'vdev_ashift_optimize'. This would
result in an inconsistency between spa's ashift calculations and that
of the top-level vdev.

In addition, the optimization logical ignores the overridden ashift
value that would be provided by '-o ashift=<val>'.

== Description

This change reworks the vdev ashift optimization so that it's only
set the first time the device is configured. It still allows the
physical and logical ahsift values to be set every time the device
is opened but those values are only consulted on first open.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Cedric Berger <cedric@precidata.com>
Signed-off-by: George Wilson <gwilson@delphix.com>
External-Issue: DLPX-71831
Closes #10932
2020-09-18 12:13:47 -07:00
Pavel Snajdr
c95625769d Fix stack frame size: spa_livelist_delete_cb()
Reviewed-by: Ryan Moeller <freqlabs@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Pavel Snajdr <snajpa@snajpa.net>
Closes #10879
2020-09-15 15:55:03 -07:00
Matthew Macy
7432d29760
FreeBSD: reduce priority of ZIO_TASKQ_ISSUE writes by a larger value
On FreeBSD, if priorities divided by four (RQ_PPQ) are equal then
a difference between them is insignificant. In other words,
incrementing pri by only one as on Linux is insufficient.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #10872
2020-09-04 11:13:27 -07:00
Don Brady
4f07282786
Avoid posting duplicate zpool events
Duplicate io and checksum ereport events can misrepresent that 
things are worse than they seem. Ideally the zpool events and the 
corresponding vdev stat error counts in a zpool status should be 
for unique errors -- not the same error being counted over and over. 
This can be demonstrated in a simple example. With a single bad 
block in a datafile and just 5 reads of the file we end up with a 
degraded vdev, even though there is only one unique error in the pool.

The proposed solution to the above issue, is to eliminate duplicates 
when posting events and when updating vdev error stats. We now save 
recent error events of interest when posting events so that we can 
easily check for duplicates when posting an error. 

Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Don Brady <don.brady@delphix.com>
Closes #10861
2020-09-04 10:34:28 -07:00
Matthew Ahrens
3808032489
nowait synctask must succeed
If a `zfs_space_check_t` other than `ZFS_SPACE_CHECK_NONE` is used with
`dsl_sync_task_nowait()`, the sync task may fail due to ENOSPC.
However, there is no way to notice or communicate this failure, so it's
extremely difficult to use this functionality correctly, and in fact
almost all callers use `ZFS_SPACE_CHECK_NONE`.

This commit removes the `zfs_space_check_t` argument from
`dsl_sync_task_nowait()`, and always uses `ZFS_SPACE_CHECK_NONE`.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #10855
2020-09-04 10:29:39 -07:00
Toomas Soome
1144586b57
zio_ereport_post() and zio_ereport_start() return values are ignored
use (void) to silence analyzers.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Toomas Soome <tsoome@me.com>
Closes #10857
2020-08-31 19:35:11 -07:00
Ryan Moeller
a2f944a140
zpool: Change base URL for ZFS messages to openzfs-docs
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Kjeld Schouten <kjeld@schouten-lebbing.nl>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #10820
2020-08-26 21:43:06 -07:00
Ryan Moeller
6fe3498ca3
Import vdev ashift optimization from FreeBSD
Many modern devices use physical allocation units that are much
larger than the minimum logical allocation size accessible by
external commands. Two prevalent examples of this are 512e disk
drives (512b logical sector, 4K physical sector) and flash devices
(512b logical sector, 4K or larger allocation block size, and 128k
or larger erase block size). Operations that modify less than the
physical sector size result in a costly read-modify-write or garbage
collection sequence on these devices.

Simply exporting the true physical sector of the device to ZFS would
yield optimal performance, but has two serious drawbacks:

 1. Existing pools created with devices that have different logical
    and physical block sizes, but were configured to use the logical
    block size (e.g. because the OS version used for pool construction
    reported the logical block size instead of the physical block
    size) will suddenly find that the vdev allocation size has
    increased. This can be easily tolerated for active members of
    the array, but ZFS would prevent replacement of a vdev with
    another identical device because it now appears that the smaller
    allocation size required by the pool is not supported by the new
    device.

 2. The device's physical block size may be too large to be supported
    by ZFS. The optimal allocation size for the vdev may be quite
    large. For example, a RAID controller may export a vdev that
    requires read-modify-write cycles unless accessed using 64k
    aligned/sized requests. ZFS currently has an 8k minimum block
    size limit.

Reporting both the logical and physical allocation sizes for vdevs
solves these problems. A device may be used so long as the logical
block size is compatible with the configuration. By comparing the
logical and physical block sizes, new configurations can be optimized
and administrators can be notified of any existing pools that are
sub-optimal.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Matthew Macy <mmacy@freebsd.org>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #10619
2020-08-21 12:53:17 -07:00
Richard Laager
eaa25f1a8e
Remove GRUB restrictions
The GRUB restrictions are based around the pool's bootfs property.
Given the current situation where GRUB is not staying current with
OpenZFS pool features, having either a non-ZFS /boot or a separate
pool with limited features are pretty much the only long-term answers
for GRUB support.  Only the second case matters in this context.  For
the restrictions to be useful, the bootfs property would have to be set
on the boot pool, because that is where we need the restrictions, as
that is the pool that GRUB reads from. The documentation for bootfs
describes it as pointing to the root pool. That's also how it's used in
the initramfs. ZFS does not allow setting bootfs to point to a dataset
in another pool. (If it did, it'd be difficult-to-impossible to enforce
these restrictions cross-pool). Accordingly, bootfs is pretty much
useless for GRUB scenarios moving forward.

Even for users who have only one pool, the existing restrictions for
GRUB are incomplete. They don't prevent you from enabling the
unsupported checksums, for example. For that reason, I have ripped out
all the GRUB restrictions.

A little longer-term, I think extending the proposed features=portable
system to define a features=grub is a much more useful approach. The
user could set that on the boot pool at creation, and things would
Just Work.

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Laager <rlaager@wiktel.com>
Closes #8627
2020-08-17 23:12:39 -07:00
Matthew Ahrens
d87676a9fa
Fix i/o error handling of livelists and zap iteration
Pool-wide metadata is stored in the MOS (Meta Object Set).  This
metadata is stored in triplicate, in addition to any pool-level
reduncancy (e.g. RAIDZ).  However, if all 3+ copies of this metadata are
not available, we can still get EIO/ECKSUM when reading from the MOS.
If we encounter such an error in syncing context, we have typically
already committed to making a change that we now can't do because of the
corrupt/missing metadata.  We typically "handle" this with a `VERIFY()`
or `zfs_panic_recover()`.  This prevents the system from continuing on
in an undefined state, while minimizing the amount of error-handling
code.

However, there are some code paths that ignore these i/o errors, or
`ASSERT()` that they don't happen.  Since assertions are disabled on
non-debug builds, they effectively ignore them as well.  This can lead
to ZFS continuing on in an incorrect state, potentially leading to
on-disk inconsistencies.

This commit adds handling for these i/o errors on MOS metadata,
typically with a `VERIFY()`:

* Handle error return from `zap_cursor_retrieve()` in 4 places in
`dsl_deadlist.c`.

* Handle error return from `zap_contains()` in `dsl_dir_hold_obj()`.
Turns out this call isn't necessary because we can always call
`zap_lookup()`.

* Handle error return from `zap_lookup()` in `dsl_fs_ss_limit_check()`.

* Handle error return from `zap_remove()` in `dsl_dir_rename_sync()`.

* Handle error return from `zap_lookup()` in
`dsl_dir_remove_livelist()`.

* Handle error return from `dsl_process_sub_livelist()` in
`spa_livelist_delete_cb()`.

Additionally:

* Augment the internal history log message for `zfs destroy` to note
which method is used (e.g. bptree, livelist, or, synchronous) and the
mintxg.

* Correct a comment in `dbuf_init()`.

* Correct indentation in `dsl_dir_remove_livelist()`.

Reviewed by: Sara Hartse <sara.hartse@delphix.com>
Reviewed-by: George Wilson <george.wilson@delphix.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #10643
2020-08-05 10:22:09 -07:00
Serapheim Dimitropoulos
843e9ca2e1
Introduce names for ZTHRs
When debugging issues or generally analyzing the runtime of
a system it would be nice to be able to tell the different
ZTHRs running by name rather than having to analyze their
stack.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Co-authored-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Closes #10630
2020-07-29 09:43:33 -07:00
Alexander Motin
1743c737f5
Fix LOR between dp_config_rwlock and spa_props_lock
Our QE team during automated API testing hit deadlock in ZFS, caused
by lock order reversal.  From one side dsl_sync_task_sync() locks
dp_config_rwlock as writer and calls spa_sync_props(), which waits
for spa_props_lock.  From another spa_prop_get() locks spa_props_lock
and then calls dsl_pool_config_enter(), trying to lock dp_config_rwlock
as reader.

This patch makes spa_prop_get() lock dp_config_rwlock before
spa_props_lock, making the order consistent.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Closes #10553
2020-07-14 12:21:57 -07:00
Brian Behlendorf
9a49d3f3d3
Add device rebuild feature
The device_rebuild feature enables sequential reconstruction when
resilvering.  Mirror vdevs can be rebuilt in LBA order which may
more quickly restore redundancy depending on the pools average block
size, overall fragmentation and the performance characteristics
of the devices.  However, block checksums cannot be verified
as part of the rebuild thus a scrub is automatically started after
the sequential resilver completes.

The new '-s' option has been added to the `zpool attach` and
`zpool replace` command to request sequential reconstruction
instead of healing reconstruction when resilvering.

    zpool attach -s <pool> <existing vdev> <new vdev>
    zpool replace -s <pool> <old vdev> <new vdev>

The `zpool status` output has been updated to report the progress
of sequential resilvering in the same way as healing resilvering.
The one notable difference is that multiple sequential resilvers
may be in progress as long as they're operating on different
top-level vdevs.

The `zpool wait -t resilver` command was extended to wait on
sequential resilvers.  From this perspective they are no different
than healing resilvers.

Sequential resilvers cannot be supported for RAIDZ, but are
compatible with the dRAID feature being developed.

As part of this change the resilver_restart_* tests were moved
in to the functional/replacement directory.  Additionally, the
replacement tests were renamed and extended to verify both
resilvering and rebuilding.

Original-patch-by: Isaac Huang <he.huang@intel.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: John Poduska <jpoduska@datto.com>
Co-authored-by: Mark Maybee <mmaybee@cray.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #10349
2020-07-03 11:05:50 -07:00
Arvind Sankar
65c7cc49bf Mark functions as static
Mark functions used only in the same translation unit as static. This
only includes functions that do not have a prototype in a header file
either.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Closes #10470
2020-06-18 12:20:38 -07:00
George Amanakis
b7654bd794
Trim L2ARC
The l2arc_evict() function is responsible for evicting buffers which
reference the next bytes of the L2ARC device to be overwritten. Teach
this function to additionally TRIM that vdev space before it is
overwritten if the device has been filled with data. This is done by
vdev_trim_simple() which trims by issuing a new type of TRIM,
TRIM_TYPE_SIMPLE.

We also implement a "Trim Ahead" feature. It is a zfs module parameter,
expressed in % of the current write size. This trims ahead of the
current write size. A minimum of 64MB will be trimmed. The default is 0
which disables TRIM on L2ARC as it can put significant stress to
underlying storage devices. To enable TRIM on L2ARC we set
l2arc_trim_ahead > 0.

We also implement TRIM of the whole cache device upon addition to a
pool, pool creation or when the header of the device is invalid upon
importing a pool or onlining a cache device. This is dependent on
l2arc_trim_ahead > 0. TRIM of the whole device is done with
TRIM_TYPE_MANUAL so that its status can be monitored by zpool status -t.
We save the TRIM state for the whole device and the time of completion
on-disk in the header, and restore these upon L2ARC rebuild so that
zpool status -t can correctly report them. Whole device TRIM is done
asynchronously so that the user can export of the pool or remove the
cache device while it is trimming (ie if it is too slow).

We do not TRIM the whole device if persistent L2ARC has been disabled by
l2arc_rebuild_enabled = 0 because we may not want to lose all cached
buffers (eg we may want to import the pool with
l2arc_rebuild_enabled = 0 only once because of memory pressure). If
persistent L2ARC has been disabled by setting the module parameter
l2arc_rebuild_blocks_min_l2size to a value greater than the size of the
cache device then the whole device is trimmed upon creation or import of
a pool if l2arc_trim_ahead > 0.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Adam D. Moss <c@yotes.com>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #9713
Closes #9789 
Closes #10224
2020-06-09 10:15:08 -07:00
Jorgen Lundman
c9e319faae
Replace sprintf()->snprintf() and strcpy()->strlcpy()
The strcpy() and sprintf() functions are deprecated on some platforms.
Care is needed to ensure correct size is used.  If some platforms
miss snprintf, we can add a #define to sprintf, likewise strlcpy().

The biggest change is adding a size parameter to zfs_id_to_fuidstr().

The various *_impl_get() functions are only used on linux and have
not yet been updated.

Reviewed by: Sean Eric Fagan <sef@ixsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Jorgen Lundman <lundman@lundman.net>
Closes #10400
2020-06-07 11:42:12 -07:00
George Amanakis
1b664952ae
Enable splitting mirrors with indirect vdevs
When a top-level vdev is removed from a pool it is converted to an
indirect vdev. Until now splitting such mirrored pools was not possible
with zpool split. This patch enables handling of indirect vdevs and
splitting of those pools with zpool split.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #10283
2020-05-06 10:32:28 -07:00
Matthew Ahrens
32d805c3e2
Use a struct to organize metaslab-group-allocator fields
Each metaslab group (of which there is one per top-level vdev) has
several (4, by default) "metaslab group allocators".  Each "allocator"
has its own metaslab that it prefers to allocate from (the "primary"
allocator), and each can perform allocations concurrently with the other
allocators.  In addition to the primary metaslab, there are several
other fields that need to be tracked separately for each allocator.
These are currently stored as several arrays in the metaslab_group_t,
each array indexed by allocator number.

This change organizes all the metaslab-group-allocator-specific fields
into a new struct, metaslab_group_allocator_t.  The metaslab_group_t now
needs only one array indexed by the allocator number - which contains
the metaslab_group_allocator_t's.

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #10213
2020-04-22 10:26:56 -07:00
George Amanakis
77f6826b83
Persistent L2ARC
This commit makes the L2ARC persistent across reboots. We implement
a light-weight persistent L2ARC metadata structure that allows L2ARC
contents to be recovered after a reboot. This significantly eases the
impact a reboot has on read performance on systems with large caches.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Saso Kiselkov <skiselkov@gmail.com>
Co-authored-by: Jorgen Lundman <lundman@lundman.net>
Co-authored-by: George Amanakis <gamanakis@gmail.com>
Ported-by: Yuxuan Shui <yshuiv7@gmail.com>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #925 
Closes #1823 
Closes #2672 
Closes #3744 
Closes #9582
2020-04-10 10:33:35 -07:00
Matthew Macy
8b27e08ed8
Add separate field for indicating that spa is in middle of split
By default it's not possible to open a device already owned by an
active vdev. It's necessary to make an exception to this for vdev
split. The FreeBSD platform code will make an exception if
spa_is splitting is set to to true.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #10178
2020-04-09 09:59:31 -07:00
Brian Behlendorf
2288d41968
Add trim support to zpool wait
Manual trims fall into the category of long-running pool activities
which people might want to wait synchronously for. This change adds
support to 'zpool wait' for waiting for manual trim operations to
complete. It also adds a '-w' flag to 'zpool trim' which can be used to
turn 'zpool trim' into a synchronous operation.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Signed-off-by: John Gallagher <john.gallagher@delphix.com>
Closes #10071
2020-03-04 15:07:11 -08:00
Matthew Ahrens
9cdf7b1f6b
Improve zfs destroy performance with zio_t-free zio_free()
When "zfs destroy" is run, it completes quickly, and in the background
we locate the blocks to free and free them.  This background activity
can be observed with `zpool get freeing` and `zpool wait -t free ...`.

This background activity is processed by a single thread (the spa_sync
thread) which calls zio_free() on each of the blocks to free.  With even
modest storage performance, the CPU consumption of zio_free() can be the
performance bottleneck.

Performance of zio_free() can be improved by not actually creating a
zio_t in the common case (non-dedup, non-gang), instead calling
metaslab_free() directly.  This avoids the CPU cost of allocating the
zio_t, and more importantly the cost of adding and later removing this
zio_t from the parent zio's child list.

The result is that performance of background freeing more than doubles,
from 0.6 million blocks per second to 1.3 million blocks per second.

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <gwilson@delphix.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #10034
2020-02-28 14:49:44 -08:00
Matthew Ahrens
ec21397127
async zvol minor node creation interferes with receive
When we finish a zfs receive, dmu_recv_end_sync() calls
zvol_create_minors(async=TRUE).  This kicks off some other threads that
create the minor device nodes (in /dev/zvol/poolname/...).  These async
threads call zvol_prefetch_minors_impl() and zvol_create_minor(), which
both call dmu_objset_own(), which puts a "long hold" on the dataset.
Since the zvol minor node creation is asynchronous, this can happen
after the `ZFS_IOC_RECV[_NEW]` ioctl and `zfs receive` process have
completed.

After the first receive ioctl has completed, userland may attempt to do
another receive into the same dataset (e.g. the next incremental
stream).  This second receive and the asynchronous minor node creation
can interfere with one another in several different ways, because they
both require exclusive access to the dataset:

1. When the second receive is finishing up, dmu_recv_end_check() does
dsl_dataset_handoff_check(), which can fail with EBUSY if the async
minor node creation already has a "long hold" on this dataset.  This
causes the 2nd receive to fail.

2. The async udev rule can fail if zvol_id and/or systemd-udevd try to
open the device while the the second receive's async attempt at minor
node creation owns the dataset (via zvol_prefetch_minors_impl).  This
causes the minor node (/dev/zd*) to exist, but the udev-generated
/dev/zvol/... to not exist.

3. The async minor node creation can silently fail with EBUSY if the
first receive's zvol_create_minor() trys to own the dataset while the
second receive's zvol_prefetch_minors_impl already owns the dataset.

To address these problems, this change synchronously creates the minor
node.  To avoid the lock ordering problems that the asynchrony was
introduced to fix (see #3681), we create the minor nodes from open
context, with no locks held, rather than from syncing contex as was
originally done.

Implementation notes:

We generally do not need to traverse children or prefetch anything (e.g.
when running the recv, snapshot, create, or clone subcommands of zfs).
We only need recursion when importing/opening a pool and when loading
encryption keys.  The existing recursive, asynchronous, prefetching code
is preserved for use in these cases.

Channel programs may need to create zvol minor nodes, when creating a
snapshot of a zvol with the snapdev property set.  We figure out what
snapshots are created when running the LUA program in syncing context.
In this case we need to remember what snapshots were created, and then
try to create their minor nodes from open context, after the LUA code
has completed.

There are additional zvol use cases that asynchronously own the dataset,
which can cause similar problems.  E.g. changing the volmode or snapdev
properties.  These are less problematic because they are not recursive
and don't touch datasets that are not involved in the operation, there
is still potential for interference with subsequent operations.  In the
future, these cases should be similarly converted to create the zvol
minor node synchronously from open context.

The async tasks of removing and renaming minors do not own the objset,
so they do not have this problem.  However, it may make sense to also
convert these operations to happen synchronously from open context, in
the future.

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Prakash Surya <prakash.surya@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
External-issue: DLPX-65948
Closes #7863
Closes #9885
2020-02-03 09:33:14 -08:00
loli10K
c24fa4b19a Fix "zpool add -n" for dedup, special and log devices
For dedup, special and log devices "zpool add -n" does not print
correctly their vdev type:

~# zpool add -n pool dedup /tmp/dedup special /tmp/special log /tmp/log
would update 'pool' to the following configuration:
	pool
	  /tmp/normal
	  /tmp/dedup
	  /tmp/special
	  /tmp/log

This could lead storage administrators to modify their ZFS pools to
unexpected and unintended vdev configurations.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #9783 
Closes #9390
2020-01-06 15:40:06 -08:00
Matthew Macy
2a8ba608d3 Replace ASSERTV macro with compiler annotation
Remove the ASSERTV macro and handle suppressing unused 
compiler warnings for variables only in ASSERTs using the 
__attribute__((unused)) compiler annotation.  The annotation
is understood by both gcc and clang.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #9671
2019-12-05 12:37:00 -08:00
jwpoduska
3c819a2c7d Prevent unnecessary resilver restarts
If a device is participating in an active resilver, then it will have a
non-empty DTL. Operations like vdev_{open,reopen,probe}() can cause the
resilver to be restarted (or deferred to be restarted later), which is
unnecessary if the DTL is still covered by the current scan range. This
is similar to the logic in vdev_dtl_should_excise() where the DTL can
only be excised if it's max txg is in the resilvered range.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Gallagher <john.gallagher@delphix.com>
Reviewed-by: Kjeld Schouten <kjeld@schouten-lebbing.nl>
Signed-off-by: John Poduska <jpoduska@datto.com>
Issue #840 
Closes #9155
Closes #9378
Closes #9551
Closes #9588
2019-11-27 10:15:01 -08:00
Matthew Macy
da92d5cbb3 Add zfs_file_* interface, remove vnodes
Provide a common zfs_file_* interface which can be implemented on all 
platforms to perform normal file access from either the kernel module
or the libzpool library.

This allows all non-portable vnode_t usage in the common code to be 
replaced by the new portable zfs_file_t.  The associated vnode and
kobj compatibility functions, types, and macros have been removed
from the SPL.  Moving forward, vnodes should only be used in platform
specific code when provided by the native operating system.

Reviewed-by: Sean Eric Fagan <sef@ixsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #9556
2019-11-21 09:32:57 -08:00
Matthew Macy
4a22ba5be0 Minor spa portability fixes
- FreeBSD's rootpool import code uses spa_config_parse
- Move the zvol_create_minors call out from under the
  spa_namespace_lock in spa_import. It isn't needed and it causes
  a lock order reversal on FreeBSD.

Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #9499
2019-10-28 09:51:53 -07:00
loli10K
715c996d3b Fix pool creation with feature@allocation_classes disabled
When "feature@allocation_classes" is not enabled on the pool no vdev
with "special" or "dedup" allocation type should be allowed to exist in
the vdev tree.

Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #9427 
Closes #9429
2019-10-10 16:39:41 -07:00
Paul Dagnelie
ca5777793e Reduce loaded range tree memory usage
This patch implements a new tree structure for ZFS, and uses it to 
store range trees more efficiently.

The new structure is approximately a B-tree, though there are some 
small differences from the usual characterizations. The tree has core 
nodes and leaf nodes; each contain data elements, which the elements 
in the core nodes acting as separators between its children. The 
difference between core and leaf nodes is that the core nodes have an 
array of children, while leaf nodes don't. Every node in the tree may 
be only partially full; in most cases, they are all at least 50% full 
(in terms of element count) except for the root node, which can be 
less full. Underfull nodes will steal from their neighbors or merge to 
remain full enough, while overfull nodes will split in two. The data 
elements are contained in tree-controlled buffers; they are copied 
into these on insertion, and overwritten on deletion. This means that 
the elements are not independently allocated, which reduces overhead, 
but also means they can't be shared between trees (and also that 
pointers to them are only valid until a side-effectful tree operation 
occurs). The overhead varies based on how dense the tree is, but is 
usually on the order of about 50% of the element size; the per-node 
overheads are very small, and so don't make a significant difference. 
The trees can accept arbitrary records; they accept a size and a 
comparator to allow them to be used for a variety of purposes.

The new trees replace the AVL trees used in the range trees today. 
Currently, the range_seg_t structure contains three 8 byte integers 
of payload and two 24 byte avl_tree_node_ts to handle its storage in 
both an offset-sorted tree and a size-sorted tree (total size: 64 
bytes). In the new model, the range seg structures are usually two 4 
byte integers, but a separate one needs to exist for the size-sorted 
and offset-sorted tree. Between the raw size, the 50% overhead, and 
the double storage, the new btrees are expected to use 8*1.5*2 = 24 
bytes per record, or 33.3% as much memory as the AVL trees (this is 
for the purposes of storing metaslab range trees; for other purposes, 
like scrubs, they use ~50% as much memory).

We reduced the size of the payload in the range segments by teaching 
range trees about starting offsets and shifts; since metaslabs have a 
fixed starting offset, and they all operate in terms of disk sectors, 
we can store the ranges using 4-byte integers as long as the size of 
the metaslab divided by the sector size is less than 2^32. For 512-byte
sectors, this is a 2^41 (or 2TB) metaslab, which with the default
settings corresponds to a 256PB disk. 4k sector disks can handle 
metaslabs up to 2^46 bytes, or 2^63 byte disks. Since we do not 
anticipate disks of this size in the near future, there should be 
almost no cases where metaslabs need 64-byte integers to store their 
ranges. We do still have the capability to store 64-byte integer ranges 
to account for cases where we are storing per-vdev (or per-dnode) trees, 
which could reasonably go above the limits discussed. We also do not 
store fill information in the compact version of the node, since it 
is only used for sorted scrub.

We also optimized the metaslab loading process in various other ways
to offset some inefficiencies in the btree model. While individual
operations (find, insert, remove_from) are faster for the btree than 
they are for the avl tree, remove usually requires a find operation, 
while in the AVL tree model the element itself suffices. Some clever 
changes actually caused an overall speedup in metaslab loading; we use 
approximately 40% less cpu to load metaslabs in our tests on Illumos.

Another memory and performance optimization was achieved by changing 
what is stored in the size-sorted trees. When a disk is heavily 
fragmented, the df algorithm used by default in ZFS will almost always 
find a number of small regions in its initial cursor-based search; it 
will usually only fall back to the size-sorted tree to find larger 
regions. If we increase the size of the cursor-based search slightly, 
and don't store segments that are smaller than a tunable size floor 
in the size-sorted tree, we can further cut memory usage down to 
below 20% of what the AVL trees store. This also results in further 
reductions in CPU time spent loading metaslabs.

The 16KiB size floor was chosen because it results in substantial memory 
usage reduction while not usually resulting in situations where we can't 
find an appropriate chunk with the cursor and are forced to use an 
oversized chunk from the size-sorted tree. In addition, even if we do 
have to use an oversized chunk from the size-sorted tree, the chunk 
would be too small to use for ZIL allocations, so it isn't as big of a 
loss as it might otherwise be. And often, more small allocations will 
follow the initial one, and the cursor search will now find the 
remainder of the chunk we didn't use all of and use it for subsequent 
allocations. Practical testing has shown little or no change in 
fragmentation as a result of this change.

If the size-sorted tree becomes empty while the offset sorted one still 
has entries, it will load all the entries from the offset sorted tree 
and disregard the size floor until it is unloaded again. This operation 
occurs rarely with the default setting, only on incredibly thoroughly 
fragmented pools.

There are some other small changes to zdb to teach it to handle btrees, 
but nothing major.
                                           
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed by: Sebastien Roy seb@delphix.com
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes #9181
2019-10-09 10:36:03 -07:00
loli10K
b24771a8c9 Prevent gcc -Werror=maybe-uninitialized warnings in spa_wait_common()
This commit fixes the following build failure detected on Debian9
(GCC 6.3.0):

     CC [M]  module/zfs/spa.o
   module/zfs/spa.c: In function ‘spa_wait_common.part.31’:
   module/zfs/spa.c:9468:6: error: ‘in_progress’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
      if (!in_progress || spa->spa_waiters_cancel || error)
         ^
   cc1: all warnings being treated as errors

Reviewed-by: Chris Dunlop <chris@onthe.net.au>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Gallagher <john.gallagher@delphix.com>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #9326
2019-09-16 10:46:02 -07:00