Etienne Dechamps 34037afe24 Improve ZVOL queue behavior. ... The Linux block device queue subsystem exposes a number of configurable settings described in Linux block/blk-settings.c. The defaults for these settings are tuned for hard drives, and are not optimized for ZVOLs. Proper configuration of these options would allow upper layers (I/O scheduler) to take better decisions about write merging and ordering. Detailed rationale: - max_hw_sectors is set to unlimited (UINT_MAX). zvol_write() is able to handle writes of any size, so there's no reason to impose a limit. Let the upper layer decide. - max_segments and max_segment_size are set to unlimited. zvol_write() will copy the requests' contents into a dbuf anyway, so the number and size of the segments are irrelevant. Let the upper layer decide. - physical_block_size and io_opt are set to the ZVOL's block size. This has the potential to somewhat alleviate issue #361 for ZVOLs, by warning the upper layers that writes smaller than the volume's block size will be slow. - The NONROT flag is set to indicate this isn't a rotational device. Although the backing zpool might be composed of rotational devices, the resulting ZVOL often doesn't exhibit the same behavior due to the COW mechanisms used by ZFS. Setting this flag will prevent upper layers from making useless decisions (such as reordering writes) based on incorrect assumptions about the behavior of the ZVOL. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>		2012-02-07 16:23:06 -08:00
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fm	Improve ZVOL queue behavior.	2012-02-07 16:23:06 -08:00
fs	Improve ZVOL queue behavior.	2012-02-07 16:23:06 -08:00
arc.h	Linux 3.1 compat, super_block->s_shrink	2012-01-11 11:46:02 -08:00
avl_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
avl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
bplist.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
bpobj.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dbuf.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
ddt.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dmu_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dmu_objset.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dmu_traverse.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dmu_tx.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dmu_zfetch.h	Add missing ZFS tunables	2011-05-04 10:02:37 -07:00
dmu.h	Illumos #755: dmu_recv_stream builds incomplete guid_to_ds_map	2011-10-18 11:18:14 -07:00
dnode.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dsl_dataset.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dsl_deadlist.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dsl_deleg.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dsl_dir.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dsl_pool.h	Prototype/structure update for Linux	2011-02-10 09:27:21 -08:00
dsl_prop.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dsl_scan.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dsl_synctask.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
efi_partition.h	Make libefi-created GPT compatible with gptfdisk	2011-09-26 09:44:43 -07:00
Makefile.am	Add the release component to headers	2012-01-18 12:19:47 -08:00
Makefile.in	Improve ZVOL queue behavior.	2012-02-07 16:23:06 -08:00
metaslab_impl.h	Illumos #1051: zfs should handle imbalanced luns	2011-08-01 12:09:11 -07:00
metaslab.h	Illumos #1051: zfs should handle imbalanced luns	2011-08-01 12:09:11 -07:00
nvpair_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
nvpair.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
refcount.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
rrwlock.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
sa_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
sa.h	Implement SA based xattrs	2011-11-28 15:45:51 -08:00
spa_boot.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
spa_impl.h	Illumos #1051: zfs should handle imbalanced luns	2011-08-01 12:09:11 -07:00
spa.h	Illumos #1051: zfs should handle imbalanced luns	2011-08-01 12:09:11 -07:00
space_map.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
txg_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
txg.h	Add API to wait for pending commit callbacks	2011-02-16 11:20:06 -08:00
u8_textprep_data.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
u8_textprep.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
uberblock_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
uberblock.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
uio_impl.h	Add basic uio support	2011-02-10 09:21:43 -08:00
unique.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
uuid.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
vdev_disk.h	Linux 2.6.x compat, blkdev_compat.h	2011-02-23 12:29:38 -08:00
vdev_file.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
vdev_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
vdev.h	Add missing ZFS tunables	2011-05-04 10:02:37 -07:00
xvattr.h	Add xvattr support	2011-03-02 11:43:50 -08:00
zap_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zap_leaf.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zap.h	Export symbols for the full ZAP API	2011-09-27 16:12:36 -07:00
zfs_acl.h	Add xvattr support	2011-03-02 11:43:50 -08:00
zfs_context.h	Cleanup ZFS debug infrastructure	2012-02-02 11:24:30 -08:00
zfs_debug.h	Cleanup ZFS debug infrastructure	2012-02-02 11:24:30 -08:00
zfs_dir.h	Prototype/structure update for Linux	2011-02-10 09:27:21 -08:00
zfs_fuid.h	Prototype/structure update for Linux	2011-02-10 09:27:21 -08:00
zfs_ioctl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zfs_onexit.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zfs_rlock.h	Range lock performance improvements	2011-03-08 12:44:06 -08:00
zfs_sa.h	Implement SA based xattrs	2011-11-28 15:45:51 -08:00
zfs_stat.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zfs_vfsops.h	Increase link count limit to 2^31-1	2012-01-13 11:43:59 -08:00
zfs_vnops.h	Cleanup mmap(2) writes	2011-08-02 10:34:55 -07:00
zfs_znode.h	Implement SA based xattrs	2011-11-28 15:45:51 -08:00
zil_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zil.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zio_checksum.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zio_compress.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zio_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zio.h	Illumos #734: Use taskq_dispatch_ent() interface	2011-12-14 09:19:30 -08:00
zpl.h	Linux 3.1 compat, super_block->s_shrink	2012-01-11 11:46:02 -08:00
zrlock.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zvol.h	Linux 2.6.x compat, blkdev_compat.h	2011-02-23 12:29:38 -08:00