c/mirror_zfs
1
0
Fork 0
mirror of https://git.proxmox.com/git/mirror_zfs.git synced 2026-05-22 18:40:43 +03:00
Code Issues Packages Projects Releases Wiki Activity

Illumos #3581 spa_zio_taskq[ZIO_TYPE_FREE][ZIO_TASKQ_ISSUE]->tq_lock contention

Browse Source 
3581 spa_zio_taskq[ZIO_TYPE_FREE][ZIO_TASKQ_ISSUE]->tq_lock is piping hot

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Gordon Ross <gordon.ross@nexenta.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  illumos/illumos-gate@ec94d32
  https://illumos.org/issues/3581

Notes for Linux port:

Earlier commit 08d08eb reduced contention on this taskq lock by simply
reducing the number of z_fr_iss threads from 100 to one-per-CPU.  We
also optimized the taskq implementation in zfsonlinux/spl@3c6ed54.
These changes significantly improved unlink performance to acceptable
levels.

This patch further reduces time spent spinning on this lock by
randomly dispatching the work items over multiple independent task
queues.  The Illumos ZFS developers stated that this lock contention
only arose after "3329 spa_sync() spends 10-20% of its time in
spa_free_sync_cb()" was landed.  It's not clear if 3329 affects the
Linux port or not.  I didn't see spa_free_sync_cb() show up in
oprofile sessions while unlinking large files, but I may just not
have used the right test case.

I tested unlinking a 1 TB of data with and without the patch and
didn't observe a meaningful difference in elapsed time.  However,
oprofile showed that the percent time spent in taskq_thread() was
reduced from about 16% to about 5%.  Aside from a possible slight
performance benefit this may be worth landing if only for the sake of
maintaining consistency with upstream.

Ported-by: Ned Bass <bass6@llnl.gov>
Closes #1327
This commit is contained in:
Adam Leventhal
2013-05-06 12:24:30 -07:00
committed by Brian Behlendorf
parent 55d85d5a8c
commit 7ef5e54e2e
4 changed files with 174 additions and 83 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/sys/spa_impl.h
+12 -4
View File
@@ -80,16 +80,16 @@ typedef struct spa_config_dirent {
char *scd_path;
} spa_config_dirent_t;
enum zio_taskq_type {
typedef enum zio_taskq_type {
ZIO_TASKQ_ISSUE = 0,
ZIO_TASKQ_ISSUE_HIGH,
ZIO_TASKQ_INTERRUPT,
ZIO_TASKQ_INTERRUPT_HIGH,
ZIO_TASKQ_TYPES
};
} zio_taskq_type_t;
/*
* State machine for the zpool-pooname process. The states transitions
* State machine for the zpool-poolname process. The states transitions
* are done as follows:
*
* From To Routine
@@ -107,6 +107,11 @@ typedef enum spa_proc_state {
SPA_PROC_GONE /* spa_thread() is exiting, spa_proc = &p0 */
} spa_proc_state_t;
typedef struct spa_taskqs {
uint_t stqs_count;
taskq_t **stqs_taskq;
} spa_taskqs_t;
struct spa {
/*
* Fields protected by spa_namespace_lock.
@@ -125,7 +130,7 @@ struct spa {
uint8_t spa_sync_on; /* sync threads are running */
spa_load_state_t spa_load_state; /* current load operation */
uint64_t spa_import_flags; /* import specific flags */
taskq_t *spa_zio_taskq[ZIO_TYPES][ZIO_TASKQ_TYPES];
spa_taskqs_t spa_zio_taskq[ZIO_TYPES][ZIO_TASKQ_TYPES];
dsl_pool_t *spa_dsl_pool;
boolean_t spa_is_initializing; /* true while opening pool */
metaslab_class_t *spa_normal_class; /* normal data class */
@@ -243,6 +248,9 @@ struct spa {
extern char *spa_config_path;
extern void spa_taskq_dispatch_ent(spa_t *spa, zio_type_t t, zio_taskq_type_t q,
task_func_t *func, void *arg, uint_t flags, taskq_ent_t *ent);
#ifdef __cplusplus
}
#endif