Brian Behlendorf 86dd0fd922 Pre-allocate vdev I/O buffers ... The vdev queue layer may require a small number of buffers when attempting to create aggregate I/O requests. Rather than attempting to allocate them from the global zio buffers, which is slow under memory pressure, it makes sense to pre-allocate them because... 1) These buffers are short lived. They are only required for the life of a single I/O at which point they can be used by the next I/O. 2) The maximum number of concurrent buffers needed by a vdev is small. It's roughly limited by the zfs_vdev_max_pending tunable which defaults to 10. By keeping a small list of these buffer per-vdev we can ensure one is always available when we need it. This significantly reduces contention on the vq->vq_lock, because we no longer need to perform a slow allocation under this lock. This is particularly important when memory is already low on the system. It would probably be wise to extend the use of these buffers beyond aggregate I/O and in to the raidz implementation. The inability to quickly allocate buffer for the parity stripes could result in similiar problems. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>		2012-08-27 12:01:37 -07:00
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fm	Remove autotools products	2012-08-27 11:47:44 -07:00
fs	Remove autotools products	2012-08-27 11:47:44 -07:00
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	Export dbuf_* symbols	2012-08-10 16:45:13 -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	Add --enable-debug-dmu-tx configure option	2012-03-23 12:25:17 -07:00
dmu_zfetch.h	Add missing ZFS tunables	2011-05-04 10:02:37 -07:00
dmu.h	Illumos #1644, #1645, #1646, #1647, #1708	2012-07-31 09:25:30 -07:00
dnode.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dsl_dataset.h	Illumos #1644, #1645, #1646, #1647, #1708	2012-07-31 09:25:30 -07:00
dsl_deadlist.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
dsl_deleg.h	Illumos #1644, #1645, #1646, #1647, #1708	2012-07-31 09:25:30 -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	Move partition scanning from userspace to module.	2012-07-17 09:17:31 -07:00
Makefile.am	Add .zfs control directory	2012-03-22 13:03:47 -07:00
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	Add sa_spill_rele() interface	2012-03-07 16:28:00 -08:00
spa_boot.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
spa_impl.h	Illumos #1693: persistent 'comment' field for a zpool	2012-08-08 11:49:37 -07:00
spa.h	Illumos #1748: desire support for reguid in zfs	2012-07-11 13:08:56 -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	Pre-allocate vdev I/O buffers	2012-08-27 12:01:37 -07:00
vdev.h	Illumos #1949, #1953	2012-07-11 13:33:31 -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	Fix build failures on PaX/GRSecurity patched kernels	2012-07-17 09:22:43 -07:00
zfs_context.h	Revert Disable direct reclaim for z_wr_* threads	2012-08-27 12:01:37 -07:00
zfs_ctldir.h	Use ULL suffix in constants	2012-07-10 11:31:55 -07:00
zfs_debug.h	Cleanly support debug packages	2012-02-27 14:08:17 -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	Speed up 'zfs list -t snapshot -o name -s name'	2012-06-14 09:49:04 -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	Add .zfs control directory	2012-03-22 13:03:47 -07:00
zfs_vnops.h	Cleanup mmap(2) writes	2011-08-02 10:34:55 -07:00
zfs_znode.h	Add .zfs control directory	2012-03-22 13:03:47 -07:00
zil_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zil.h	Add ZIL statistics.	2012-06-29 09:56:51 -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	Pre-allocate vdev I/O buffers	2012-08-27 12:01:37 -07:00
zpl.h	Linux 3.3 compat, iops->create()/mkdir()/mknod()	2012-04-30 12:52:38 -07:00
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