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34037afe24
freebsd-dev/module/zfs
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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
..
arc.c Cleanup ZFS debug infrastructure 2012-02-02 11:24:30 -08:00
bplist.c Fix gcc missing parenthesis warnings 2010-08-31 08:38:35 -07:00
bpobj.c Update to onnv_147 2010-08-26 14:24:34 -07:00
dbuf.c Illumos #764: panic in zfs:dbuf_sync_list 2011-08-01 12:09:11 -07:00
ddt_zap.c Fix stack ddt_zap_lookup() 2011-05-31 12:17:27 -07:00
ddt.c Fix stack ddt_class_contains() 2011-05-31 12:17:27 -07:00
dmu_diff.c Update to onnv_147 2010-08-26 14:24:34 -07:00
dmu_object.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
dmu_objset.c Merge branch 'zpl' 2011-02-18 09:31:25 -08:00
dmu_send.c Illumos #755: dmu_recv_stream builds incomplete guid_to_ds_map 2011-10-18 11:18:14 -07:00
dmu_traverse.c Revert "Fix stack traverse_visitbp()" 2011-05-31 12:17:27 -07:00
dmu_tx.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
dmu_zfetch.c Add missing ZFS tunables 2011-05-04 10:02:37 -07:00
dmu.c Suppress large kmem_alloc() warning 2011-02-10 09:27:22 -08:00
dnode_sync.c Fix dbuf eviction assertion 2010-08-31 08:38:45 -07:00
dnode.c Improve meta data performance 2011-11-03 10:19:21 -07:00
dsl_dataset.c Illumos #1092: zfs refratio property 2011-08-01 12:09:11 -07:00
dsl_deadlist.c Update core ZFS code from build 121 to build 141. 2010-05-28 13:45:14 -07:00
dsl_deleg.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
dsl_dir.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
dsl_pool.c Add missing ZFS tunables 2011-05-04 10:02:37 -07:00
dsl_prop.c Fix enum compiler warning 2011-02-23 12:52:51 -08:00
dsl_scan.c Add missing ZFS tunables 2011-05-04 10:02:37 -07:00
dsl_synctask.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
fm.c Add missing ZFS tunables 2011-05-04 10:02:37 -07:00
gzip.c Fix zmod.h usage in userspace 2010-08-31 08:38:46 -07:00
lzjb.c Fix stack lzjb 2010-08-31 08:38:49 -07:00
Makefile.in Implemented NFS export_operations. 2011-04-29 12:36:13 -07:00
metaslab.c Illumos #1051: zfs should handle imbalanced luns 2011-08-01 12:09:11 -07:00
refcount.c Fix gcc uninitialized variable warnings 2010-08-31 08:38:43 -07:00
rrwlock.c Enable rrwlock.c compilation 2010-12-07 16:05:25 -08:00
sa.c Implement SA based xattrs 2011-11-28 15:45:51 -08:00
sha256.c Add linux sha2 support 2010-08-31 13:41:59 -07:00
spa_boot.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
spa_config.c Prototype/structure update for Linux 2011-02-10 09:27:21 -08:00
spa_errlog.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
spa_history.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
spa_misc.c Cleanup ZFS debug infrastructure 2012-02-02 11:24:30 -08:00
spa.c Reduce number of zio free threads 2012-01-17 08:54:00 -08:00
space_map.c Update core ZFS code from build 121 to build 141. 2010-05-28 13:45:14 -07:00
txg.c Illumos #1313: Integer overflow in txg_delay() 2011-08-01 12:09:43 -07:00
uberblock.c Update core ZFS code from build 121 to build 141. 2010-05-28 13:45:14 -07:00
unique.c Fix gcc ident pragma warnings 2010-08-27 15:34:02 -07:00
vdev_cache.c Illumos #175: zfs vdev cache consumes excessive memory 2011-08-01 12:09:11 -07:00
vdev_disk.c Linux 2.6.37 compat, WRITE_FLUSH_FUA 2011-06-17 14:37:26 -07:00
vdev_file.c Prototype/structure update for Linux 2011-02-10 09:27:21 -08:00
vdev_label.c Fix gcc uninitialized variable warnings 2010-08-31 08:38:43 -07:00
vdev_mirror.c Fix gcc c90 compliance warnings 2010-08-27 15:28:32 -07:00
vdev_missing.c Update core ZFS code from build 121 to build 141. 2010-05-28 13:45:14 -07:00
vdev_queue.c Add missing ZFS tunables 2011-05-04 10:02:37 -07:00
vdev_raidz.c Fix variables named current 2010-08-31 08:38:44 -07:00
vdev_root.c Fix gcc c90 compliance warnings 2010-08-27 15:28:32 -07:00
vdev.c Allow setting bootfs on any pool 2012-01-17 13:49:07 -08:00
zap_leaf.c Fix gcc uninitialized variable warnings 2010-08-31 08:38:43 -07:00
zap_micro.c Export symbols for the full ZAP API 2011-09-27 16:12:36 -07:00
zap.c Fix rw_init() usage 2010-08-31 08:38:46 -07:00
zfs_acl.c Linux compat 2.6.39: mount_nodev() 2011-07-01 13:36:39 -07:00
zfs_byteswap.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
zfs_debug.c Cleanup ZFS debug infrastructure 2012-02-02 11:24:30 -08:00
zfs_dir.c Allow multiple values per directory entry 2012-02-02 11:22:08 -08:00
zfs_fm.c Initial zio delay timing 2010-10-12 14:55:02 -07:00
zfs_fuid.c Drop HAVE_XVATTR macros 2011-03-02 11:44:34 -08:00
zfs_ioctl.c Cleanup ZFS debug infrastructure 2012-02-02 11:24:30 -08:00
zfs_log.c Drop HAVE_XVATTR macros 2011-03-02 11:44:34 -08:00
zfs_onexit.c Add linux kernel device support 2010-08-31 13:41:50 -07:00
zfs_replay.c Use Linux ATTR_ versions 2011-03-03 11:29:15 -08:00
zfs_rlock.c Range lock performance improvements 2011-03-08 12:44:06 -08:00
zfs_sa.c Export symbol zfs_attr_table 2012-01-27 09:23:36 -08:00
zfs_vfsops.c Linux 3.1 compat, super_block->s_shrink 2012-01-11 11:46:02 -08:00
zfs_vnops.c Allow multiple values per directory entry 2012-02-02 11:22:08 -08:00
zfs_znode.c Linux 3.1 compat, super_block->s_shrink 2012-01-11 11:46:02 -08:00
zil.c Illumos #883: ZIL reuse during remount corruption 2011-08-01 12:09:11 -07:00
zio_checksum.c Update core ZFS code from build 121 to build 141. 2010-05-28 13:45:14 -07:00
zio_compress.c Update core ZFS code from build 121 to build 141. 2010-05-28 13:45:14 -07:00
zio_inject.c Add missing ZFS tunables 2011-05-04 10:02:37 -07:00
zio.c Illumos #734: Use taskq_dispatch_ent() interface 2011-12-14 09:19:30 -08:00
zle.c Update core ZFS code from build 121 to build 141. 2010-05-28 13:45:14 -07:00
zpl_export.c Linux compat 2.6.39: mount_nodev() 2011-07-01 13:36:39 -07:00
zpl_file.c Linux 3.1 compat, fops->fsync() 2011-11-10 10:03:08 -08:00
zpl_inode.c Allow xattrs on symlinks 2011-11-29 10:24:24 -08:00
zpl_super.c Linux 3.3 compat, sops->show_options() 2012-02-03 10:02:01 -08:00
zpl_xattr.c Apply the ZoL coding standard to zpl_xattr.c 2012-01-12 15:12:03 -08:00
zrlock.c Export ZFS symbols needed by Lustre. 2010-09-17 16:24:15 -07:00
zvol.c Improve ZVOL queue behavior. 2012-02-07 16:23:06 -08:00