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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/drivers/md
История
Shaohua Li 12cee5a8a2 md/raid1: prevent merging too large request 
For SSD, if request size exceeds specific value (optimal io size), request size
isn't important for bandwidth. In such condition, if making request size bigger
will cause some disks idle, the total throughput will actually drop. A good
example is doing a readahead in a two-disk raid1 setup.

So when should we split big requests? We absolutly don't want to split big
request to very small requests. Even in SSD, big request transfer is more
efficient. This patch only considers request with size above optimal io size.

If all disks are busy, is it worth doing a split? Say optimal io size is 16k,
two requests 32k and two disks. We can let each disk run one 32k request, or
split the requests to 4 16k requests and each disk runs two. It's hard to say
which case is better, depending on hardware.

So only consider case where there are idle disks. For readahead, split is
always better in this case. And in my test, below patch can improve > 30%
thoughput. Hmm, not 100%, because disk isn't 100% busy.

Such case can happen not just in readahead, for example, in directio. But I
suppose directio usually will have bigger IO depth and make all disks busy, so
I ignored it.

Note: if the raid uses any hard disk, we don't prevent merging. That will make
performace worse.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
 		2012-07-31 10:03:53 +10:00
..
persistent-data dm persistent data: fix allocation failure in space map checker init 2012-07-03 12:55:37 +01:00
Kconfig dm: add verity target 2012-03-28 18:43:38 +01:00
Makefile dm: add verity target 2012-03-28 18:43:38 +01:00
bitmap.c md/bitmap: record the space available for the bitmap in the superblock. 2012-05-22 13:55:34 +10:00
bitmap.h md/bitmap: record the space available for the bitmap in the superblock. 2012-05-22 13:55:34 +10:00
dm-bio-record.h dm: preserve bi_io_vec when resubmitting bios 2009-04-02 19:55:23 +01:00
dm-bufio.c dm bufio: prefetch 2012-03-28 18:41:29 +01:00
dm-bufio.h dm bufio: prefetch 2012-03-28 18:41:29 +01:00
dm-crypt.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-delay.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-exception-store.c dm exception store: fix init error path 2012-03-28 18:41:22 +01:00
dm-exception-store.h dm snapshot: test chunk size against both origin and snapshot 2010-08-12 04:13:51 +01:00
dm-flakey.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-io.c dm io: fix discard support 2012-03-07 19:09:37 +00:00
dm-ioctl.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-kcopyd.c dm kcopyd: add dm_kcopyd_zero to zero an area 2011-10-31 20:18:58 +00:00
dm-linear.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-log-userspace-base.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
dm-log-userspace-transfer.c connector/userns: replace netlink uses of cap_raised() with capable() 2012-05-10 23:21:39 -04:00
dm-log-userspace-transfer.h dm log: userspace add luid to distinguish between concurrent log instances 2009-09-04 20:40:34 +01:00
dm-log.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-mpath.c dm mpath: allow ioctls to trigger pg init 2012-06-03 00:29:58 +01:00
dm-mpath.h dm mpath: remove is_active from struct dm_path 2008-10-10 13:36:58 +01:00
dm-path-selector.c md: Add module.h to all files using it implicitly 2011-10-31 19:31:18 -04:00
dm-path-selector.h dm mpath: add start_io and nr_bytes to path selectors 2009-06-22 10:12:27 +01:00
dm-queue-length.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-raid.c DM RAID: Use md_error() in place of simply setting Faulty bit 2012-05-22 13:55:31 +10:00
dm-raid1.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-region-hash.c Fix common misspellings 2011-03-31 11:26:23 -03:00
dm-round-robin.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-service-time.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-snap-persistent.c md: Add in export.h for files using EXPORT_SYMBOL 2011-10-31 19:31:19 -04:00
dm-snap-transient.c md: Add in export.h for files using EXPORT_SYMBOL 2011-10-31 19:31:19 -04:00
dm-snap.c dm snapshot: skip reading origin when overwriting complete chunk 2011-08-02 12:32:04 +01:00
dm-stripe.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-sysfs.c Driver core: Constify struct sysfs_ops in struct kobj_type 2010-03-07 17:04:49 -08:00
dm-table.c dm: reject trailing characters in sccanf input 2012-03-28 18:41:26 +01:00
dm-target.c dm: error return error for discards 2010-08-12 04:14:14 +01:00
dm-thin-metadata.c dm thin: provide userspace access to pool metadata 2012-06-03 00:30:01 +01:00
dm-thin-metadata.h dm thin: provide userspace access to pool metadata 2012-06-03 00:30:01 +01:00
dm-thin.c dm thin: commit metadata before creating metadata snapshot 2012-07-03 12:55:31 +01:00
dm-uevent.c md: Add in export.h for files using EXPORT_SYMBOL 2011-10-31 19:31:19 -04:00
dm-uevent.h dm: uevent generate events 2007-10-20 02:01:26 +01:00
dm-verity.c dm: add verity target 2012-03-28 18:43:38 +01:00
dm-zero.c dm: zero silently drop discards 2010-08-12 04:14:12 +01:00
dm.c dm: clear bi_end_io on remapping failure 2012-03-28 18:41:25 +01:00
dm.h dm table: add immutable feature 2011-10-31 20:19:04 +00:00
faulty.c md: tidy up rdev_for_each usage. 2012-03-19 12:46:39 +11:00
linear.c md/linear: If md_integrity_register() fails, linear_run() must free the mem. 2012-04-02 09:48:37 +10:00
linear.h md/linear: typedef removal: linear_conf_t -> struct linear_conf 2011-10-11 16:48:54 +11:00
md.c md: avoid crash when stopping md array races with closing other open fds. 2012-07-19 15:59:18 +10:00
md.h md/bitmap: add new 'space' attribute for bitmaps. 2012-05-22 13:55:07 +10:00
multipath.c md: make 'name' arg to md_register_thread non-optional. 2012-07-03 15:56:52 +10:00
multipath.h md/multipath: typedef removal: multipath_conf_t -> struct mpconf 2011-10-11 16:48:57 +11:00
raid0.c md: Avoid OOPS when reshaping raid1 to raid0 2012-04-03 15:37:26 +10:00
raid0.h md: add proper merge_bvec handling to RAID0 and Linear. 2012-03-19 12:46:39 +11:00
raid1.c md/raid1: prevent merging too large request 2012-07-31 10:03:53 +10:00
raid1.h md/raid1: prevent merging too large request 2012-07-31 10:03:53 +10:00
raid5.c raid5: add a per-stripe lock 2012-07-19 16:01:31 +10:00
raid5.h raid5: add a per-stripe lock 2012-07-19 16:01:31 +10:00
raid10.c MD RAID10: Export md_raid10_congested 2012-07-31 10:03:53 +10:00
raid10.h MD RAID10: Export md_raid10_congested 2012-07-31 10:03:53 +10:00