Andrew, Neil,
The stripe-queue patches are showing solid performance improvement.
git://lost.foo-projects.org/~dwillia2/git/iop md-for-linus
drivers/md/raid5.c | 1484
include/linux/raid/raid5.h | 87 +++-
2 files changed, 1164 insertions(+), 407 deletions(-)
Dan Williams (2):
raid5: add the stripe_queue object for tracking raid io requests (take2)
raid5: use stripe_queues to prioritize the "most deserving" requests
(take4)
I initially considered them 2.6.24 material but after fixing the sync+io
data corruption regression, fixing the large 'stripe_cache_size' values
performance regression, and seeing how well it performed on my IA
platform I would like them to be considered for 2.6.23. That being said
I have not yet tested expand operations or raid6.
Without any tuning a 4 disk (SATA) RAID5 array can reach 190MB/s. Previously
performance was around 90MB/s. Blktrace data confirms that less reads are
occurring and more writes are being merged.
$ mdadm --create /dev/md0 /dev/sd[abcd] -n 4 -l 5 --assume-clean
$ blktrace /dev/sd[abcd] &
$ for i in `seq 1 3`; do dd if=/dev/zero of=/dev/md0 bs=1024k count=1024; done
$ fg ^C
$ blkparse /dev/sda /dev/sdb /dev/sdc /dev/sdd
=pre-patch=
Total (sda):
Reads Queued: 3,136, 12,544KiB Writes Queued: 187,068, 748,272KiB
Read Dispatches: 676, 12,384KiB Write Dispatches: 30,949, 737,052KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed: 662, 12,080KiB Writes Completed: 30,630, 736,964KiB
Read Merges:2,452,9,808KiB Write Merges: 155,885, 623,540KiB
IO unplugs: 1 Timer unplugs: 1
Total (sdb):
Reads Queued: 1,541,6,164KiB Writes Queued: 91,224, 364,896KiB
Read Dispatches: 323,6,184KiB Write Dispatches: 14,603, 335,528KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed: 303,6,124KiB Writes Completed: 13,650, 328,520KiB
Read Merges:1,209,4,836KiB Write Merges: 76,080, 304,320KiB
IO unplugs: 0 Timer unplugs: 0
Total (sdc):
Reads Queued: 1,372,5,488KiB Writes Queued: 82,995, 331,980KiB
Read Dispatches: 297,5,280KiB Write Dispatches: 13,258, 304,020KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed: 268,4,948KiB Writes Completed: 12,320, 298,668KiB
Read Merges:1,067,4,268KiB Write Merges: 69,154, 276,616KiB
IO unplugs: 0 Timer unplugs: 0
Total (sdd):
Reads Queued: 1,383,5,532KiB Writes Queued: 80,186, 320,744KiB
Read Dispatches: 307,5,008KiB Write Dispatches: 13,241, 298,400KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed: 276,4,888KiB Writes Completed: 12,677, 294,324KiB
Read Merges:1,050,4,200KiB Write Merges: 66,772, 267,088KiB
IO unplugs: 0 Timer unplugs: 0
=post-patch=
Total (sda):
Reads Queued: 117, 468KiB Writes Queued: 71,511, 286,044KiB
Read Dispatches: 17, 308KiB Write Dispatches:8,412, 699,204KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed:6, 96KiB Writes Completed:3,704, 321,552KiB
Read Merges: 96, 384KiB Write Merges: 67,880, 271,520KiB
IO unplugs:14 Timer unplugs: 15
Total (sdb):
Reads Queued: 88, 352KiB Writes Queued: 56,687, 226,748KiB
Read Dispatches: 11, 288KiB Write Dispatches:8,142, 686,412KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed:8, 184KiB Writes Completed:2,770, 257,740KiB
Read Merges: 76, 304KiB Write Merges: 54,005, 216,020KiB
IO unplugs:16 Timer unplugs: 17
Total (sdc):
Reads Queued: 60, 240KiB Writes Queued: 61,863, 247,452KiB
Read Dispatches:7, 248KiB Write Dispatches:8,302, 699,832KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed:5, 144KiB Writes Completed:2,907, 258,900KiB
Read Merges: 50, 200KiB Write Merges: 58,926, 235,704KiB
IO unplugs:20 Timer unplugs: 23
Total (sdd):
Reads Queued: 61, 244KiB Writes Queued: 66,330, 265,320KiB
Read Dispatches: 10, 180KiB Write Dispatches:9,326, 694,012KiB
Reads Requeued: 0 Writes Requeued: 0
Reads Completed:4, 112KiB Writes Completed:3,562, 285,912KiB
Read Merges: 47, 188KiB Writ
