Re: How can I boost block I/O performance

From: Avi Kivity
Date: Mon May 08 2006 - 11:50:10 EST


Dave Pitts wrote:

OK, I ran some tests, bypassing NFS, and got the following vmstat display:

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
4 1 696 80692 844 7225424 0 0 92 263924 14380 6176 2 40 46 12
6 0 696 108668 784 7200936 0 0 456 6444 30515 20641 3 57 36 3
5 1 696 100916 768 7211220 0 0 508 97276 31761 19916 3 65 27 4
7 0 700 91188 764 7217340 0 0 428 121576 28704 21957 3 69 24 3
3 3 700 103356 780 7204472 0 0 408 121748 29513 22603 3 66 23 8
7 0 700 92836 780 7216168 0 0 360 43508 28784 21410 3 54 33 11
7 0 700 88364 768 7224272 0 0 296 158236 26530 17570 3 66 21 10
10 0 700 91068 776 7219096 0 0 444 141456 30306 16053 3 74 16 7
5 2 700 102212 752 7206676 0 0 340 170076 29249 14872 2 69 19 10
11 0 700 87884 768 7222096 0 0 392 143312 29743 19808 1 65 23 11
8 0 700 104692 744 7204644 0 0 240 159624 25814 18747 3 58 20 19
9 0 700 107196 736 7205196 0 0 344 148500 28191 18113 3 70 21 6
16 1 700 99300 768 7211364 0 12 464 164348 25671 18326 4 64 18 15
5 4 700 107412 1052 7204824 0 0 936 170904 28994 17062 3 73 11 14
8 1 700 98892 1284 7217512 0 0 596 182708 31520 18424 1 76 13 10

This ia with 6 concurrent data streams. In addition to the /proc/sys/vm/dirty* values I also adjusted
values in mm/page-writeback.c eg. MAX_WRITEBACK_PAGES to 8192 . Our goal is to blast out
as much as possible per pdflush invocation.


These are healthier numbers. How many disks are on that machine? What raid level? Does it have battery backed up cache?

Anyway you need to check you network, since it looks like block throughput is not the issue.

--
error compiling committee.c: too many arguments to function

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