Messages in this thread | | | Subject | fio sync read 4k block size 35% regression | From | "Zhang, Yanmin" <> | Date | Wed, 01 Jul 2009 11:25:33 +0800 |
| |
Comapraing with 2.6.30, fio sync read (block size 4k) has about 35% regression with kernel 2.6.31-rc1 on my stoakley machine with a JBOD (13 SCSI disks).
Every disk has 1 partition and 4 1-GB files. Start 10 processes per disk to do sync read sequentinally.
Bisected down to below patch.
51daa88ebd8e0d437289f589af29d4b39379ea76 is first bad commit commit 51daa88ebd8e0d437289f589af29d4b39379ea76 Author: Wu Fengguang <fengguang.wu@intel.com> Date: Tue Jun 16 15:31:24 2009 -0700
readahead: remove sync/async readahead call dependency
The readahead call scheme is error-prone in that it expects the call sites to check for async readahead after doing a sync one. I.e.
if (!page) page_cache_sync_readahead(); page = find_get_page(); if (page && PageReadahead(page)) page_cache_async_readahead();
I also test block size 64k and 128k, but they don't have regression. Perhaps the default read_ahead_kb is equal to 128?
Other 2 machines have no such regression. The JBODS of the 2 machines consists of 12 and 7 SATA/SAS disks while every disk has 2 partitions.
-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |