On Mon, Jun 22, 2009 at 12:06:42PM -0400, Jeff Moyer wrote: > Vivek Goyal <vgoyal@xxxxxxxxxx> writes: > > > On Mon, Jun 22, 2009 at 11:40:42AM -0400, Jeff Moyer wrote: > >> Vivek Goyal <vgoyal@xxxxxxxxxx> writes: > >> > >> > On Sun, Jun 21, 2009 at 08:51:16PM +0530, Balbir Singh wrote: > >> >> * Vivek Goyal <vgoyal@xxxxxxxxxx> [2009-06-19 16:37:18]: > >> >> > >> >> > > >> >> > Hi All, > >> >> > > >> >> > Here is the V5 of the IO controller patches generated on top of 2.6.30. > >> >> [snip] > >> >> > >> >> > Testing > >> >> > ======= > >> >> > > >> >> > >> >> [snip] > >> >> > >> >> I've not been reading through the discussions in complete detail, but > >> >> I see no reference to async reads or aio. In the case of aio, aio > >> >> presumes the context of the user space process. Could you elaborate on > >> >> any testing you've done with these cases? > >> >> > >> > > >> > Hi Balbir, > >> > > >> > So far I had not done any testing with AIO. I have done some just now. > >> > Here are the results. > >> > > >> > Test1 (AIO reads) > >> > ================ > >> > Set up two fio, AIO read jobs in two cgroup with weight 1000 and 500 > >> > respectively. I am using cfq scheduler. Following are some lines from my test > >> > script. > >> > > >> > =================================================================== > >> > fio_args="--ioengine=libaio --rw=read --size=512M" > >> > >> AIO doesn't make sense without O_DIRECT. > >> > > > > Ok, here are the read results with --direct=1 for reads. In previous posting, > > writes were already direct. > > > > test1 statistics: time=8 16 20796 sectors=8 16 1049648 > > test2 statistics: time=8 16 10551 sectors=8 16 581160 > > > > > > Not sure why reads are so slow with --direct=1? In the previous test > > (no direct IO), I had cleared the caches using > > (echo 3 > /proc/sys/vm/drop_caches) so reads could not have come from page > > cache? > > O_DIRECT bypasses the page cache, and hence the readahead code. Try > driving deeper queue depths and/or using larger I/O sizes. Ok. Thanks. I tried increasing iodepth to 20 and it helped a lot. test1 statistics: time=8 16 6672 sectors=8 16 1049656 test2 statistics: time=8 16 3508 sectors=8 16 583432 Thanks Vivek -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
