On Thu, Apr 16, 2009 at 10:11:39PM -0400, Vivek Goyal wrote: > On Thu, Apr 16, 2009 at 04:57:20PM -0400, Vivek Goyal wrote: > > On Mon, Apr 13, 2009 at 01:05:52PM +0900, Ryo Tsuruta wrote: > > > Hi Alasdair and all, > > > > > > I did more tests on dm-ioband and I've posted the test items and > > > results on my website. The results are very good. > > > http://people.valinux.co.jp/~ryov/dm-ioband/test/test-items.xls > > > > > > I hope someone will test dm-ioband and report back to the dm-devel > > > mailing list. > > > > > > > Ok, one more test. This time to show that with single queue and FIFO > dispatch a writer can easily starve the reader. > > I have created two partitions /dev/sda1 and /dev/sda2. Two ioband devices > ioband1 and ioband2 on /dev/sda1 and /dev/sda2 respectively with weights > 40 and 20. > > I am launching an aggressive writer dd with prio 7 (Best effort) and a > reader with prio 0 (Best effort). > > Following is my script. > > **************************************************************** > rm /mnt/sdd1/aggressivewriter > > sync > echo 3 > /proc/sys/vm/drop_caches > > #launch an hostile writer > ionice -c2 -n7 dd if=/dev/zero of=/mnt/sdd1/aggressivewriter bs=4K count=524288 conv=fdatasync & > > # Reader > ionice -c 2 -n 0 dd if=/mnt/sdd1/testzerofile1 of=/dev/null & > wait $! > echo "reader finished" > ********************************************************************** More results. Same reader writer test as above, the only variation I have done is change the class of reader to RT from BE. ionice -c 1 -n 0 dd if=/mnt/sdd1/testzerofile1 of=/dev/null & Even chaning the class of reader does not help. Writer still starves the reader. Without dm-ioband ================= First run 2147483648 bytes (2.1 GB) copied, 43.9096 s, 48.9 MB/s (Reader) reader finished 2147483648 bytes (2.1 GB) copied, 85.9094 s, 25.0 MB/s (Writer) Second run 2147483648 bytes (2.1 GB) copied, 40.2446 s, 53.4 MB/s (Reader) reader finished 2147483648 bytes (2.1 GB) copied, 82.723 s, 26.0 MB/s (Writer) With dm-ioband ============== First run 2147483648 bytes (2.1 GB) copied, 69.0272 s, 31.1 MB/s (Writer) 2147483648 bytes (2.1 GB) copied, 89.3037 s, 24.0 MB/s (Reader) reader finished Second run 2147483648 bytes (2.1 GB) copied, 64.8751 s, 33.1 MB/s (Writer) 2147483648 bytes (2.1 GB) copied, 89.0273 s, 24.1 MB/s (Reader) reader finished Thanks Vivek -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
