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Date: Fri, 25 Mar 2011 13:16:35 +0530 From: Balbir Singh <balbir@...ux.vnet.ibm.com> To: Justin TerAvest <teravest@...gle.com> Cc: vgoyal@...hat.com, jaxboe@...ionio.com, m-ikeda@...jp.nec.com, ryov@...inux.co.jp, taka@...inux.co.jp, kamezawa.hiroyu@...fujitsu.com, righi.andrea@...il.com, guijianfeng@...fujitsu.com, ctalbott@...gle.com, linux-kernel@...r.kernel.org Subject: Re: [RFC] [PATCH v2 0/8] Provide cgroup isolation for buffered writes. * Justin TerAvest <teravest@...gle.com> [2011-03-22 16:08:47]: > This patchset adds tracking to the page_cgroup structure for which cgroup has > dirtied a page, and uses that information to provide isolation between > cgroups performing writeback. > > I know that there is some discussion to remove request descriptor limits > entirely, but I included a patch to introduce per-cgroup limits to enable > this functionality. Without it, we didn't see much isolation improvement. > > I think most of this material has been discussed on lkml previously, this is > just another attempt to make a patchset that handles buffered writes for CFQ. > > There was a lot of previous discussion at: > http://thread.gmane.org/gmane.linux.kernel/1007922 > > Thanks to Andrea Righi, Kamezawa Hiroyuki, Munehiro Ikeda, Nauman Rafique, > and Vivek Goyal for work on previous versions of these patches. > > For version 2: > - I collected more statistics and provided data in the cover sheet > - blkio id is now stored inside "flags" in page_cgroup, with cmpxchg > - I cleaned up some patch names > - Added symmetric reference wrappers in cfq-iosched > > There are a couple lingering issues that exist in this patchset-- it's meant > to be an RFC to discuss the overall design for tracking of buffered writes. > I have at least a couple of patches to finish to make absolutely sure that > refcounts and locking are handled properly, I just need to do more testing. > > Documentation/block/biodoc.txt | 10 + > block/blk-cgroup.c | 203 +++++++++++++++++- > block/blk-cgroup.h | 9 +- > block/blk-core.c | 218 +++++++++++++------ > block/blk-settings.c | 2 +- > block/blk-sysfs.c | 59 +++--- > block/cfq-iosched.c | 473 ++++++++++++++++++++++++++++++---------- > block/cfq.h | 6 +- > block/elevator.c | 7 +- > fs/buffer.c | 2 + > fs/direct-io.c | 2 + > include/linux/blk_types.h | 2 + > include/linux/blkdev.h | 81 +++++++- > include/linux/blkio-track.h | 89 ++++++++ > include/linux/elevator.h | 14 +- > include/linux/iocontext.h | 1 + > include/linux/memcontrol.h | 6 + > include/linux/mmzone.h | 4 +- > include/linux/page_cgroup.h | 38 +++- > init/Kconfig | 16 ++ > mm/Makefile | 3 +- > mm/bounce.c | 2 + > mm/filemap.c | 2 + > mm/memcontrol.c | 6 + > mm/memory.c | 6 + > mm/page-writeback.c | 14 +- > mm/page_cgroup.c | 29 ++- > mm/swap_state.c | 2 + > 28 files changed, 1066 insertions(+), 240 deletions(-) > > > 8f0b0f4 cfq: Don't allow preemption across cgroups > a47cdc6 block: Per cgroup request descriptor counts > 8dd7adb cfq: add per cgroup writeout done by flusher stat > 1fa0b6d cfq: Fix up tracked async workload length. > e9e85d3 block: Modify CFQ to use IO tracking information. > f8ffb19 cfq-iosched: Make async queues per cgroup > 1d9ee09 block,fs,mm: IO cgroup tracking for buffered write > 31c7321 cfq-iosched: add symmetric reference wrappers > > > ===================================== Isolation experiment results > > For isolation testing, we run a test that's available at: > git://google3-2.osuosl.org/tests/blkcgroup.git > > It creates containers, runs workloads, and checks to see how well we meet > isolation targets. For the purposes of this patchset, I only ran > tests among buffered writers. > > Before patches > ============== > 10:32:06 INFO experiment 0 achieved DTFs: 666, 333 > 10:32:06 INFO experiment 0 FAILED: max observed error is 167, allowed is 150 > 10:32:51 INFO experiment 1 achieved DTFs: 647, 352 > 10:32:51 INFO experiment 1 FAILED: max observed error is 253, allowed is 150 > 10:33:35 INFO experiment 2 achieved DTFs: 298, 701 > 10:33:35 INFO experiment 2 FAILED: max observed error is 199, allowed is 150 > 10:34:19 INFO experiment 3 achieved DTFs: 445, 277, 277 > 10:34:19 INFO experiment 3 FAILED: max observed error is 155, allowed is 150 > 10:35:05 INFO experiment 4 achieved DTFs: 418, 104, 261, 215 > 10:35:05 INFO experiment 4 FAILED: max observed error is 232, allowed is 150 > 10:35:53 INFO experiment 5 achieved DTFs: 213, 136, 68, 102, 170, 136, 170 > 10:35:53 INFO experiment 5 PASSED: max observed error is 73, allowed is 150 > 10:36:04 INFO -----ran 6 experiments, 1 passed, 5 failed > > After patches > ============= > 11:05:22 INFO experiment 0 achieved DTFs: 501, 498 > 11:05:22 INFO experiment 0 PASSED: max observed error is 2, allowed is 150 > 11:06:07 INFO experiment 1 achieved DTFs: 874, 125 > 11:06:07 INFO experiment 1 PASSED: max observed error is 26, allowed is 150 > 11:06:53 INFO experiment 2 achieved DTFs: 121, 878 > 11:06:53 INFO experiment 2 PASSED: max observed error is 22, allowed is 150 > 11:07:46 INFO experiment 3 achieved DTFs: 589, 205, 204 > 11:07:46 INFO experiment 3 PASSED: max observed error is 11, allowed is 150 > 11:08:34 INFO experiment 4 achieved DTFs: 616, 109, 109, 163 > 11:08:34 INFO experiment 4 PASSED: max observed error is 34, allowed is 150 > 11:09:29 INFO experiment 5 achieved DTFs: 139, 139, 139, 139, 140, 141, 160 > 11:09:29 INFO experiment 5 PASSED: max observed error is 1, allowed is 150 > 11:09:46 INFO -----ran 6 experiments, 6 passed, 0 failed Could you explain what max observed errors is all about? > > Summary > ======= > Isolation between buffered writers is clearly better with this patch. > > > =============================== Read latency results > To test read latency, I created two containers: > - One called "readers", with weight 900 > - One called "writers", with weight 100 > > I ran this fio workload in "readers": > [global] > directory=/mnt/iostestmnt/fio > runtime=30 > time_based=1 > group_reporting=1 > exec_prerun='echo 3 > /proc/sys/vm/drop_caches' Is this sufficient, do you need a sync prior to this? > cgroup_nodelete=1 > bs=4K > size=512M > > [iostest-read] > description="reader" > numjobs=16 > rw=randread > new_group=1 > > > ....and this fio workload in "writers" > [global] > directory=/mnt/iostestmnt/fio > runtime=30 > time_based=1 > group_reporting=1 > exec_prerun='echo 3 > /proc/sys/vm/drop_caches' > cgroup_nodelete=1 > bs=4K > size=512M > > [iostest-write] > description="writer" > cgroup=writers > numjobs=3 > rw=write > new_group=1 > > > > I've pasted the results from the "read" workload inline. > > Before patches > ============== > Starting 16 processes > > Jobs: 14 (f=14): [_rrrrrr_rrrrrrrr] [36.2% done] [352K/0K /s] [86 /0 iops] [eta 01m:00s]············· > iostest-read: (groupid=0, jobs=16): err= 0: pid=20606 > Description : ["reader"] > read : io=13532KB, bw=455814 B/s, iops=111 , runt= 30400msec > clat (usec): min=2190 , max=30399K, avg=30395175.13, stdev= 0.20 > lat (usec): min=2190 , max=30399K, avg=30395177.07, stdev= 0.20 > bw (KB/s) : min= 0, max= 260, per=0.00%, avg= 0.00, stdev= 0.00 > cpu : usr=0.00%, sys=0.03%, ctx=3691, majf=2, minf=468 > IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% > submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% > complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% > issued r/w/d: total=3383/0/0, short=0/0/0 > > lat (msec): 4=0.03%, 10=2.66%, 20=74.84%, 50=21.90%, 100=0.09% > lat (msec): 250=0.06%, >=2000=0.41% > > Run status group 0 (all jobs): > READ: io=13532KB, aggrb=445KB/s, minb=455KB/s, maxb=455KB/s, mint=30400msec, maxt=30400msec > > Disk stats (read/write): > sdb: ios=3744/18, merge=0/16, ticks=542713/1675, in_queue=550714, util=99.15% > > > > After patches > ============= > tarting 16 processes > Jobs: 16 (f=16): [rrrrrrrrrrrrrrrr] [100.0% done] [557K/0K /s] [136 /0 iops] [eta 00m:00s] > iostest-read: (groupid=0, jobs=16): err= 0: pid=14183 > Description : ["reader"] > read : io=14940KB, bw=506105 B/s, iops=123 , runt= 30228msec > clat (msec): min=2 , max=29866 , avg=463.42, stdev=101.84 > lat (msec): min=2 , max=29866 , avg=463.42, stdev=101.84 > bw (KB/s) : min= 0, max= 198, per=31.69%, avg=156.52, stdev=17.83 > cpu : usr=0.01%, sys=0.03%, ctx=4274, majf=2, minf=464 > IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% > submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% > complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% > issued r/w/d: total=3735/0/0, short=0/0/0 > > lat (msec): 4=0.05%, 10=0.32%, 20=32.99%, 50=64.61%, 100=1.26% > lat (msec): 250=0.11%, 500=0.11%, 750=0.16%, 1000=0.05%, >=2000=0.35% > > Run status group 0 (all jobs): > READ: io=14940KB, aggrb=494KB/s, minb=506KB/s, maxb=506KB/s, mint=30228msec, maxt=30228msec > > Disk stats (read/write): > sdb: ios=4189/0, merge=0/0, ticks=96428/0, in_queue=478798, util=100.00% > This shows an improvement in read b/w, what does the writer output look like? -- Three Cheers, Balbir -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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