Messages in this thread | | | From | Justin TerAvest <> | Date | Mon, 28 Mar 2011 08:21:49 -0700 | Subject | Re: [RFC] [PATCH v2 0/8] Provide cgroup isolation for buffered writes. |
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On Fri, Mar 25, 2011 at 12:46 AM, Balbir Singh <balbir@linux.vnet.ibm.com> wrote: > * Justin TerAvest <teravest@google.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?
Hi Balbir,
"max observed error" is the difference between the requested weight and the observed amount of time that reached a device. Lower error values mean the isolation is more closely meeting the requested weight.
> >> >> 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?
I should add a sync prior to this; you're correct. I'll add a sync and rerun the tests when I clean up the test data for version 3 of the patchset.
> >> 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?
Before patches: iostest-write: (groupid=0, jobs=3): err= 0: pid=20654 Description : ["writer"] write: io=282444KB, bw=9410.5KB/s, iops=2352 , runt= 30014msec clat (usec): min=3 , max=28921K, avg=1468.79, stdev=108833.25 lat (usec): min=3 , max=28921K, avg=1468.89, stdev=108833.25 bw (KB/s) : min= 101, max= 5448, per=21.39%, avg=2013.25, stdev=1322.76 cpu : usr=0.11%, sys=0.41%, ctx=77, majf=0, minf=81 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=0/70611/0, short=0/0/0 lat (usec): 4=0.65%, 10=95.27%, 20=1.39%, 50=2.58%, 100=0.01% lat (usec): 250=0.01% lat (msec): 2=0.01%, 4=0.01%, 10=0.04%, 20=0.02%, 100=0.01% lat (msec): 250=0.01%, 500=0.01%, 750=0.01%, >=2000=0.01%
Run status group 0 (all jobs): WRITE: io=282444KB, aggrb=9410KB/s, minb=9636KB/s, maxb=9636KB/s, mint=30014msec, maxt=30014msec
Disk stats (read/write): sdb: ios=3716/0, merge=0/0, ticks=157011/0, in_queue=506264, util=99.09%
After patches: Jobs: 3 (f=3): [WWW] [100.0% done] [0K/0K /s] [0 /0 iops] [eta 00m:00s] iostest-write: (groupid=0, jobs=3): err= 0: pid=14178 Description : ["writer"] write: io=90268KB, bw=3004.9KB/s, iops=751 , runt= 30041msec clat (usec): min=3 , max=29612K, avg=4086.42, stdev=197096.83 lat (usec): min=3 , max=29612K, avg=4086.53, stdev=197096.83 bw (KB/s) : min= 956, max= 1092, per=32.58%, avg=978.67, stdev= 0.00 cpu : usr=0.03%, sys=0.14%, ctx=44, majf=1, minf=83 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=0/22567/0, short=0/0/0 lat (usec): 4=1.06%, 10=94.20%, 20=2.11%, 50=2.50%, 100=0.01% lat (usec): 250=0.01% lat (msec): 10=0.04%, 20=0.03%, 50=0.01%, 250=0.01%, >=2000=0.01%
Run status group 0 (all jobs): WRITE: io=90268KB, aggrb=3004KB/s, minb=3076KB/s, maxb=3076KB/s, mint=30041msec, maxt=30041msec
Disk stats (read/write): sdb: ios=4158/0, merge=0/0, ticks=95747/0, in_queue=475051, util=100.00%
Thanks, Justin
> > -- > Three Cheers, > Balbir > -- > 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/ > -- 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/
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