Can you try echo 1 > /proc/sys/net/ipv4/tcp_low_latency And see if it improves things? I remember there being an option to disable nagle completely, but it's gone apparently. Jan > On 11 Sep 2015, at 10:43, Nick Fisk <nick@xxxxxxxxxx> wrote: > > > > > >> -----Original Message----- >> From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of >> Somnath Roy >> Sent: 11 September 2015 06:23 >> To: Rafael Lopez <rafael.lopez@xxxxxxxxxx> >> Cc: ceph-users@xxxxxxxxxxxxxx >> Subject: Re: bad perf for librbd vs krbd using FIO >> >> That’s probably because the krbd version you are using doesn’t have the >> TCP_NODELAY patch. We have submitted it (and you can build it from latest >> rbd source) , but, I am not sure when it will be in linux mainline. > > From memory it landed in 3.19, but there are also several issues with max IO size, max nr_requests and readahead. I would suggest for testing, try one of these:- > > http://gitbuilder.ceph.com/kernel-deb-precise-x86_64-basic/ref/ra-bring-back/ > > >> >> Thanks & Regards >> Somnath >> >> From: Rafael Lopez [mailto:rafael.lopez@xxxxxxxxxx] >> Sent: Thursday, September 10, 2015 10:12 PM >> To: Somnath Roy >> Cc: ceph-users@xxxxxxxxxxxxxx >> Subject: Re: bad perf for librbd vs krbd using FIO >> >> Ok I ran the two tests again with direct=1, smaller block size (4k) and smaller >> total io (100m), disabled cache at ceph.conf side on client by adding: >> >> [client] >> rbd cache = false >> rbd cache max dirty = 0 >> rbd cache size = 0 >> rbd cache target dirty = 0 >> >> >> The result seems to have swapped around, now the librbd job is running >> ~50% faster than the krbd job! >> >> ####### krbd job: >> >> [root@rcprsdc1r72-01-ac rafaell]# fio ext4_test >> job1: (g=0): rw=rw, bs=4K-4K/4K-4K/4K-4K, ioengine=sync, iodepth=16 >> fio-2.2.8 >> Starting 1 process >> Jobs: 1 (f=1): [W(1)] [100.0% done] [0KB/571KB/0KB /s] [0/142/0 iops] [eta >> 00m:00s] >> job1: (groupid=0, jobs=1): err= 0: pid=29095: Fri Sep 11 14:48:21 2015 >> write: io=102400KB, bw=647137B/s, iops=157, runt=162033msec >> clat (msec): min=2, max=25, avg= 6.32, stdev= 1.21 >> lat (msec): min=2, max=25, avg= 6.32, stdev= 1.21 >> clat percentiles (usec): >> | 1.00th=[ 2896], 5.00th=[ 4320], 10.00th=[ 4768], 20.00th=[ 5536], >> | 30.00th=[ 5920], 40.00th=[ 6176], 50.00th=[ 6432], 60.00th=[ 6624], >> | 70.00th=[ 6816], 80.00th=[ 7136], 90.00th=[ 7584], 95.00th=[ 7968], >> | 99.00th=[ 9024], 99.50th=[ 9664], 99.90th=[15808], 99.95th=[17536], >> | 99.99th=[19328] >> bw (KB /s): min= 506, max= 1171, per=100.00%, avg=632.22, stdev=104.77 >> lat (msec) : 4=2.88%, 10=96.69%, 20=0.43%, 50=0.01% >> cpu : usr=0.17%, sys=0.71%, ctx=25634, majf=0, minf=35 >> 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 : total=r=0/w=25600/d=0, short=r=0/w=0/d=0, >> drop=r=0/w=0/d=0 >> latency : target=0, window=0, percentile=100.00%, depth=16 >> >> Run status group 0 (all jobs): >> WRITE: io=102400KB, aggrb=631KB/s, minb=631KB/s, maxb=631KB/s, >> mint=162033msec, maxt=162033msec >> >> Disk stats (read/write): >> rbd0: ios=0/25638, merge=0/32, ticks=0/160765, in_queue=160745, >> util=99.11% >> [root@rcprsdc1r72-01-ac rafaell]# >> >> ###### librb job: >> >> [root@rcprsdc1r72-01-ac rafaell]# fio fio_rbd_test >> job1: (g=0): rw=rw, bs=4K-4K/4K-4K/4K-4K, ioengine=rbd, iodepth=16 >> fio-2.2.8 >> Starting 1 process >> rbd engine: RBD version: 0.1.9 >> Jobs: 1 (f=1): [W(1)] [100.0% done] [0KB/703KB/0KB /s] [0/175/0 iops] [eta >> 00m:00s] >> job1: (groupid=0, jobs=1): err= 0: pid=30568: Fri Sep 11 14:50:24 2015 >> write: io=102400KB, bw=950141B/s, iops=231, runt=110360msec >> slat (usec): min=70, max=992, avg=115.05, stdev=30.07 >> clat (msec): min=13, max=117, avg=67.91, stdev=24.93 >> lat (msec): min=13, max=117, avg=68.03, stdev=24.93 >> clat percentiles (msec): >> | 1.00th=[ 19], 5.00th=[ 26], 10.00th=[ 38], 20.00th=[ 40], >> | 30.00th=[ 46], 40.00th=[ 62], 50.00th=[ 77], 60.00th=[ 85], >> | 70.00th=[ 88], 80.00th=[ 91], 90.00th=[ 95], 95.00th=[ 99], >> | 99.00th=[ 105], 99.50th=[ 110], 99.90th=[ 116], 99.95th=[ 117], >> | 99.99th=[ 118] >> bw (KB /s): min= 565, max= 3174, per=100.00%, avg=935.74, stdev=407.67 >> lat (msec) : 20=2.41%, 50=29.85%, 100=64.46%, 250=3.29% >> cpu : usr=2.43%, sys=0.29%, ctx=7847, majf=0, minf=2750 >> IO depths : 1=6.2%, 2=12.5%, 4=25.0%, 8=50.0%, 16=6.2%, 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=94.1%, 8=0.0%, 16=5.9%, 32=0.0%, 64=0.0%, >>> =64=0.0% >> issued : total=r=0/w=25600/d=0, short=r=0/w=0/d=0, >> drop=r=0/w=0/d=0 >> latency : target=0, window=0, percentile=100.00%, depth=16 >> >> Run status group 0 (all jobs): >> WRITE: io=102400KB, aggrb=927KB/s, minb=927KB/s, maxb=927KB/s, >> mint=110360msec, maxt=110360msec >> >> Disk stats (read/write): >> dm-1: ios=240/369, merge=0/0, ticks=742/40, in_queue=782, util=0.38%, >> aggrios=240/379, aggrmerge=0/19, aggrticks=742/41, aggrin_queue=783, >> aggrutil=0.39% >> sda: ios=240/379, merge=0/19, ticks=742/41, in_queue=783, util=0.39% >> [root@rcprsdc1r72-01-ac rafaell]# >> >> >> >> Confirmed speed (at least for krbd) using dd: >> [root@rcprsdc1r72-01-ac rafaell]# dd if=/mnt/ssd/random100g >> of=/mnt/rbd/dd_io_test bs=4k count=10000 oflag=direct >> 10000+0 records in >> 10000+0 records out >> 40960000 bytes (41 MB) copied, 64.9799 s, 630 kB/s >> [root@rcprsdc1r72-01-ac rafaell]# >> >> >> Back to FIO, it's worse for 1M block size (librbd is about ~100% better perf). >> 1M librbd: >> Run status group 0 (all jobs): >> WRITE: io=1024.0MB, aggrb=112641KB/s, minb=112641KB/s, >> maxb=112641KB/s, mint=9309msec, maxt=9309msec >> >> 1M krbd: >> Run status group 0 (all jobs): >> WRITE: io=1024.0MB, aggrb=49939KB/s, minb=49939KB/s, maxb=49939KB/s, >> mint=20997msec, maxt=20997msec >> >> Raf >> >> On 11 September 2015 at 14:33, Somnath Roy <Somnath.Roy@xxxxxxxxxxx> >> wrote: >> Only changing client side ceph.conf and rerunning the tests is sufficient. >> >> Thanks & Regards >> Somnath >> >> From: Rafael Lopez [mailto:rafael.lopez@xxxxxxxxxx] >> Sent: Thursday, September 10, 2015 8:58 PM >> To: Somnath Roy >> Cc: ceph-users@xxxxxxxxxxxxxx >> Subject: Re: bad perf for librbd vs krbd using FIO >> >> Thanks for the quick reply Somnath, will give this a try. >> >> In order to set the rbd cache settings, is it a matter of updating the ceph.conf >> file on the client only prior to running the test, or do I need to inject args to all >> OSDs ? >> >> Raf >> >> >> On 11 September 2015 at 13:39, Somnath Roy <Somnath.Roy@xxxxxxxxxxx> >> wrote: >> It may be due to rbd cache effect.. >> Try the following.. >> >> Run your test with direct = 1 both the cases and rbd_cache = false (disable all >> other rbd cache option as well). This should give you similar result like krbd. >> >> In direct =1 case, we saw ~10-20% degradation if we make rbd_cache = true. >> But, direct = 0 case, it could be more as you are seeing.. >> >> I think there is a delta (or need to tune properly) if you want to use rbd >> cache. >> >> Thanks & Regards >> Somnath >> >> >> >> From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of >> Rafael Lopez >> Sent: Thursday, September 10, 2015 8:24 PM >> To: ceph-users@xxxxxxxxxxxxxx >> Subject: bad perf for librbd vs krbd using FIO >> >> Hi all, >> >> I am seeing a big discrepancy between librbd and kRBD/ext4 performance >> using FIO with single RBD image. RBD images are coming from same RBD >> pool, same size and settings for both. The librbd results are quite bad by >> comparison, and in addition if I scale up the kRBD FIO job with more >> jobs/threads it increases up to 3-4x results below, but librbd doesn't seem to >> scale much at all. I figured that it should be close to the kRBD result for a >> single job/thread before parallelism comes into play though. RBD cache >> settings are all default. >> >> I can see some obvious differences in FIO output, but not being well versed >> with FIO I'm not sure what to make of it or where to start diagnosing the >> discrepancy. Hunted around but haven't found anything useful, any >> suggestions/insights would be appreciated. >> >> RBD cache settings: >> [root@rcmktdc1r72-09-ac rafaell]# ceph --admin-daemon >> /var/run/ceph/ceph-osd.659.asok config show | grep rbd_cache >> "rbd_cache": "true", >> "rbd_cache_writethrough_until_flush": "true", >> "rbd_cache_size": "33554432", >> "rbd_cache_max_dirty": "25165824", >> "rbd_cache_target_dirty": "16777216", >> "rbd_cache_max_dirty_age": "1", >> "rbd_cache_max_dirty_object": "0", >> "rbd_cache_block_writes_upfront": "false", >> [root@rcmktdc1r72-09-ac rafaell]# >> >> This is the FIO job file for the kRBD job: >> >> [root@rcprsdc1r72-01-ac rafaell]# cat ext4_test >> ; -- start job file -- >> [global] >> rw=rw >> size=100g >> filename=/mnt/rbd/fio_test_file_ext4 >> rwmixread=0 >> rwmixwrite=100 >> percentage_random=0 >> bs=1024k >> direct=0 >> iodepth=16 >> thread=1 >> numjobs=1 >> [job1] >> ; -- end job file -- >> >> [root@rcprsdc1r72-01-ac rafaell]# >> >> This is the FIO job file for the librbd job: >> >> [root@rcprsdc1r72-01-ac rafaell]# cat fio_rbd_test >> ; -- start job file -- >> [global] >> rw=rw >> size=100g >> rwmixread=0 >> rwmixwrite=100 >> percentage_random=0 >> bs=1024k >> direct=0 >> iodepth=16 >> thread=1 >> numjobs=1 >> ioengine=rbd >> rbdname=nas1-rds-stg31 >> pool=rbd >> [job1] >> ; -- end job file -- >> >> >> Here are the results: >> >> [root@rcprsdc1r72-01-ac rafaell]# fio ext4_test >> job1: (g=0): rw=rw, bs=1M-1M/1M-1M/1M-1M, ioengine=sync, iodepth=16 >> fio-2.2.8 >> Starting 1 thread >> job1: Laying out IO file(s) (1 file(s) / 102400MB) >> Jobs: 1 (f=1): [W(1)] [100.0% done] [0KB/321.7MB/0KB /s] [0/321/0 iops] [eta >> 00m:00s] >> job1: (groupid=0, jobs=1): err= 0: pid=37981: Fri Sep 11 12:33:13 2015 >> write: io=102400MB, bw=399741KB/s, iops=390, runt=262314msec >> clat (usec): min=411, max=574082, avg=2492.91, stdev=7316.96 >> lat (usec): min=418, max=574113, avg=2520.12, stdev=7318.53 >> clat percentiles (usec): >> | 1.00th=[ 446], 5.00th=[ 458], 10.00th=[ 474], 20.00th=[ 510], >> | 30.00th=[ 1064], 40.00th=[ 1096], 50.00th=[ 1160], 60.00th=[ 1320], >> | 70.00th=[ 1592], 80.00th=[ 2448], 90.00th=[ 7712], 95.00th=[ 7904], >> | 99.00th=[11072], 99.50th=[11712], 99.90th=[13120], 99.95th=[73216], >> | 99.99th=[464896] >> bw (KB /s): min= 264, max=2156544, per=100.00%, avg=412986.27, >> stdev=375092.66 >> lat (usec) : 500=18.68%, 750=7.43%, 1000=2.11% >> lat (msec) : 2=48.89%, 4=4.35%, 10=16.79%, 20=1.67%, 50=0.03% >> lat (msec) : 100=0.03%, 250=0.02%, 500=0.01%, 750=0.01% >> cpu : usr=1.24%, sys=45.38%, ctx=19298, majf=0, minf=974 >> 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 : total=r=0/w=102400/d=0, short=r=0/w=0/d=0, >> drop=r=0/w=0/d=0 >> latency : target=0, window=0, percentile=100.00%, depth=16 >> >> Run status group 0 (all jobs): >> WRITE: io=102400MB, aggrb=399740KB/s, minb=399740KB/s, >> maxb=399740KB/s, mint=262314msec, maxt=262314msec >> >> Disk stats (read/write): >> rbd0: ios=0/150890, merge=0/49, ticks=0/36117700, in_queue=36145277, >> util=96.97% >> [root@rcprsdc1r72-01-ac rafaell]# >> >> [root@rcprsdc1r72-01-ac rafaell]# fio fio_rbd_test >> job1: (g=0): rw=rw, bs=1M-1M/1M-1M/1M-1M, ioengine=rbd, iodepth=16 >> fio-2.2.8 >> Starting 1 thread >> rbd engine: RBD version: 0.1.9 >> Jobs: 1 (f=1): [W(1)] [100.0% done] [0KB/65405KB/0KB /s] [0/63/0 iops] [eta >> 00m:00s] >> job1: (groupid=0, jobs=1): err= 0: pid=43960: Fri Sep 11 12:54:25 2015 >> write: io=102400MB, bw=121882KB/s, iops=119, runt=860318msec >> slat (usec): min=355, max=7300, avg=908.97, stdev=361.02 >> clat (msec): min=11, max=1468, avg=129.59, stdev=130.68 >> lat (msec): min=12, max=1468, avg=130.50, stdev=130.69 >> clat percentiles (msec): >> | 1.00th=[ 21], 5.00th=[ 26], 10.00th=[ 29], 20.00th=[ 34], >> | 30.00th=[ 37], 40.00th=[ 40], 50.00th=[ 44], 60.00th=[ 63], >> | 70.00th=[ 233], 80.00th=[ 241], 90.00th=[ 269], 95.00th=[ 367], >> | 99.00th=[ 553], 99.50th=[ 652], 99.90th=[ 832], 99.95th=[ 848], >> | 99.99th=[ 1369] >> bw (KB /s): min=20363, max=248543, per=100.00%, avg=124381.19, >> stdev=42313.29 >> lat (msec) : 20=0.95%, 50=55.27%, 100=5.55%, 250=24.83%, 500=12.28% >> lat (msec) : 750=0.89%, 1000=0.21%, 2000=0.01% >> cpu : usr=9.58%, sys=1.15%, ctx=23883, majf=0, minf=2751023 >> IO depths : 1=1.2%, 2=3.0%, 4=9.7%, 8=68.3%, 16=17.8%, 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=92.5%, 8=4.3%, 16=3.2%, 32=0.0%, 64=0.0%, >>> =64=0.0% >> issued : total=r=0/w=102400/d=0, short=r=0/w=0/d=0, >> drop=r=0/w=0/d=0 >> latency : target=0, window=0, percentile=100.00%, depth=16 >> >> Run status group 0 (all jobs): >> WRITE: io=102400MB, aggrb=121882KB/s, minb=121882KB/s, >> maxb=121882KB/s, mint=860318msec, maxt=860318msec >> >> Disk stats (read/write): >> dm-1: ios=0/2072, merge=0/0, ticks=0/233, in_queue=233, util=0.01%, >> aggrios=1/2249, aggrmerge=7/559, aggrticks=9/254, aggrin_queue=261, >> aggrutil=0.01% >> sda: ios=1/2249, merge=7/559, ticks=9/254, in_queue=261, util=0.01% >> [root@rcprsdc1r72-01-ac rafaell]# >> >> Cheers, >> Raf >> >> >> -- >> Rafael Lopez >> Data Storage Administrator >> Servers & Storage (eSolutions) >> >> >> ________________________________________ >> >> PLEASE NOTE: The information contained in this electronic mail message is >> intended only for the use of the designated recipient(s) named above. If the >> reader of this message is not the intended recipient, you are hereby notified >> that you have received this message in error and that any review, >> dissemination, distribution, or copying of this message is strictly prohibited. If >> you have received this communication in error, please notify the sender by >> telephone or e-mail (as shown above) immediately and destroy any and all >> copies of this message in your possession (whether hard copies or >> electronically stored copies). >> >> >> >> >> -- >> Rafael Lopez >> Data Storage Administrator >> Servers & Storage (eSolutions) >> +61 3 990 59118 >> >> >> >> >> >> -- >> Rafael Lopez >> Data Storage Administrator >> Servers & Storage (eSolutions) >> +61 3 990 59118 > > > > > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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