On 08/29/2014 06:10 AM, Dan Van Der Ster wrote: > Hi Sebastien, > Here?s my recipe for max IOPS on a _testing_ instance with SSDs: > > osd op threads = 2 With SSDs, In the past I've seen increasing the osd op thread count can help random reads. > osd disk threads = 2 > journal max write bytes = 10485760000 > journal queue max bytes = 10485760000 > journal max write entries = 10000 > journal queue max ops = 50000 > filestore op threads = 2 > filestore max sync interval = 60 > filestore queue max ops = 50000 > filestore queue max bytes = 10485760000 > filestore queue committing max bytes = 10485760000 > filestore queue committing max ops = 50000 > filestore wbthrottle xfs bytes start flusher = 4194304000 > filestore wbthrottle xfs bytes hard limit = 41943040000 > filestore wbthrottle xfs ios start flusher = 50000 > filestore wbthrottle xfs ios hard limit = 500000 > filestore wbthrottle xfs inodes start flusher = 50000 > filestore wbthrottle xfs inodes hard limit = 500000 It's also probably worth trying disabling all in-memory logging. Unfortunately I don't think we have a global flag to do this, so you have to do it on a per-log basis which is annoying. > > Basically the goal there is to ensure no IOs are blocked from entering any queue. (And don?t run that in production!) > IIRC I can get up to around 5000 IOPS to a single fio/rbd client. Related to the sync interval, I was also playing with vm.dirty_expire_centisecs and vm.dirty_writeback_centisecs to disable the background page flushing (disables FileStore flushing). That way, the only disk activity becomes the journal writes. You can confirm that with iostat. > > Another thing that comes to mind is at some point a single fio/librbd client will be the bottleneck. Did you try running two simultaneous fio?s (then adding the results)? > > Cheers, Dan > > -- Dan van der Ster || Data & Storage Services || CERN IT Department -- > > > On 28 Aug 2014, at 18:11, Sebastien Han <sebastien.han at enovance.com> wrote: > >> Hey all, >> >> It has been a while since the last thread performance related on the ML :p >> I?ve been running some experiment to see how much I can get from an SSD on a Ceph cluster. >> To achieve that I did something pretty simple: >> >> * Debian wheezy 7.6 >> * kernel from debian 3.14-0.bpo.2-amd64 >> * 1 cluster, 3 mons (i?d like to keep this realistic since in a real deployment i?ll use 3) >> * 1 OSD backed by an SSD (journal and osd data on the same device) >> * 1 replica count of 1 >> * partitions are perfectly aligned >> * io scheduler is set to noon but deadline was showing the same results >> * no updatedb running >> >> About the box: >> >> * 32GB of RAM >> * 12 cores with HT @ 2,4 GHz >> * WB cache is enabled on the controller >> * 10Gbps network (doesn?t help here) >> >> The SSD is a 200G Intel DC S3700 and is capable of delivering around 29K iops with random 4k writes (my fio results) >> As a benchmark tool I used fio with the rbd engine (thanks deutsche telekom guys!). >> >> O_DIECT and D_SYNC don?t seem to be a problem for the SSD: >> >> # dd if=/dev/urandom of=rand.file bs=4k count=65536 >> 65536+0 records in >> 65536+0 records out >> 268435456 bytes (268 MB) copied, 29.5477 s, 9.1 MB/s >> >> # du -sh rand.file >> 256M rand.file >> >> # dd if=rand.file of=/dev/sdo bs=4k count=65536 oflag=dsync,direct >> 65536+0 records in >> 65536+0 records out >> 268435456 bytes (268 MB) copied, 2.73628 s, 98.1 MB/s >> >> See my ceph.conf: >> >> [global] >> auth cluster required = cephx >> auth service required = cephx >> auth client required = cephx >> fsid = 857b8609-8c9b-499e-9161-2ea67ba51c97 >> osd pool default pg num = 4096 >> osd pool default pgp num = 4096 >> osd pool default size = 2 >> osd crush chooseleaf type = 0 >> >> debug lockdep = 0/0 >> debug context = 0/0 >> debug crush = 0/0 >> debug buffer = 0/0 >> debug timer = 0/0 >> debug journaler = 0/0 >> debug osd = 0/0 >> debug optracker = 0/0 >> debug objclass = 0/0 >> debug filestore = 0/0 >> debug journal = 0/0 >> debug ms = 0/0 >> debug monc = 0/0 >> debug tp = 0/0 >> debug auth = 0/0 >> debug finisher = 0/0 >> debug heartbeatmap = 0/0 >> debug perfcounter = 0/0 >> debug asok = 0/0 >> debug throttle = 0/0 >> >> [mon] >> mon osd down out interval = 600 >> mon osd min down reporters = 13 >> [mon.ceph-01] >> host = ceph-01 >> mon addr = 172.20.20.171 >> [mon.ceph-02] >> host = ceph-02 >> mon addr = 172.20.20.172 >> [mon.ceph-03] >> host = ceph-03 >> mon addr = 172.20.20.173 >> >> debug lockdep = 0/0 >> debug context = 0/0 >> debug crush = 0/0 >> debug buffer = 0/0 >> debug timer = 0/0 >> debug journaler = 0/0 >> debug osd = 0/0 >> debug optracker = 0/0 >> debug objclass = 0/0 >> debug filestore = 0/0 >> debug journal = 0/0 >> debug ms = 0/0 >> debug monc = 0/0 >> debug tp = 0/0 >> debug auth = 0/0 >> debug finisher = 0/0 >> debug heartbeatmap = 0/0 >> debug perfcounter = 0/0 >> debug asok = 0/0 >> debug throttle = 0/0 >> >> [osd] >> osd mkfs type = xfs >> osd mkfs options xfs = -f -i size=2048 >> osd mount options xfs = rw,noatime,logbsize=256k,delaylog >> osd journal size = 20480 >> cluster_network = 172.20.20.0/24 >> public_network = 172.20.20.0/24 >> osd mon heartbeat interval = 30 >> # Performance tuning >> filestore merge threshold = 40 >> filestore split multiple = 8 >> osd op threads = 8 >> # Recovery tuning >> osd recovery max active = 1 >> osd max backfills = 1 >> osd recovery op priority = 1 >> >> >> debug lockdep = 0/0 >> debug context = 0/0 >> debug crush = 0/0 >> debug buffer = 0/0 >> debug timer = 0/0 >> debug journaler = 0/0 >> debug osd = 0/0 >> debug optracker = 0/0 >> debug objclass = 0/0 >> debug filestore = 0/0 >> debug journal = 0/0 >> debug ms = 0/0 >> debug monc = 0/0 >> debug tp = 0/0 >> debug auth = 0/0 >> debug finisher = 0/0 >> debug heartbeatmap = 0/0 >> debug perfcounter = 0/0 >> debug asok = 0/0 >> debug throttle = 0/0 >> >> Disabling all debugging made me win 200/300 more IOPS. >> >> See my fio template: >> >> [global] >> #logging >> #write_iops_log=write_iops_log >> #write_bw_log=write_bw_log >> #write_lat_log=write_lat_lo >> >> time_based >> runtime=60 >> >> ioengine=rbd >> clientname=admin >> pool=test >> rbdname=fio >> invalidate=0 # mandatory >> #rw=randwrite >> rw=write >> bs=4k >> #bs=32m >> size=5G >> group_reporting >> >> [rbd_iodepth32] >> iodepth=32 >> direct=1 >> >> See my rio output: >> >> rbd_iodepth32: (g=0): rw=write, bs=4K-4K/4K-4K/4K-4K, ioengine=rbd, iodepth=32 >> fio-2.1.11-14-gb74e >> Starting 1 process >> rbd engine: RBD version: 0.1.8 >> Jobs: 1 (f=1): [W(1)] [100.0% done] [0KB/12876KB/0KB /s] [0/3219/0 iops] [eta 00m:00s] >> rbd_iodepth32: (groupid=0, jobs=1): err= 0: pid=32116: Thu Aug 28 00:28:26 2014 >> write: io=771448KB, bw=12855KB/s, iops=3213, runt= 60010msec >> slat (usec): min=42, max=1578, avg=66.50, stdev=16.96 >> clat (msec): min=1, max=28, avg= 9.85, stdev= 1.48 >> lat (msec): min=1, max=28, avg= 9.92, stdev= 1.47 >> clat percentiles (usec): >> | 1.00th=[ 6368], 5.00th=[ 8256], 10.00th=[ 8640], 20.00th=[ 9152], >> | 30.00th=[ 9408], 40.00th=[ 9664], 50.00th=[ 9792], 60.00th=[10048], >> | 70.00th=[10176], 80.00th=[10560], 90.00th=[10944], 95.00th=[11456], >> | 99.00th=[13120], 99.50th=[16768], 99.90th=[25984], 99.95th=[27008], >> | 99.99th=[28032] >> bw (KB /s): min=11864, max=13808, per=100.00%, avg=12864.36, stdev=407.35 >> lat (msec) : 2=0.03%, 4=0.54%, 10=59.79%, 20=39.24%, 50=0.41% >> cpu : usr=19.15%, sys=4.69%, ctx=326309, majf=0, minf=426088 >> IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=33.9%, 32=66.1%, >=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=99.6%, 8=0.4%, 16=0.1%, 32=0.1%, 64=0.0%, >=64=0.0% >> issued : total=r=0/w=192862/d=0, short=r=0/w=0/d=0 >> latency : target=0, window=0, percentile=100.00%, depth=32 >> >> Run status group 0 (all jobs): >> WRITE: io=771448KB, aggrb=12855KB/s, minb=12855KB/s, maxb=12855KB/s, mint=60010msec, maxt=60010msec >> >> Disk stats (read/write): >> dm-1: ios=0/49, merge=0/0, ticks=0/12, in_queue=12, util=0.01%, aggrios=0/22, aggrmerge=0/27, aggrticks=0/12, aggrin_queue=12, aggrutil=0.01% >> sda: ios=0/22, merge=0/27, ticks=0/12, in_queue=12, util=0.01% >> >> I tried to tweak several parameters like: >> >> filestore_wbthrottle_xfs_ios_start_flusher = 10000 >> filestore_wbthrottle_xfs_ios_hard_limit = 10000 >> filestore_wbthrottle_btrfs_ios_start_flusher = 10000 >> filestore_wbthrottle_btrfs_ios_hard_limit = 10000 >> filestore queue max ops = 2000 >> >> But didn?t any improvement. >> >> Then I tried other things: >> >> * Increasing the io_depth up to 256 or 512 gave me between 50 to 100 more IOPS but it?s not a realistic workload anymore and not that significant. >> * adding another SSD for the journal, still getting 3,2K IOPS >> * I tried with rbd bench and I also got 3K IOPS >> * I ran the test on a client machine and then locally on the server, still getting 3,2K IOPS >> * put the journal in memory, still getting 3,2K IOPS >> * with 2 clients running the test in parallel I got a total of 3,6K IOPS but I don?t seem to be able to go over >> * I tried is to add another OSD to that SSD, so I had 2 OSD and 2 journals on 1 SSD, got 4,5K IOPS YAY! >> >> Given the results of the last time it seems that something is limiting the number of IOPS per OSD process. >> >> Running the test on a client or locally didn?t show any difference. >> So it looks to me that there is some contention within Ceph that might cause this. >> >> I also ran perf and looked at the output, everything looks decent, but someone might want to have a look at it :). >> >> We have been able to reproduce this on 3 distinct platforms with some deviations (because of the hardware) but the behaviour is the same. >> Any thoughts will be highly appreciated, only getting 3,2k out of an 29K IOPS SSD is a bit frustrating :). >> >> Cheers. >> ???? >> S?bastien Han >> Cloud Architect >> >> "Always give 100%. Unless you're giving blood." >> >> Phone: +33 (0)1 49 70 99 72 >> Mail: sebastien.han at enovance.com >> Address : 11 bis, rue Roqu?pine - 75008 Paris >> Web : www.enovance.com - Twitter : @enovance >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users at lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > _______________________________________________ > ceph-users mailing list > ceph-users at lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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