Sorry for the delayed reply... I've been tracking some issues which cause high latency on our test machines, and it may be responsible for your problems as well. Could you retry those runs with the same debugging and 'journal dio' set to false?
Thanks for your patience, -Sam On Sat, Mar 24, 2012 at 12:09 PM, Andrey Korolyov <and...@xdel.ru> wrote: > http://xdel.ru/downloads/ceph-logs-dbg/ > > On Fri, Mar 23, 2012 at 9:53 PM, Samuel Just <sam.j...@dreamhost.com> wrote: >> (CCing the list) >> >> Actually, can you could re-do the rados bench run with 'debug journal >> = 20' along with the other debugging? That should give us better >> information. >> >> -Sam >> >> On Fri, Mar 23, 2012 at 5:25 AM, Andrey Korolyov <and...@xdel.ru> wrote: >>> Hi Sam, >>> >>> Can you please suggest on where to start profiling osd? If the >>> bottleneck has related to such non-complex things as directio speed, >>> I`m sure that I was able to catch it long ago, even crossing around by >>> results of other types of benchmarks at host system. I`ve just tried >>> tmpfs under both journals, it has a small boost effect, as expected >>> because of near-zero i/o delay. May be chunk distribution mechanism >>> does not work well on such small amount of nodes but right now I don`t >>> have necessary amount of hardware nodes to prove or disprove that. >>> >>> On Thu, Mar 22, 2012 at 10:40 PM, Andrey Korolyov <and...@xdel.ru> wrote: >>>> random-rw: (g=0): rw=write, bs=4K-4K/4K-4K, ioengine=sync, iodepth=2 >>>> Starting 1 process >>>> Jobs: 1 (f=1): [W] [100.0% done] [0K/35737K /s] [0/8725 iops] [eta 00m:00s] >>>> random-rw: (groupid=0, jobs=1): err= 0: pid=9647 >>>> write: io=163840KB, bw=37760KB/s, iops=9439, runt= 4339msec >>>> clat (usec): min=70, max=39801, avg=104.19, stdev=324.29 >>>> bw (KB/s) : min=30480, max=43312, per=98.83%, avg=37317.00, >>>> stdev=5770.28 >>>> cpu : usr=1.84%, sys=13.00%, ctx=40961, majf=0, minf=26 >>>> 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: total=0/40960, short=0/0 >>>> lat (usec): 100=79.69%, 250=19.89%, 500=0.12%, 750=0.12%, 1000=0.11% >>>> lat (msec): 2=0.01%, 4=0.01%, 10=0.03%, 20=0.01%, 50=0.01% >>>> >>>> >>>> On Thu, Mar 22, 2012 at 9:26 PM, Samuel Just <sam.j...@dreamhost.com> >>>> wrote: >>>>> Our journal writes are actually sequential. Could you send FIO >>>>> results for sequential 4k writes osd.0's journal and osd.1's journal? >>>>> -Sam >>>>> >>>>> On Thu, Mar 22, 2012 at 5:21 AM, Andrey Korolyov <and...@xdel.ru> wrote: >>>>>> FIO output for journal partition, directio enabled, seems good(same >>>>>> results for ext4 on other single sata disks). >>>>>> >>>>>> random-rw: (g=0): rw=randwrite, bs=4K-4K/4K-4K, ioengine=sync, iodepth=2 >>>>>> Starting 1 process >>>>>> Jobs: 1 (f=1): [w] [100.0% done] [0K/3219K /s] [0/786 iops] [eta 00m:00s] >>>>>> random-rw: (groupid=0, jobs=1): err= 0: pid=21926 >>>>>> write: io=163840KB, bw=2327KB/s, iops=581, runt= 70403msec >>>>>> clat (usec): min=122, max=441551, avg=1714.52, stdev=7565.04 >>>>>> bw (KB/s) : min= 552, max= 3880, per=100.61%, avg=2341.23, >>>>>> stdev=480.05 >>>>>> cpu : usr=0.42%, sys=1.34%, ctx=40976, majf=0, minf=42 >>>>>> 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: total=0/40960, short=0/0 >>>>>> lat (usec): 250=31.70%, 500=0.68%, 750=0.10%, 1000=0.63% >>>>>> lat (msec): 2=41.31%, 4=20.91%, 10=4.40%, 20=0.17%, 50=0.07% >>>>>> lat (msec): 500=0.04% >>>>>> >>>>>> >>>>>> >>>>>> On Thu, Mar 22, 2012 at 1:20 AM, Samuel Just <sam.j...@dreamhost.com> >>>>>> wrote: >>>>>>> (CCing the list) >>>>>>> >>>>>>> So, the problem isn't the bandwidth. Before we respond to the client, >>>>>>> we write the operation to the journal. In this case, that operation >>>>>>> is taking >1s per operation on osd.1. Both rbd and rados bench will >>>>>>> only allow a limited number of ops in flight at a time, so this >>>>>>> latency is killing your throughput. For comparison, the latency for >>>>>>> writing to the journal on osd.0 is < .3s. Can you measure direct io >>>>>>> latency for writes to your osd.1 journal file? >>>>>>> -Sam >>>>>>> >>>>>>> On Wed, Mar 21, 2012 at 1:56 PM, Andrey Korolyov <and...@xdel.ru> wrote: >>>>>>>> Oh, you may confuse with Zabbix metrics - y-axis means Megabytes/s, >>>>>>>> not Megabits. >>>>>>>> >>>>>>>> On Thu, Mar 22, 2012 at 12:53 AM, Andrey Korolyov <and...@xdel.ru> >>>>>>>> wrote: >>>>>>>>> [global] >>>>>>>>> log dir = /ceph/out >>>>>>>>> log_file = "" >>>>>>>>> logger dir = /ceph/log >>>>>>>>> pid file = /ceph/out/$type$id.pid >>>>>>>>> [mds] >>>>>>>>> pid file = /ceph/out/$name.pid >>>>>>>>> lockdep = 1 >>>>>>>>> mds log max segments = 2 >>>>>>>>> [osd] >>>>>>>>> lockdep = 1 >>>>>>>>> filestore_xattr_use_omap = 1 >>>>>>>>> osd data = /ceph/dev/osd$id >>>>>>>>> osd journal = /ceph/meta/journal >>>>>>>>> osd journal size = 100 >>>>>>>>> [mon] >>>>>>>>> lockdep = 1 >>>>>>>>> mon data = /ceph/dev/mon$id >>>>>>>>> [mon.0] >>>>>>>>> host = 172.20.1.32 >>>>>>>>> mon addr = 172.20.1.32:6789 >>>>>>>>> [mon.1] >>>>>>>>> host = 172.20.1.33 >>>>>>>>> mon addr = 172.20.1.33:6789 >>>>>>>>> [mon.2] >>>>>>>>> host = 172.20.1.35 >>>>>>>>> mon addr = 172.20.1.35:6789 >>>>>>>>> [osd.0] >>>>>>>>> host = 172.20.1.32 >>>>>>>>> [osd.1] >>>>>>>>> host = 172.20.1.33 >>>>>>>>> [mds.a] >>>>>>>>> host = 172.20.1.32 >>>>>>>>> >>>>>>>>> /dev/sda1 on /ceph type ext4 (rw,barrier=0,user_xattr) >>>>>>>>> /dev/mapper/system-cephmeta on /ceph/meta type ext4 >>>>>>>>> (rw,barrier=0,user_xattr) >>>>>>>>> Simple performance tests on those fs shows ~133Mb/s for /ceph and >>>>>>>>> metadata/. Also both machines do not hold anything else which may >>>>>>>>> impact osd. >>>>>>>>> >>>>>>>>> Also please note of following: >>>>>>>>> >>>>>>>>> http://i.imgur.com/ZgFdO.png >>>>>>>>> >>>>>>>>> First two peaks are related to running rados bench, then goes cluster >>>>>>>>> recreation, automated debian install and final peaks are dd test. >>>>>>>>> Surely I can have more precise graphs, but current one probably enough >>>>>>>>> to state a situation - rbd utilizing about a quarter of possible >>>>>>>>> bandwidth(if we can count rados bench as 100%). >>>>>>>>> >>>>>>>>> On Thu, Mar 22, 2012 at 12:39 AM, Samuel Just >>>>>>>>> <sam.j...@dreamhost.com> wrote: >>>>>>>>>> Hmm, there seem to be writes taking as long as 1.5s to hit journal on >>>>>>>>>> osd.1... Could you post your ceph.conf? Might there be a problem >>>>>>>>>> with the osd.1 journal disk? >>>>>>>>>> -Sam >>>>>>>>>> >>>>>>>>>> On Wed, Mar 21, 2012 at 1:25 PM, Andrey Korolyov <and...@xdel.ru> >>>>>>>>>> wrote: >>>>>>>>>>> Oh, sorry - they probably inherited rights from log files, fixed. >>>>>>>>>>> >>>>>>>>>>> On Thu, Mar 22, 2012 at 12:17 AM, Samuel Just >>>>>>>>>>> <sam.j...@dreamhost.com> wrote: >>>>>>>>>>>> I get 403 Forbidden when I try to download any of the files. >>>>>>>>>>>> -Sam >>>>>>>>>>>> >>>>>>>>>>>> On Wed, Mar 21, 2012 at 11:51 AM, Andrey Korolyov <and...@xdel.ru> >>>>>>>>>>>> wrote: >>>>>>>>>>>>> http://xdel.ru/downloads/ceph-logs/ >>>>>>>>>>>>> >>>>>>>>>>>>> 1/ contains logs related to bench initiated at the osd0 machine >>>>>>>>>>>>> and 2/ >>>>>>>>>>>>> - at osd1. >>>>>>>>>>>>> >>>>>>>>>>>>> On Wed, Mar 21, 2012 at 8:54 PM, Samuel Just >>>>>>>>>>>>> <sam.j...@dreamhost.com> wrote: >>>>>>>>>>>>>> Hmm, I'm seeing some very high latency on ops sent to osd.1. >>>>>>>>>>>>>> Can you >>>>>>>>>>>>>> post osd.1's logs? >>>>>>>>>>>>>> -Sam >>>>>>>>>>>>>> >>>>>>>>>>>>>> On Wed, Mar 21, 2012 at 3:51 AM, Andrey Korolyov >>>>>>>>>>>>>> <and...@xdel.ru> wrote: >>>>>>>>>>>>>>> Here, please: http://xdel.ru/downloads/ceph.log.gz >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Sometimes 'cur MB/s ' shows zero during rados bench, even if >>>>>>>>>>>>>>> any debug >>>>>>>>>>>>>>> output disabled and log_file set to the empty value, hope it`s >>>>>>>>>>>>>>> okay. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> On Wed, Mar 21, 2012 at 2:36 AM, Samuel Just >>>>>>>>>>>>>>> <sam.j...@dreamhost.com> wrote: >>>>>>>>>>>>>>>> Can you set osd and filestore debugging to 20, restart the >>>>>>>>>>>>>>>> osds, run >>>>>>>>>>>>>>>> rados bench as before, and post the logs? >>>>>>>>>>>>>>>> -Sam Just >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> On Tue, Mar 20, 2012 at 1:37 PM, Andrey Korolyov >>>>>>>>>>>>>>>> <and...@xdel.ru> wrote: >>>>>>>>>>>>>>>>> rados bench 60 write -p data >>>>>>>>>>>>>>>>> <skip> >>>>>>>>>>>>>>>>> Total time run: 61.217676 >>>>>>>>>>>>>>>>> Total writes made: 989 >>>>>>>>>>>>>>>>> Write size: 4194304 >>>>>>>>>>>>>>>>> Bandwidth (MB/sec): 64.622 >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Average Latency: 0.989608 >>>>>>>>>>>>>>>>> Max latency: 2.21701 >>>>>>>>>>>>>>>>> Min latency: 0.255315 >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Here a snip from osd log, seems write size is okay. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> 2012-03-21 00:00:39.397066 7fdda86a7700 osd.0 10 pg[0.58( v >>>>>>>>>>>>>>>>> 10'83 >>>>>>>>>>>>>>>>> (0'0,10'83] n=50 ec=1 les/c 9/9 8/8/6) [0,1] r=0 lpr=8 mlcod >>>>>>>>>>>>>>>>> 10'82 >>>>>>>>>>>>>>>>> active+clean] removing repgather(0x31b5360 applying 10'83 >>>>>>>>>>>>>>>>> rep_tid=597 >>>>>>>>>>>>>>>>> wfack= wfdisk= op=osd_op(client.4599.0:2533 >>>>>>>>>>>>>>>>> rb.0.2.000000000040 [write >>>>>>>>>>>>>>>>> 1220608~4096] 0.17eb9fd8) v4) >>>>>>>>>>>>>>>>> 2012-03-21 00:00:39.397086 7fdda86a7700 osd.0 10 pg[0.58( v >>>>>>>>>>>>>>>>> 10'83 >>>>>>>>>>>>>>>>> (0'0,10'83] n=50 ec=1 les/c 9/9 8/8/6) [0,1] r=0 lpr=8 mlcod >>>>>>>>>>>>>>>>> 10'82 >>>>>>>>>>>>>>>>> active+clean] q front is repgather(0x31b5360 applying 10'83 >>>>>>>>>>>>>>>>> rep_tid=597 wfack= wfdisk= op=osd_op(client.4599.0:2533 >>>>>>>>>>>>>>>>> rb.0.2.000000000040 [write 1220608~4096] 0.17eb9fd8) v4) >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Sorry for my previous question about rbd chunks, it was >>>>>>>>>>>>>>>>> really stupid :) >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> On Mon, Mar 19, 2012 at 10:40 PM, Josh Durgin >>>>>>>>>>>>>>>>> <josh.dur...@dreamhost.com> wrote: >>>>>>>>>>>>>>>>>> On 03/19/2012 11:13 AM, Andrey Korolyov wrote: >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> Nope, I`m using KVM for rbd guests. Surely I`ve been >>>>>>>>>>>>>>>>>>> noticed that Sage >>>>>>>>>>>>>>>>>>> mentioned too small value and I`ve changed it to 64M before >>>>>>>>>>>>>>>>>>> posting >>>>>>>>>>>>>>>>>>> previous message with no success - both 8M and this value >>>>>>>>>>>>>>>>>>> cause a >>>>>>>>>>>>>>>>>>> performance drop. When I tried to wrote small amount of >>>>>>>>>>>>>>>>>>> data that can >>>>>>>>>>>>>>>>>>> be compared to writeback cache size(both on raw device and >>>>>>>>>>>>>>>>>>> ext3 with >>>>>>>>>>>>>>>>>>> sync option), following results were made: >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> I just want to clarify that the writeback window isn't a >>>>>>>>>>>>>>>>>> full writeback >>>>>>>>>>>>>>>>>> cache - it doesn't affect reads, and does not help with >>>>>>>>>>>>>>>>>> request merging etc. >>>>>>>>>>>>>>>>>> It simply allows a bunch of writes to be in flight while >>>>>>>>>>>>>>>>>> acking the write to >>>>>>>>>>>>>>>>>> the guest immediately. We're working on a full-fledged >>>>>>>>>>>>>>>>>> writeback cache that >>>>>>>>>>>>>>>>>> to replace the writeback window. >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> dd if=/dev/zero of=/var/img.1 bs=10M count=10 oflag=direct >>>>>>>>>>>>>>>>>>> (almost >>>>>>>>>>>>>>>>>>> same without oflag there and in the following samples) >>>>>>>>>>>>>>>>>>> 10+0 records in >>>>>>>>>>>>>>>>>>> 10+0 records out >>>>>>>>>>>>>>>>>>> 104857600 bytes (105 MB) copied, 0.864404 s, 121 MB/s >>>>>>>>>>>>>>>>>>> dd if=/dev/zero of=/var/img.1 bs=10M count=20 oflag=direct >>>>>>>>>>>>>>>>>>> 20+0 records in >>>>>>>>>>>>>>>>>>> 20+0 records out >>>>>>>>>>>>>>>>>>> 209715200 bytes (210 MB) copied, 6.67271 s, 31.4 MB/s >>>>>>>>>>>>>>>>>>> dd if=/dev/zero of=/var/img.1 bs=10M count=30 oflag=direct >>>>>>>>>>>>>>>>>>> 30+0 records in >>>>>>>>>>>>>>>>>>> 30+0 records out >>>>>>>>>>>>>>>>>>> 314572800 bytes (315 MB) copied, 12.4806 s, 25.2 MB/s >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> and so on. Reference test with bs=1M and count=2000 has >>>>>>>>>>>>>>>>>>> slightly worse >>>>>>>>>>>>>>>>>>> results _with_ writeback cache than without, as I`ve >>>>>>>>>>>>>>>>>>> mentioned before. >>>>>>>>>>>>>>>>>>> Here the bench results, they`re almost equal on both nodes: >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> bench: wrote 1024 MB in blocks of 4096 KB in 9.037468 sec >>>>>>>>>>>>>>>>>>> at 113 MB/sec >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> One thing to check is the size of the writes that are >>>>>>>>>>>>>>>>>> actually being sent by >>>>>>>>>>>>>>>>>> rbd. The guest is probably splitting them into relatively >>>>>>>>>>>>>>>>>> small (128 or >>>>>>>>>>>>>>>>>> 256k) writes. Ideally it would be sending 4k writes, and >>>>>>>>>>>>>>>>>> this should be a >>>>>>>>>>>>>>>>>> lot faster. >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> You can see the writes being sent by adding debug_ms=1 to >>>>>>>>>>>>>>>>>> the client or osd. >>>>>>>>>>>>>>>>>> The format is osd_op(.*[write OFFSET~LENGTH]). >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> Also, because I`ve not mentioned it before, network >>>>>>>>>>>>>>>>>>> performance is >>>>>>>>>>>>>>>>>>> enough to hold fair gigabit connectivity with MTU 1500. >>>>>>>>>>>>>>>>>>> Seems that it >>>>>>>>>>>>>>>>>>> is not interrupt problem or something like it - even if >>>>>>>>>>>>>>>>>>> ceph-osd, >>>>>>>>>>>>>>>>>>> ethernet card queues and kvm instance pinned to different >>>>>>>>>>>>>>>>>>> sets of >>>>>>>>>>>>>>>>>>> cores, nothing changes. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> On Mon, Mar 19, 2012 at 8:59 PM, Greg Farnum >>>>>>>>>>>>>>>>>>> <gregory.far...@dreamhost.com> wrote: >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> It sounds like maybe you're using Xen? The "rbd writeback >>>>>>>>>>>>>>>>>>>> window" option >>>>>>>>>>>>>>>>>>>> only works for userspace rbd implementations (eg, KVM). >>>>>>>>>>>>>>>>>>>> If you are using KVM, you probably want 81920000 (~80MB) >>>>>>>>>>>>>>>>>>>> rather than >>>>>>>>>>>>>>>>>>>> 8192000 (~8MB). >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> What options are you running dd with? If you run a rados >>>>>>>>>>>>>>>>>>>> bench from both >>>>>>>>>>>>>>>>>>>> machines, what do the results look like? >>>>>>>>>>>>>>>>>>>> Also, can you do the ceph osd bench on each of your OSDs, >>>>>>>>>>>>>>>>>>>> please? >>>>>>>>>>>>>>>>>>>> (http://ceph.newdream.net/wiki/Troubleshooting#OSD_performance) >>>>>>>>>>>>>>>>>>>> -Greg >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> On Monday, March 19, 2012 at 6:46 AM, Andrey Korolyov >>>>>>>>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> More strangely, writing speed drops down by fifteen >>>>>>>>>>>>>>>>>>>>> percent when this >>>>>>>>>>>>>>>>>>>>> option was set in vm` config(instead of result from >>>>>>>>>>>>>>>>>>>>> http://www.mail-archive.com/ceph-devel@vger.kernel.org/msg03685.html). >>>>>>>>>>>>>>>>>>>>> As I mentioned, I`m using 0.43, but due to crashed osds, >>>>>>>>>>>>>>>>>>>>> ceph has been >>>>>>>>>>>>>>>>>>>>> recompiled with e43546dee9246773ffd6877b4f9495f1ec61cd55 >>>>>>>>>>>>>>>>>>>>> and >>>>>>>>>>>>>>>>>>>>> 1468d95101adfad44247016a1399aab6b86708d2 - both cases >>>>>>>>>>>>>>>>>>>>> caused crashes >>>>>>>>>>>>>>>>>>>>> under heavy load. >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> On Sun, Mar 18, 2012 at 10:22 PM, Sage >>>>>>>>>>>>>>>>>>>>> Weil<s...@newdream.net >>>>>>>>>>>>>>>>>>>>> (mailto:s...@newdream.net)> wrote: >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> On Sat, 17 Mar 2012, Andrey Korolyov wrote: >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> Hi, >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> I`ve did some performance tests at the following >>>>>>>>>>>>>>>>>>>>>>> configuration: >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> mon0, osd0 and mon1, osd1 - two twelve-core r410 with >>>>>>>>>>>>>>>>>>>>>>> 32G ram, mon2 - >>>>>>>>>>>>>>>>>>>>>>> dom0 with three dedicated cores and 1.5G, mostly idle. >>>>>>>>>>>>>>>>>>>>>>> First three >>>>>>>>>>>>>>>>>>>>>>> disks on each r410 arranged into raid0 and holds osd >>>>>>>>>>>>>>>>>>>>>>> data when fourth >>>>>>>>>>>>>>>>>>>>>>> holds os and osd` journal partition, all ceph-related >>>>>>>>>>>>>>>>>>>>>>> stuff mounted on >>>>>>>>>>>>>>>>>>>>>>> the ext4 without barriers. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> Firstly, I`ve noticed about a difference of benchmark >>>>>>>>>>>>>>>>>>>>>>> performance and >>>>>>>>>>>>>>>>>>>>>>> write speed through rbd from small kvm instance running >>>>>>>>>>>>>>>>>>>>>>> on one of >>>>>>>>>>>>>>>>>>>>>>> first two machines - when bench gave me about 110Mb/s, >>>>>>>>>>>>>>>>>>>>>>> writing zeros >>>>>>>>>>>>>>>>>>>>>>> to raw block device inside vm with dd was at top speed >>>>>>>>>>>>>>>>>>>>>>> about 45 mb/s, >>>>>>>>>>>>>>>>>>>>>>> for vm`fs (ext4 with default options) performance drops >>>>>>>>>>>>>>>>>>>>>>> to ~23Mb/s. >>>>>>>>>>>>>>>>>>>>>>> Things get worse, when I`ve started second vm at second >>>>>>>>>>>>>>>>>>>>>>> host and tried >>>>>>>>>>>>>>>>>>>>>>> to continue same dd tests simultaneously - performance >>>>>>>>>>>>>>>>>>>>>>> fairly divided >>>>>>>>>>>>>>>>>>>>>>> by half for each instance :). Enabling jumbo frames, >>>>>>>>>>>>>>>>>>>>>>> playing with cpu >>>>>>>>>>>>>>>>>>>>>>> affinity for ceph and vm instances and trying different >>>>>>>>>>>>>>>>>>>>>>> TCP congestion >>>>>>>>>>>>>>>>>>>>>>> protocols gave no effect at all - with DCTCP I have >>>>>>>>>>>>>>>>>>>>>>> slightly smoother >>>>>>>>>>>>>>>>>>>>>>> network load graph and that`s all. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> Can ml please suggest anything to try to improve >>>>>>>>>>>>>>>>>>>>>>> performance? >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> Can you try setting >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> rbd writeback window = 8192000 >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> or similar, and see what kind of effect that has? I >>>>>>>>>>>>>>>>>>>>>> suspect it'll speed >>>>>>>>>>>>>>>>>>>>>> up dd; I'm less sure about ext3. >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> Thanks! >>>>>>>>>>>>>>>>>>>>>> sage >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> ceph-0.43, libvirt-0.9.8, qemu-1.0.0, kernel 3.2 >>>>>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>>>>>> To unsubscribe from this list: send the line >>>>>>>>>>>>>>>>>>>>>>> "unsubscribe ceph-devel" >>>>>>>>>>>>>>>>>>>>>>> in >>>>>>>>>>>>>>>>>>>>>>> the body of a message to majord...@vger.kernel.org >>>>>>>>>>>>>>>>>>>>>>> (mailto:majord...@vger.kernel.org) >>>>>>>>>>>>>>>>>>>>>>> More majordomo info at >>>>>>>>>>>>>>>>>>>>>>> http://vger.kernel.org/majordomo-info.html >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>>>> To unsubscribe from this list: send the line "unsubscribe >>>>>>>>>>>>>>>>>>>>> ceph-devel" in >>>>>>>>>>>>>>>>>>>>> the body of a message to majord...@vger.kernel.org >>>>>>>>>>>>>>>>>>>>> (mailto:majord...@vger.kernel.org) >>>>>>>>>>>>>>>>>>>>> More majordomo info at >>>>>>>>>>>>>>>>>>>>> http://vger.kernel.org/majordomo-info.html >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>>>> To unsubscribe from this list: send the line "unsubscribe >>>>>>>>>>>>>>>>>>> ceph-devel" in >>>>>>>>>>>>>>>>>>> the body of a message to majord...@vger.kernel.org >>>>>>>>>>>>>>>>>>> More majordomo info at >>>>>>>>>>>>>>>>>>> http://vger.kernel.org/majordomo-info.html >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>>> To unsubscribe from this list: send the line "unsubscribe >>>>>>>>>>>>>>>>> ceph-devel" in >>>>>>>>>>>>>>>>> the body of a message to majord...@vger.kernel.org >>>>>>>>>>>>>>>>> More majordomo info at >>>>>>>>>>>>>>>>> http://vger.kernel.org/majordomo-info.html >>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>>> To unsubscribe from this list: send the line "unsubscribe >>>>>>>>>>>>>>>> ceph-devel" in >>>>>>>>>>>>>>>> the body of a message to majord...@vger.kernel.org >>>>>>>>>>>>>>>> More majordomo info at >>>>>>>>>>>>>>>> http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html