On Tue, 22 Sep 2015, Samuel Just wrote: > I looked at the logs, it looks like there was a 53 second delay > between when osd.17 started sending the osd_repop message and when > osd.13 started reading it, which is pretty weird. Sage, didn't we > once see a kernel issue which caused some messages to be mysteriously > delayed for many 10s of seconds?
Every time we have seen this behavior and diagnosed it in the wild it has been a network misconfiguration. Usually related to jumbo frames. sage > > What kernel are you running? > -Sam > > On Tue, Sep 22, 2015 at 2:22 PM, Robert LeBlanc <rob...@leblancnet.us> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA256 > > > > OK, looping in ceph-devel to see if I can get some more eyes. I've > > extracted what I think are important entries from the logs for the > > first blocked request. NTP is running all the servers so the logs > > should be close in terms of time. Logs for 12:50 to 13:00 are > > available at http://162.144.87.113/files/ceph_block_io.logs.tar.xz > > > > 2015-09-22 12:55:06.500374 - osd.17 gets I/O from client > > 2015-09-22 12:55:06.557160 - osd.17 submits I/O to osd.13 > > 2015-09-22 12:55:06.557305 - osd.17 submits I/O to osd.16 > > 2015-09-22 12:55:06.573711 - osd.16 gets I/O from osd.17 > > 2015-09-22 12:55:06.595716 - osd.17 gets ondisk result=0 from osd.16 > > 2015-09-22 12:55:06.640631 - osd.16 reports to osd.17 ondisk result=0 > > 2015-09-22 12:55:36.926691 - osd.17 reports slow I/O > 30.439150 sec > > 2015-09-22 12:55:59.790591 - osd.13 gets I/O from osd.17 > > 2015-09-22 12:55:59.812405 - osd.17 gets ondisk result=0 from osd.13 > > 2015-09-22 12:56:02.941602 - osd.13 reports to osd.17 ondisk result=0 > > > > In the logs I can see that osd.17 dispatches the I/O to osd.13 and > > osd.16 almost silmutaniously. osd.16 seems to get the I/O right away, > > but for some reason osd.13 doesn't get the message until 53 seconds > > later. osd.17 seems happy to just wait and doesn't resend the data > > (well, I'm not 100% sure how to tell which entries are the actual data > > transfer). > > > > It looks like osd.17 is receiving responses to start the communication > > with osd.13, but the op is not acknowledged until almost a minute > > later. To me it seems that the message is getting received but not > > passed to another thread right away or something. This test was done > > with an idle cluster, a single fio client (rbd engine) with a single > > thread. > > > > The OSD servers are almost 100% idle during these blocked I/O > > requests. I think I'm at the end of my troubleshooting, so I can use > > some help. > > > > Single Test started about > > 2015-09-22 12:52:36 > > > > 2015-09-22 12:55:36.926680 osd.17 192.168.55.14:6800/16726 56 : > > cluster [WRN] 1 slow requests, 1 included below; oldest blocked for > > > 30.439150 secs > > 2015-09-22 12:55:36.926699 osd.17 192.168.55.14:6800/16726 57 : > > cluster [WRN] slow request 30.439150 seconds old, received at > > 2015-09-22 12:55:06.487451: > > osd_op(client.250874.0:1388 rbd_data.3380e2ae8944a.0000000000000545 > > [set-alloc-hint object_size 4194304 write_size 4194304,write > > 0~4194304] 8.bbf3e8ff ack+ondisk+write+known_if_redirected e56785) > > currently waiting for subops from 13,16 > > 2015-09-22 12:55:36.697904 osd.16 192.168.55.13:6800/29410 7 : cluster > > [WRN] 2 slow requests, 2 included below; oldest blocked for > > > 30.379680 secs > > 2015-09-22 12:55:36.697918 osd.16 192.168.55.13:6800/29410 8 : cluster > > [WRN] slow request 30.291520 seconds old, received at 2015-09-22 > > 12:55:06.406303: > > osd_op(client.250874.0:1384 rbd_data.3380e2ae8944a.0000000000000541 > > [set-alloc-hint object_size 4194304 write_size 4194304,write > > 0~4194304] 8.5fb2123f ack+ondisk+write+known_if_redirected e56785) > > currently waiting for subops from 13,17 > > 2015-09-22 12:55:36.697927 osd.16 192.168.55.13:6800/29410 9 : cluster > > [WRN] slow request 30.379680 seconds old, received at 2015-09-22 > > 12:55:06.318144: > > osd_op(client.250874.0:1382 rbd_data.3380e2ae8944a.000000000000053f > > [set-alloc-hint object_size 4194304 write_size 4194304,write > > 0~4194304] 8.312e69ca ack+ondisk+write+known_if_redirected e56785) > > currently waiting for subops from 13,14 > > 2015-09-22 12:58:03.998275 osd.13 192.168.55.12:6804/4574 130 : > > cluster [WRN] 1 slow requests, 1 included below; oldest blocked for > > > 30.954212 secs > > 2015-09-22 12:58:03.998286 osd.13 192.168.55.12:6804/4574 131 : > > cluster [WRN] slow request 30.954212 seconds old, received at > > 2015-09-22 12:57:33.044003: > > osd_op(client.250874.0:1873 rbd_data.3380e2ae8944a.000000000000070d > > [set-alloc-hint object_size 4194304 write_size 4194304,write > > 0~4194304] 8.e69870d4 ack+ondisk+write+known_if_redirected e56785) > > currently waiting for subops from 16,17 > > 2015-09-22 12:58:03.759826 osd.16 192.168.55.13:6800/29410 10 : > > cluster [WRN] 1 slow requests, 1 included below; oldest blocked for > > > 30.704367 secs > > 2015-09-22 12:58:03.759840 osd.16 192.168.55.13:6800/29410 11 : > > cluster [WRN] slow request 30.704367 seconds old, received at > > 2015-09-22 12:57:33.055404: > > osd_op(client.250874.0:1874 rbd_data.3380e2ae8944a.000000000000070e > > [set-alloc-hint object_size 4194304 write_size 4194304,write > > 0~4194304] 8.f7635819 ack+ondisk+write+known_if_redirected e56785) > > currently waiting for subops from 13,17 > > > > Server IP addr OSD > > nodev - 192.168.55.11 - 12 > > nodew - 192.168.55.12 - 13 > > nodex - 192.168.55.13 - 16 > > nodey - 192.168.55.14 - 17 > > nodez - 192.168.55.15 - 14 > > nodezz - 192.168.55.16 - 15 > > > > fio job: > > [rbd-test] > > readwrite=write > > blocksize=4M > > #runtime=60 > > name=rbd-test > > #readwrite=randwrite > > #bssplit=4k/85:32k/11:512/3:1m/1,4k/89:32k/10:512k/1 > > #rwmixread=72 > > #norandommap > > #size=1T > > #blocksize=4k > > ioengine=rbd > > rbdname=test2 > > pool=rbd > > clientname=admin > > iodepth=8 > > #numjobs=4 > > #thread > > #group_reporting > > #time_based > > #direct=1 > > #ramp_time=60 > > > > > > Thanks, > > -----BEGIN PGP SIGNATURE----- > > Version: Mailvelope v1.1.0 > > Comment: https://www.mailvelope.com > > > > wsFcBAEBCAAQBQJWAcaKCRDmVDuy+mK58QAAPMsQAKBnS94fwuw0OqpPU3/z > > tL8Z6TVRxrNigf721+2ClIu4LIH71bupDc3DgrrysQmmqGuvEMn68spmasWu > > h9I/CqqgRpHqe4lUVoUEjyWA9/6Dbb6NiHSdpJ6p5jpGc8kZCvNS+ocDgFOl > > 903i0M0E9eEMeci5O/hrMrx1FG8SN2LS8nI261aNHMOwQK0bw8wWiCJEvqVB > > sz1/+jK1BJoeIYfaT9HfUXBAvfo/W3tY/vj9KbJuZJ5AMpeYPvEHu/LAr1N7 > > FzzUc7a6EMlaxmSd0ML49JbV0cY9BMDjfrkKEQNKlzszlEHm3iif98QtsxbF > > pPJ0hZ0G53BY3k976OWVMFm3WFRWUVOb/oiLF8H6PCm59b4LBNAg6iPNH1AI > > 5XhEcPpg06M03vqUaIiY9P1kQlvnn0yCXf82IUEgmg///vhxDsHWmcwClLEn > > B0VszouStTzlMYnc/2vlUiI4gFVeilWLMW00VGTWV+7V1oIzIYvWHyl2QpBq > > 4/ZwVjQ43qLfuDTS4o+IJ4ztOMd26vIv6Mn6WVwKCjoCXJc8ajywR9Dy+6lL > > o8oJ+tn7hMc9Qy1iBhu3/QIP4WCsUf9RVeu60oahNEpde89qW32S9CZlrJDO > > gf4iTryRjkAhdmZIj9JiaE8jQ6dvN817D9cqs/CXKV9vhzYoM7p5YWHghBKB > > J3hS > > =0J7F > > -----END PGP SIGNATURE----- > > ---------------- > > Robert LeBlanc > > PGP Fingerprint 79A2 9CA4 6CC4 45DD A904 C70E E654 3BB2 FA62 B9F1 > > > > > > On Tue, Sep 22, 2015 at 8:31 AM, Gregory Farnum <gfar...@redhat.com> wrote: > >> On Tue, Sep 22, 2015 at 7:24 AM, Robert LeBlanc <rob...@leblancnet.us> > >> wrote: > >>> -----BEGIN PGP SIGNED MESSAGE----- > >>> Hash: SHA256 > >>> > >>> Is there some way to tell in the logs that this is happening? > >> > >> You can search for the (mangled) name _split_collection > >>> I'm not > >>> seeing much I/O, CPU usage during these times. Is there some way to > >>> prevent the splitting? Is there a negative side effect to doing so? > >> > >> Bump up the split and merge thresholds. You can search the list for > >> this, it was discussed not too long ago. > >> > >>> We've had I/O block for over 900 seconds and as soon as the sessions > >>> are aborted, they are reestablished and complete immediately. > >>> > >>> The fio test is just a seq write, starting it over (rewriting from the > >>> beginning) is still causing the issue. I was suspect that it is not > >>> having to create new file and therefore split collections. This is on > >>> my test cluster with no other load. > >> > >> Hmm, that does make it seem less likely if you're really not creating > >> new objects, if you're actually running fio in such a way that it's > >> not allocating new FS blocks (this is probably hard to set up?). > >> > >>> > >>> I'll be doing a lot of testing today. Which log options and depths > >>> would be the most helpful for tracking this issue down? > >> > >> If you want to go log diving "debug osd = 20", "debug filestore = 20", > >> "debug ms = 1" are what the OSD guys like to see. That should spit out > >> everything you need to track exactly what each Op is doing. > >> -Greg > > -- > > 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
