On 2011.06.29 at 17:24 +1000, Dave Chinner wrote: > On Wed, Jun 29, 2011 at 08:19:54AM +0200, Markus Trippelsdorf wrote: > > On 2011.06.29 at 14:31 +1000, Dave Chinner wrote: > > > On Wed, Jun 22, 2011 at 05:30:47PM +1000, Dave Chinner wrote: > > > > Jun 22 08:53:09 x4 kernel: XFS (sdb1): ail: ooo splice, tail 0x12000156e7, item 0x12000156e6 > > > > Jun 22 08:53:09 x4 kernel: XFS (sdb1): ail: ooo splice, walked 15503 items > > > > ..... > > > > Jun 22 08:53:12 x4 kernel: XFS (sdb1): ail: ooo splice, tail 0x12000156e7, item 0x12000156e6 > > > > Jun 22 08:53:12 x4 kernel: XFS (sdb1): ail: ooo splice, walked 16945 items > > > > > > > > Interesting is the LSN of the tail - it's only one sector further on > > > > than the items being inserted. That's what I'd expect from a commit > > > > record write race between two checkpoints. I'll have a deeper look > > > > into whether this can be avoided later tonight and also whether I > > > > can easily implement a "last insert cursor" easily so subsequent > > > > inserts at the same LSN avoid the walk.... > > > > > > Ok, so here's a patch that does just this. I should probably also do > > > a little bit of cleanup on the cursor code as well, but this avoids > > > the repeated walks of the AIL to find the insert position. > > > > > > Can you try it without the WQ changes you made, Marcus, and see if > > > the interactivity problems go away? > > > > Sorry to be the bringer of bad news, but this made things much worse: > > > > -------cpu0-usage--------------cpu1-usage--------------cpu2-usage--------------cpu3-usage------ --dsk/sdc-- ---system-- ---load-avg--- --dsk/sdc-- > > usr sys idl wai hiq siq:usr sys idl wai hiq siq:usr sys idl wai hiq siq:usr sys idl wai hiq siq| read writ| int csw | 1m 5m 15m |reads writs > > 1 1 98 0 0 0: 0 1 99 0 0 0: 0 1 99 0 0 0: 0 1 99 0 0 0| 0 0 | 603 380 |0.66 0.55 0.28| 0 0 > > 1 0 99 0 0 0: 1 0 99 0 0 0: 1 19 80 0 0 0: 0 0 100 0 0 0| 0 0 | 719 383 |0.66 0.55 0.28| 0 0 > > 3 1 96 0 0 0: 3 1 96 0 0 0: 1 52 47 0 0 0: 0 0 100 0 0 0| 0 6464k|1847 919 |0.66 0.55 0.28| 0 202 > > 2 13 85 0 0 0: 2 2 96 0 0 0: 1 56 43 0 0 0: 1 31 69 0 0 0|4096B 256k|1910 1280 |0.68 0.56 0.28| 1 8 > > > 0 1 99 0 0 0: 0 0 100 0 0 0: 0 1 99 0 0 0: 0 100 0 0 0 0| 0 0 |1256 170 |0.68 0.56 0.28| 0 0 > > > 0 1 99 0 0 0: 1 1 98 0 0 0: 1 0 99 0 0 0: 0 99 0 0 0 1| 0 0 |1395 229 |0.68 0.56 0.28| 0 0 > > > 0 0 100 0 0 0: 0 0 100 0 0 0: 0 3 97 0 0 0: 0 100 0 0 0 0| 0 512B|1304 167 |0.68 0.56 0.28| 0 1 > > > 1 1 98 0 0 0: 1 1 98 0 0 0: 0 0 100 0 0 0: 0 99 0 0 0 1| 0 0 |1211 146 |0.68 0.56 0.28| 0 0 > > > 0 0 100 0 0 0: 0 0 100 0 0 0: 0 1 99 0 0 0: 0 97 0 0 0 3| 0 0 |1270 149 |0.87 0.60 0.30| 0 0 > > 5 2 65 29 0 0: 2 3 95 0 0 0: 1 0 99 0 0 0: 2 24 72 0 0 1| 0 8866k|2654 2398 |0.87 0.60 0.30| 0 496 > > 6 2 25 67 0 0: 3 1 59 37 0 0: 0 0 100 0 0 0: 4 4 92 0 0 0| 0 4554k|2224 2494 |0.87 0.60 0.30| 0 399 > > 1 1 98 0 0 0: 0 0 83 17 0 0: 1 3 96 0 0 0: 0 1 99 0 0 0| 0 2270k|1079 1030 |0.87 0.60 0.30| 0 200 > > 1 1 98 0 0 0: 1 1 98 0 0 0: 0 1 99 0 0 0: 1 0 99 0 0 0| 0 9216B| 713 567 |0.87 0.60 0.30| 0 2 > > 0 0 100 0 0 0: 1 1 98 0 0 0: 0 0 100 0 0 0: 0 1 99 0 0 0| 0 0 | 492 386 |0.80 0.59 0.30| 0 0 > > > > As you can see in the table above (resolution 1sec) the hang is now > > 5-6 seconds long, instead of the 1-3 seconds seen before. > > Interesting. I checked that the ordering was correct in each case > adn that it was behaving correctly here. > > Can you add the following patch and send me the dmesg output over a > hang? It will tell me where the cursor is being initialised and when > it is being dropped, so should indicate if a specific insert chain > is getting stuck or doing something stoopid. The kernel log is attached. rm -fr && sync starts at Jun 29 09:32:24. -- Markus
Attachment:
kern_.log.bz2
Description: BZip2 compressed data
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