On Sun, Oct 11, 2009 at 08:35:36PM +0200, Jens Axboe wrote: > It depends a lot on the workload. The UT will trigger if the amount of > writes isn't very high - if you go above 4 queued writes, a regular > unplug will trigger. So if you see if for write intensive workloads, it > is almost surely a bug. For background firefox activity on your desktop, > it's not unusual. > > If you see if for reads, it's almost always a bug. Ok, so this came up because we're having performance issues on a NFS head which serves files on XFS from a bunch of AOE devices. iostat is reporting near-100% utilization for the device I've traced here, /dev/etherd/e7.0. I noticed blkparse doesn't seem to run anywhere (it takes the local number of CPUs even though the trace may have involved more?), so I've uploaded blkparse output from the trace machine: http://0x.ca/sim/ref/2.6.30.5-hw-fixedxfs/blkparse_out.txt.gz http://0x.ca/sim/ref/2.6.30.5-hw-fixedxfs/blkparse-t_out.txt.gz See near the beginning of that, CPU #7: 152,32 7 5 0.006609360 3228 C R 7739498616 + 248 ( 4103734) [0] 152,32 7 6 0.007504725 2787 A R 4393342696 + 248 <- (252,43) 98375016 152,32 7 7 0.007505633 2787 Q R 4393342696 + 248 [nfsd] 152,32 7 8 0.007507379 2787 G R 4393342696 + 248 [nfsd] 152,32 7 9 0.007509055 2787 P N [nfsd] 152,32 7 10 0.007514922 2787 I R 4393342696 + 248 ( 7543) [nfsd] 152,32 7 11 0.007520998 2787 A R 4393342944 + 8 <- (252,43) 98375264 152,32 7 12 0.007521696 2787 Q R 4393342944 + 8 [nfsd] 152,32 7 13 0.007528750 2787 G R 4393342944 + 8 [nfsd] 152,32 7 14 0.007529519 2787 I R 4393342944 + 8 ( 769) [nfsd] 152,32 7 15 0.011107417 0 UT N [swapper] 3 152,32 7 16 0.011121386 207 U N [kblockd/7] 3 152,32 7 17 0.011129347 207 D R 4393342696 + 248 ( 3614425) [kblockd/7] Is that a bug? Simon- -- To unsubscribe from this list: send the line "unsubscribe linux-btrace" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
