On 03/10/15 10:59, Merla, ShivaKrishna wrote: >>> 03/09/2015 11:07:54 AM >>> Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz >> await r_await w_await svctm %util >>> sdak 0.00 0.00 0.00 21737.00 0.00 101064.00 9.30 11.93 0.55 >> 0.00 0.55 0.04 93.00 >>> sdu 0.00 0.00 0.00 21759.00 0.00 101728.00 9.35 11.55 0.53 >> 0.00 0.53 0.04 93.60 >>> sdm 0.00 0.00 0.00 21669.00 0.00 101168.00 9.34 11.76 0.54 >> 0.00 0.54 0.04 94.00 >>> sdac 0.00 0.00 0.00 21812.00 0.00 101540.00 9.31 11.74 0.54 >> 0.00 0.54 0.04 92.50 >>> dm-6 0.00 14266.00 0.00 86980.00 0.00 405496.00 9.32 48.44 >> 0.56 0.00 0.56 0.01 98.70 >>> >>> With tunable delay of 20us here are the results. >>> >>> 03/09/2015 11:08:43 AM >>> Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz >> await r_await w_await svctm %util >>> sdak 0.00 0.00 0.00 11740.00 0.00 135344.00 23.06 4.42 0.38 >> 0.00 0.38 0.05 62.60 >>> sdu 0.00 0.00 0.00 11781.00 0.00 140800.00 23.90 3.23 0.27 >> 0.00 0.27 0.05 62.80 >>> sdm 0.00 0.00 0.00 11770.00 0.00 137592.00 23.38 4.53 0.39 >> 0.00 0.39 0.06 65.60 >>> sdac 0.00 0.00 0.00 11664.00 0.00 137976.00 23.66 3.36 0.29 >> 0.00 0.29 0.05 60.80 >>> dm-6 0.00 88446.00 0.00 46937.00 0.00 551684.00 23.51 17.88 >> 0.38 0.00 0.38 0.02 99.30 >> >> Oh I see. Thank you. >> So it's not that requests weren't queued for merging but that CPUs >> could not pile the requests fast enough... >> >> If possible, it would be interesting to see the results with much >> lower device queue_depth like 4 or 2. > I think very low queue_depths will lead multipath_busy() to return 1 > even in case of large number of paths. Hence leads to better I/O merging. Yes. But it didn't help very much.. > queue_depth 2 > > 03/09/2015 08:47:04 PM > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util > sdak 0.00 0.00 0.00 10512.00 0.00 106512.00 20.26 12.60 1.20 0.00 1.20 0.10 100.00 > sdu 0.00 0.00 0.00 10546.00 0.00 105728.00 20.05 12.92 1.23 0.00 1.23 0.09 100.00 > sdm 0.00 0.00 0.00 10518.00 0.00 106108.00 20.18 12.80 1.22 0.00 1.22 0.09 99.90 > sdac 0.00 0.00 0.00 10548.00 0.00 106100.00 20.12 13.10 1.24 0.00 1.24 0.09 100.00 > dm-6 0.00 62581.00 0.00 42122.00 0.00 424420.00 20.15 53.77 1.28 0.00 1.28 0.02 100.00 > > queue_depth 4 > > 03/09/2015 08:54:27 PM > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util > sdak 0.00 0.00 0.00 15671.00 0.00 109292.00 13.95 8.64 0.55 0.00 0.55 0.06 99.80 > sdu 0.00 0.00 0.00 15733.00 0.00 109204.00 13.88 8.34 0.53 0.00 0.53 0.06 99.40 > sdm 0.00 0.00 0.00 15779.00 0.00 106788.00 13.54 8.57 0.54 0.00 0.54 0.06 99.50 > sdac 0.00 0.00 0.00 15611.00 0.00 109568.00 14.04 8.31 0.53 0.00 0.53 0.06 98.70 > dm-6 0.00 44626.00 0.00 62795.00 0.00 434832.00 13.85 36.12 0.58 0.00 0.58 0.02 100.00 -- Jun'ichi Nomura, NEC Corporation -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
