https://bugzilla.suse.com/show_bug.cgi?id=1179404 https://bugzilla.suse.com/show_bug.cgi?id=1179404#c2 --- Comment #2 from Jan Kara --- FWIW I've verified that dobby is indeed using megaraid_sas driver. -- You are receiving this mail because: You are the assignee for the bug.

https://bugzilla.suse.com/show_bug.cgi?id=1179404 https://bugzilla.suse.com/show_bug.cgi?id=1179404#c4 Jan Kara changed: What |Removed |Added ---------------------------------------------------------------------------- Priority|P5 - None |P3 - Medium --- Comment #4 from Jan Kara --- OK, I have another set of results from dobby, this time with cpufreq performance governor enabled to avoid frequency scaling surprises. TLDR: results from the first run is confirmed: 5.10.0-rc5 5.10.0-rc5 vanilla megaraid-revert Amean 1 36.59 ( 0.00%) 36.41 * 0.49%* Amean 2 127.66 ( 0.00%) 95.83 * 24.94%* Amean 4 585.20 ( 0.00%) 513.57 * 12.24%* Amean 8 544.07 ( 0.00%) 348.76 * 35.90%* Amean 16 371.87 ( 0.00%) 237.78 * 36.06%* Amean 32 310.47 ( 0.00%) 242.73 * 21.82%* Amean 64 302.07 ( 0.00%) 256.75 * 15.00%* Amean 512 10390.57 ( 0.00%) 10701.90 * -3.00%* Now what is interesting is a comparison with mq-deadline IO scheduler: Amean 1 33.50 ( 0.00%) 34.97 * -4.41%* Amean 2 36.34 ( 0.00%) 38.33 * -5.47%* Amean 4 40.00 ( 0.00%) 40.96 * -2.40%* Amean 8 49.45 ( 0.00%) 50.02 * -1.15%* Amean 16 70.48 ( 0.00%) 71.70 * -1.74%* Amean 32 110.90 ( 0.00%) 112.30 * -1.26%* Amean 64 200.85 ( 0.00%) 200.80 ( 0.03%) Amean 512 9402.01 ( 0.00%) 9880.16 * -5.09%* So indeed with mq-deadline IO scheduler the megaraid commit is neutral (well, slightly positive but for dbench that's mostly within a noise). So it means the megaraid change is somehow interacting badly with the BFQ IO scheduler. On the positive side, higher end disks and thus mq-deadline is probably more common with these kinds of storage controllers. But let's investigate what upsets BFQ... I suspect multiple HW queues (which is what megaraid patch exposes AFAIU) somehow upset IO scheduling done by BFQ but I'm not even sure how IO scheduling is supposed to work with multiple HW queues so I have to investigate first. -- You are receiving this mail because: You are the assignee for the bug.