On Fri, 6 Nov 2020 at 17:00, Mel Gorman <[email protected]> wrote: > > On Fri, Nov 06, 2020 at 02:33:56PM +0100, Vincent Guittot wrote: > > On Fri, 6 Nov 2020 at 13:03, Mel Gorman <[email protected]> wrote: > > > > > > On Wed, Nov 04, 2020 at 09:42:05AM +0000, Mel Gorman wrote: > > > > While it's possible that some other factor masked the impact of the > > > > patch, > > > > the fact it's neutral for two workloads in 5.10-rc2 is suspicious as it > > > > indicates that if the patch was implemented against 5.10-rc2, it would > > > > likely not have been merged. I've queued the tests on the remaining > > > > machines to see if something more conclusive falls out. > > > > > > > > > > It's not as conclusive as I would like. fork_test generally benefits > > > across the board but I do not put much weight in that. > > > > > > Otherwise, it's workload and machine-specific. > > > > > > schbench: (wakeup latency sensitive), all machines benefitted from the > > > revert at the low utilisation except one 2-socket haswell machine > > > which showed higher variability when the machine was fully > > > utilised. > > > > There is a pending patch to should improve this bench: > > https://lore.kernel.org/patchwork/patch/1330614/ > > > > Ok, I've slotted this one in with a bunch of other stuff I wanted to run > over the weekend. That particular patch was on my radar anyway. It just > got bumped up the schedule a little bit. > > > > hackbench: Neutral except for the same 2-socket Haswell machine which > > > took an 8% performance penalty of 8% for smaller number of groups > > > and 4% for higher number of groups. > > > > > > pipetest: Mostly neutral except for the *same* machine showing an 18% > > > performance gain by reverting. > > > > > > kernbench: Shows small gains at low job counts across the board -- 0.84% > > > lowest gain up to 5.93% depending on the machine > > > > > > gitsource: low utilisation execution of the git test suite. This was > > > mostly a win for the revert. For the list of machines tested it > > > was > > > > > > 14.48% gain (2 socket but SNC enabled to 4 NUMA nodes) > > > neutral (2 socket broadwell) > > > 36.37% gain (1 socket skylake machine) > > > 3.18% gain (2 socket broadwell) > > > 4.4% (2 socket EPYC 2) > > > 1.85% gain (2 socket EPYC 1) > > > > > > While it was clear-cut for 5.9, it's less clear-cut for 5.10-rc2 although > > > the gitsource shows some severe differences depending on the machine that > > > is worth being extremely cautious about. I would still prefer a revert > > > but I'm also extremely biased and I know there are other patches in the > > > > This one from Julia can also impact > > > > Which one? I'm guessing "[PATCH v2] sched/fair: check for idle core"
Yes, Sorry I sent my answer before adding the link > > -- > Mel Gorman > SUSE Labs
