Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes: > On Thu, 21 Sep 2023 21:32:35 +0800 "Huang, Ying" <ying.huang@xxxxxxxxx> wrote: > >> > : It's possible that PCP high auto-tuning doesn't work well for some >> > : workloads. So, when PCP high is tuned by hand via the sysctl knob, >> > : the auto-tuning will be disabled. The PCP high set by hand will be >> > : used instead. >> > >> > Is it a bit hacky to disable autotuning when the user alters >> > pcp-high? Would it be cleaner to have a separate on/off knob for >> > autotuning? >> >> This was suggested by Mel Gormon, >> >> https://lore.kernel.org/linux-mm/20230714140710.5xbesq6xguhcbyvi@xxxxxxxxxxxxxxxxxxx/ >> >> " >> I'm not opposed to having an adaptive pcp->high in concept. I think it would >> be best to disable adaptive tuning if percpu_pagelist_high_fraction is set >> though. I expect that users of that tunable are rare and that if it *is* >> used that there is a very good reason for it. >> " >> >> Do you think that this is reasonable? > > I suppose so, if it's documented! > > Documentation/admin-guide/sysctl/vm.rst describes > percpu_pagelist_high_fraction. Sure. Will add document about auto-tuning behavior in the above document. -- Best Regards, Huang, Ying
