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.
