On Date: Mon, 9 Sep 2024 09:12:03 +0200 Michal Hocko <mhocko@xxxxxxxx> > On Fri 06-09-24 19:04:19, Hillf Danton wrote: > > On Thu, 5 Sep 2024 16:29:41 -0700 Davidlohr Bueso <dave@xxxxxxxxxxxx> > > > On Fri, 06 Sep 2024, Hillf Danton wrote:\n > > > >The proactive reclaim on the cmdline looks like waste of cpu cycles before > > > >the cases where kswapd fails to work are spotted. It is not correct to add > > > >it because you can type the code. > > > > > > Are you against proactive reclaim altogether (ie: memcg) or this patch in > > > particular, which extends its availability? > > > > > The against makes no sense to me because I know your patch is never able to > > escape standing ovation. > > I fail to understand your reasoning. Do you have any actual technical > arguments why this is a bad idea? > > > > The benefits of proactive reclaim are well documented, and the community has > > > been overall favorable towards it. This operation is not meant to be generally > > > used, but there are real latency benefits to be had which are completely > > > unrelated to watermarks. Similarly, we have 'compact' as an alternative to > > > kcompactd (which was once upon a time part of kswapd). > > > > > Because kswapd is responsible for watermark instead of high order pages, > > compact does not justify proactive reclaim from the begining. > > What do you mean? How does keeping a global watermark helps to trigger > per NUMA node specific aging - e.g. demotion? > In addition to the cost of pro/demorion, the percpu pages prevent random aging from making any sense without memory pressue, because I think it is aging that rolls out red carpet for multi-gen lru.
