On Thu, Aug 08, 2019 at 12:55:34AM +0100, Mel Gorman wrote: > On Thu, Aug 08, 2019 at 08:08:17AM +1000, Dave Chinner wrote: > > On Wed, Aug 07, 2019 at 04:03:16PM +0100, Mel Gorman wrote: > > > On Wed, Aug 07, 2019 at 11:30:56AM +0200, Michal Hocko wrote: > > > The boosting was not intended to target THP specifically -- it was meant > > > to help recover early from any fragmentation-related event for any user > > > that might need it. Hence, it's not tied to THP but even with THP > > > disabled, the boosting will still take effect. > > > > > > One band-aid would be to disable watermark boosting entirely when THP is > > > disabled but that feels wrong. However, I would be interested in hearing > > > if sysctl vm.watermark_boost_factor=0 has the same effect as your patch. > > > > <runs test> > > > > Ok, it still runs it out of page cache, but it doesn't drive page > > cache reclaim as hard once there's none left. The IO patterns are > > less peaky, context switch rates are increased from ~3k/s to 15k/s > > but remain pretty steady. > > > > Test ran 5s faster and file rate improved by ~2%. So it's better > > once the page cache is largerly fully reclaimed, but it doesn't > > prevent the page cache from being reclaimed instead of inodes.... > > > > Ok. Ideally you would also confirm the patch itself works as you want. > It *should* but an actual confirmation would be nice. Yup, I'll get to that later today. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
