On Tue, 2020-02-11 at 16:19 -0800, Andrew Morton wrote: > On Tue, 11 Feb 2020 15:55:31 -0800 Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx> wrote: > > > On the host I just have to monitor /proc/meminfo and I can see the > > difference. I get the following results on the host, in the enabled case > > it takes about 30 seconds for it to settle into the final state since I > > only report page a bit at a time: > > Baseline/Applied > > MemTotal: 131963012 kB > > MemFree: 95189740 kB > > > > Enabled: > > MemTotal: 131963012 kB > > MemFree: 126459472 kB > > > > This is what I was referring to with the comment above. I had a test I was > > running back around the first RFC that consisted of bringing up enough VMs > > so that there was a bit of memory overcommit and then having the VMs in > > turn run memhog. As I recall the difference between the two was something > > like a couple minutes to run through all the VMs as the memhog would take > > up to 40+ seconds for one that was having to pull from swap while it took > > only 5 to 7 seconds for the VMs that were all running the page hinting. > > > > I had referenced it here in the RFC: > > https://lore.kernel.org/lkml/20190204181118.12095.38300.stgit@localhost.localdomain/ > > > > I have been verifying the memory has been getting freed but didn't feel > > like the test added much value so I haven't added it to the cover page for > > a while since the time could vary widely and is dependent on things like > > the disk type used for the host swap since my SSD is likely faster than > > spinning rust, but may not be as fast as other SSDs on the market. Since > > the disk speed can play such a huge role I wasn't comfortable posting > > numbers since the benefits could vary so widely. > > OK, thanks. I'll add the patches to the mm pile. The new > mm/page_reporting.c is unreviewed afaict, so I guess you own that for > now ;) > > It would be very nice to get some feedback from testers asserting "yes, > this really helped my workload" but I understand this sort of testing > is hard to obtain at this stage. > Mel, Any ETA on when you would be available to review these patches? They are now in Andrew's tree and in linux-next. I am hoping to get any remaining review from the community sorted out in the next few weeks so I can move onto focusing on how best to exert pressure on the page cache so that we can keep the guest memory footprint small. Thanks. - Alex
