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.
