On Wed, 22 Jul 2015 19:25:28 +0300 Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> wrote: > On Tue, Jul 21, 2015 at 04:35:00PM -0700, Andrew Morton wrote: > > On Sun, 19 Jul 2015 15:31:16 +0300 Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> wrote: > > > > > As noted by Minchan, a benefit of reading idle flag from > > > /proc/kpageflags is that one can easily filter dirty and/or unevictable > > > pages while estimating the size of unused memory. > > > > > > Note that idle flag read from /proc/kpageflags may be stale in case the > > > page was accessed via a PTE, because it would be too costly to iterate > > > over all page mappings on each /proc/kpageflags read to provide an > > > up-to-date value. To make sure the flag is up-to-date one has to read > > > /proc/kpageidle first. > > > > Is there any value in teaching the regular old page scanner to update > > these flags? If it's doing an rmap scan anyway... > > I don't understand what you mean by "regular old page scanner". Could > you please elaborate? Whenever kswapd or direct reclaim perform an rmap scan, take that as an opportunity to also update PageIdle(). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>