On Thu, 19 Jan 2012 09:42:59 -0500 Rik van Riel <riel@xxxxxxxxxx> wrote: > On 01/18/2012 09:25 PM, KAMEZAWA Hiroyuki wrote: > > On Wed, 18 Jan 2012 09:17:17 -0500 > > Rik van Riel<riel@xxxxxxxxxx> wrote: > > > >> On 01/17/2012 07:18 PM, KAMEZAWA Hiroyuki wrote: > >>> On Wed, 18 Jan 2012 08:08:01 +0900 > >>> Minchan Kim<minchan@xxxxxxxxxx> wrote: > >>> > >>>>>>> 2. can't we measure page-in/page-out distance by recording something ? > >>>>>> > >>>>>> I can't understand your point. What's relation does it with swapout prevent? > >>>>>> > >>>>> > >>>>> If distance between pageout -> pagein is short, it means thrashing. > >>>>> For example, recoding the timestamp when the page(mapping, index) was > >>>>> paged-out, and check it at page-in. > >>>> > >>>> Our goal is prevent swapout. When we found thrashing, it's too late. > >>> > >>> If you want to prevent swap-out, don't swapon any. That's all. > >>> Then, you can check the number of FILE_CACHE and have threshold. > >> > >> I think you are getting hung up on a word here. > >> > >> As I understand it, the goal is to push out the point where > >> we start doing heavier swap IO, allowing us to overcommit > >> memory more heavily before things start really slowing down. > >> > > > > Yes. > > > > Hmm, considering that the issue is slow down, > > > > time values as > > > > - 'cpu time used for memory reclaim' > > - 'latency of page allocation' > > - 'application execution speed' ? > > > > may be a better score to see rather than just seeing lru's stat. > > I believe those all qualify as "too late". > > We want to prevent things from becoming bad, for as long > as we (easily) can. > Hmm, then some threshold-notifier interface will be required. Problem is how to know free + page_can_be_freed_without_risk. Thanks, -Kame -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>