Messages in this thread | | | Date | Thu, 19 Jan 2012 09:42:59 -0500 | From | Rik van Riel <> | Subject | Re: [RFC 2/3] vmscan hook |
| |
On 01/18/2012 09:25 PM, KAMEZAWA Hiroyuki wrote: > On Wed, 18 Jan 2012 09:17:17 -0500 > Rik van Riel<riel@redhat.com> wrote: > >> On 01/17/2012 07:18 PM, KAMEZAWA Hiroyuki wrote: >>> On Wed, 18 Jan 2012 08:08:01 +0900 >>> Minchan Kim<minchan@kernel.org> 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.
-- All rights reversed
| |