Messages in this thread | | | Date | Thu, 29 Sep 2005 16:24:02 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] vm - swap_prefetch v12 |
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Con Kolivas <kernel@kolivas.org> wrote: > > On Fri, 30 Sep 2005 07:54 am, Andrew Morton wrote: > > Con Kolivas <kernel@kolivas.org> wrote: > > > Once pages have been added to the swapped list, a timer is started, > > > testing for conditions suitable to prefetch swap pages every 5 seconds. > > > Suitable conditions are defined as lack of swapping out or in any pages, > > > and no watermark tests failing. Significant amounts of dirtied ram also > > > prevent prefetching. It then checks that we have spare ram looking for at > > > least 3* pages_high free per zone and if it succeeds that will prefetch > > > pages from swap. > > > > Did you consider poking around in gendisk.disk_stats to determine whether > > the swap disk(s) are idleish? > > I didn't know where to look for that info. Thanks! I'm open to *any* > suggestions and I'll look into it as I can't take this code much further > without outside help. >
Might also be able to utilise CFQ's I/O priorities. That should be more efective than a heuristic based on disk_stats, however you'd probably need to work out whether the swapdev actually supports IO priorities and I'm not sure how one would query that (cleanly).
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