Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 7 Nov 2011 11:29:41 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [rfc 1/3] mm: vmscan: never swap under low memory pressure |
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On Wed, 2 Nov 2011 17:31:41 +0100 Johannes Weiner <jweiner@redhat.com> wrote:
> We want to prevent floods of used-once file cache pushing us to swap > out anonymous pages. Never swap under a certain priority level. The > availability of used-once cache pages should prevent us from reaching > that threshold. > > This is needed because subsequent patches will revert some of the > mechanisms that tried to prefer file over anon, and this should not > result in more eager swapping again. > > It might also be better to keep the aging machinery going and just not > swap, rather than staying away from anonymous pages in the first place > and having less useful age information at the time of swapout. > > Signed-off-by: Johannes Weiner <jweiner@redhat.com> > --- > mm/vmscan.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index a90c603..39d3da3 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -831,6 +831,8 @@ static unsigned long shrink_page_list(struct list_head *page_list, > * Try to allocate it some swap space here. > */ > if (PageAnon(page) && !PageSwapCache(page)) { > + if (priority >= DEF_PRIORITY - 2) > + goto keep_locked; > if (!(sc->gfp_mask & __GFP_IO)) > goto keep_locked; > if (!add_to_swap(page))
Hm, how about not scanning LRU_ANON rather than checking here ? Add some bias to get_scan_count() or some.. If you think to need rotation of LRU, only kswapd should do that..
Thanks, -Kame
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