Re: [PATCH] vmscan: prevent background aging of anon page in no swap system

From: KOSAKI Motohiro
Date: Mon Aug 30 2010 - 21:18:45 EST


> Hi, KOSAKI.
>
> On Tue, Aug 31, 2010 at 9:56 AM, KOSAKI Motohiro
> <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
> >> diff --git a/mm/vmscan.c b/mm/vmscan.c
> >> index 1b145e6..0b8a3ce 100644
> >> --- a/mm/vmscan.c
> >> +++ b/mm/vmscan.c
> >> @@ -1747,7 +1747,7 @@ static void shrink_zone(int priority, struct zone *zone,
> >>          * Even if we did not try to evict anon pages at all, we want to
> >>          * rebalance the anon lru active/inactive ratio.
> >>          */
> >> -       if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0)
> >> +       if (nr_swap_pges > 0 && inactive_anon_is_low(zone, sc))
> >
> > Sorry, I don't find any difference. What is your intention?
> >
>
> My intention is that smart gcc can compile out inactive_anon_is_low
> call in case of non swap configurable system.

Do you really check it on your gcc? nr_swap_pages is not file scope variable, it's
global variable. afaik, current gcc's link time optimization is not so cool.

Do you have a disassemble list?



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