From: Minchan Kim <minchan@kernel.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dan Magenheimer <dan.magenheimer@oracle.com>, Sonny Rao <sonnyrao@google.com>, Bryan Freed <bfreed@google.com>, Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>, Johannes Weiner <hannes@cmpxchg.org> Subject: Re: [PATCH 2/2] mm: forcely swapout when we are out of page cache Date: Thu, 10 Jan 2013 11:23:06 +0900 [thread overview] Message-ID: <20130110022306.GB14685@blaptop> (raw) In-Reply-To: <20130109162602.53a60e77.akpm@linux-foundation.org> On Wed, Jan 09, 2013 at 04:26:02PM -0800, Andrew Morton wrote: > On Wed, 9 Jan 2013 15:21:14 +0900 > Minchan Kim <minchan@kernel.org> wrote: > > > If laptop_mode is enable, VM try to avoid I/O for saving the power. > > But if there isn't reclaimable memory without I/O, we should do I/O > > for preventing unnecessary OOM kill although we sacrifices power. > > > > One of example is that we are out of page cache. Remained one is > > only anonymous pages, for swapping out, we needs may_writepage = 1. > > > > Reported-by: Luigi Semenzato <semenzato@google.com> > > Signed-off-by: Minchan Kim <minchan@kernel.org> > > --- > > mm/vmscan.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 439cc47..624c816 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1728,6 +1728,12 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, > > free = zone_page_state(zone, NR_FREE_PAGES); > > if (unlikely(file + free <= high_wmark_pages(zone))) { > > scan_balance = SCAN_ANON; > > + /* > > + * From now on, we have to swap out > > + * for peventing OOM kill although > > + * we sacrifice power consumption. > > + */ > > + sc->may_writepage = 1; > > goto out; > > } > > } > > This is pretty ugly. get_scan_count() is, as its name implies, an > idempotent function which inspects the state of things and returns a > result. As such, it has no business going in and altering the state of > the scan_control. > > We have code in both direct reclaim and in kswapd to set may_writepage > if vmscan is getting into trouble. I don't see why adding another > instance is necessary if the existing instances are working correctly. > > > > (Is it correct that __zone_reclaim() ignores laptop_mode?) > > > I have a feeling that laptop mode has bitrotted and these patches are > kinda hacking around as-yet-not-understood failures... Absolutely, this patch is last guard for unexpectable behavior. As I mentioned in cover-letter, Luigi's problem could be solved either [1/2] or [2/2] but I wanted to add this as last resort in case of unexpected emergency. But you're right. It's not good to hide the problem like this path so let's drop [2/2]. Also, I absolutely agree it has bitrotted so for correcting it, we need a volunteer who have to inverstigate power saveing experiment with long time. So [1/2] would be band-aid until that. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kind regards, Minchan Kim
WARNING: multiple messages have this Message-ID (diff)
From: Minchan Kim <minchan@kernel.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dan Magenheimer <dan.magenheimer@oracle.com>, Sonny Rao <sonnyrao@google.com>, Bryan Freed <bfreed@google.com>, Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>, Johannes Weiner <hannes@cmpxchg.org> Subject: Re: [PATCH 2/2] mm: forcely swapout when we are out of page cache Date: Thu, 10 Jan 2013 11:23:06 +0900 [thread overview] Message-ID: <20130110022306.GB14685@blaptop> (raw) In-Reply-To: <20130109162602.53a60e77.akpm@linux-foundation.org> On Wed, Jan 09, 2013 at 04:26:02PM -0800, Andrew Morton wrote: > On Wed, 9 Jan 2013 15:21:14 +0900 > Minchan Kim <minchan@kernel.org> wrote: > > > If laptop_mode is enable, VM try to avoid I/O for saving the power. > > But if there isn't reclaimable memory without I/O, we should do I/O > > for preventing unnecessary OOM kill although we sacrifices power. > > > > One of example is that we are out of page cache. Remained one is > > only anonymous pages, for swapping out, we needs may_writepage = 1. > > > > Reported-by: Luigi Semenzato <semenzato@google.com> > > Signed-off-by: Minchan Kim <minchan@kernel.org> > > --- > > mm/vmscan.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 439cc47..624c816 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1728,6 +1728,12 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, > > free = zone_page_state(zone, NR_FREE_PAGES); > > if (unlikely(file + free <= high_wmark_pages(zone))) { > > scan_balance = SCAN_ANON; > > + /* > > + * From now on, we have to swap out > > + * for peventing OOM kill although > > + * we sacrifice power consumption. > > + */ > > + sc->may_writepage = 1; > > goto out; > > } > > } > > This is pretty ugly. get_scan_count() is, as its name implies, an > idempotent function which inspects the state of things and returns a > result. As such, it has no business going in and altering the state of > the scan_control. > > We have code in both direct reclaim and in kswapd to set may_writepage > if vmscan is getting into trouble. I don't see why adding another > instance is necessary if the existing instances are working correctly. > > > > (Is it correct that __zone_reclaim() ignores laptop_mode?) > > > I have a feeling that laptop mode has bitrotted and these patches are > kinda hacking around as-yet-not-understood failures... Absolutely, this patch is last guard for unexpectable behavior. As I mentioned in cover-letter, Luigi's problem could be solved either [1/2] or [2/2] but I wanted to add this as last resort in case of unexpected emergency. But you're right. It's not good to hide the problem like this path so let's drop [2/2]. Also, I absolutely agree it has bitrotted so for correcting it, we need a volunteer who have to inverstigate power saveing experiment with long time. So [1/2] would be band-aid until that. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2013-01-10 2:23 UTC|newest] Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-01-09 6:21 [PATCH 0/2] Use up free swap space before reaching OOM kill Minchan Kim 2013-01-09 6:21 ` [PATCH 1/2] mm: prevent to add a page to swap if may_writepage is unset Minchan Kim 2013-01-09 6:21 ` Minchan Kim 2013-01-09 6:56 ` Johannes Weiner 2013-01-09 6:56 ` Johannes Weiner 2013-01-09 7:10 ` Minchan Kim 2013-01-09 7:10 ` Minchan Kim 2013-01-10 0:18 ` Andrew Morton 2013-01-10 0:18 ` Andrew Morton 2013-01-10 2:03 ` Minchan Kim 2013-01-10 2:03 ` Minchan Kim 2013-01-10 23:24 ` Luigi Semenzato 2013-01-10 23:27 ` Luigi Semenzato 2013-01-10 23:27 ` Luigi Semenzato 2013-01-11 4:03 ` Minchan Kim 2013-01-11 4:03 ` Minchan Kim 2013-01-10 0:20 ` Andrew Morton 2013-01-10 0:20 ` Andrew Morton 2013-01-16 21:41 ` Andrew Morton 2013-01-16 21:41 ` Andrew Morton 2013-01-17 0:53 ` Minchan Kim 2013-01-17 0:53 ` Minchan Kim 2013-01-17 22:22 ` Andrew Morton 2013-01-17 22:22 ` Andrew Morton 2013-01-17 23:36 ` Minchan Kim 2013-01-17 23:36 ` Minchan Kim 2013-01-21 1:52 ` Minchan Kim 2013-01-21 1:52 ` Minchan Kim 2013-01-21 14:39 ` Rik van Riel 2013-01-21 14:39 ` Rik van Riel 2013-01-22 0:09 ` Minchan Kim 2013-01-22 0:09 ` Minchan Kim 2013-02-05 1:43 ` Minchan Kim 2013-02-05 1:43 ` Minchan Kim 2013-01-09 6:21 ` [PATCH 2/2] mm: forcely swapout when we are out of page cache Minchan Kim 2013-01-09 6:21 ` Minchan Kim 2013-01-10 0:26 ` Andrew Morton 2013-01-10 0:26 ` Andrew Morton 2013-01-10 2:23 ` Minchan Kim [this message] 2013-01-10 2:23 ` Minchan Kim 2013-01-10 21:58 ` Andrew Morton 2013-01-10 21:58 ` Andrew Morton 2013-01-11 4:43 ` Minchan Kim 2013-01-11 4:43 ` Minchan Kim 2013-01-16 0:09 ` Andrew Morton 2013-01-16 0:09 ` Andrew Morton 2013-01-16 0:32 ` Sonny Rao 2013-01-16 0:32 ` Sonny Rao 2013-01-16 0:50 ` Andrew Morton 2013-01-16 0:50 ` Andrew Morton 2013-01-16 1:21 ` Sonny Rao 2013-01-16 1:21 ` Sonny Rao 2013-01-16 4:47 ` Minchan Kim 2013-01-16 4:47 ` Minchan Kim 2013-01-16 20:08 ` Sonny Rao 2013-01-16 20:08 ` Sonny Rao 2013-01-16 4:43 ` Minchan Kim 2013-01-16 4:43 ` Minchan Kim
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