All of lore.kernel.org
 help / color / mirror / Atom feed
From: Michal Hocko <mhocko@kernel.org>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Minchan Kim <minchan@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@techsingularity.net>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch v2] mm, vmscan: avoid thrashing anon lru when free + file is low
Date: Wed, 3 May 2017 09:06:56 +0200	[thread overview]
Message-ID: <20170503070656.GA8836@dhcp22.suse.cz> (raw)
In-Reply-To: <20170503061528.GB1236@dhcp22.suse.cz>

On Wed 03-05-17 08:15:28, Michal Hocko wrote:
> On Tue 02-05-17 13:41:23, David Rientjes wrote:
> > On Tue, 2 May 2017, Michal Hocko wrote:
[...]
> > > I do agree that blindly
> > > scanning anon pages when file pages are low is very suboptimal but this
> > > adds yet another heuristic without _any_ numbers. Why cannot we simply
> > > treat anon and file pages equally? Something like the following
> > > 
> > > 	if (pgdatfile + pgdatanon + pgdatfree > 2*total_high_wmark) {
> > > 		scan_balance = SCAN_FILE;
> > > 		if (pgdatfile < pgdatanon)
> > > 			scan_balance = SCAN_ANON;
> > > 		goto out;
> > > 	}
> > > 
> > 
> > This would be substantially worse than the current code because it 
> > thrashes the anon lru when anon out numbers file pages rather than at the 
> > point we fall under the high watermarks for all eligible zones.  If you 
> > tested your suggestion, you could see gigabytes of memory left untouched 
> > on the file lru.  Anonymous memory is more probable to be part of the 
> > working set.
> 
> This was supposed to be more an example of a direction I was thinking,
> definitely not a final patch. I will think more to come up with a
> more complete proposal.

This is still untested but should be much closer to what I've had in
mind.
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 24efcc20af91..bcdad30f942d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2174,8 +2174,14 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 		}
 
 		if (unlikely(pgdatfile + pgdatfree <= total_high_wmark)) {
-			scan_balance = SCAN_ANON;
-			goto out;
+			unsigned long pgdatanon;
+
+			pgdatanon = node_page_state(pgdat, NR_ACTIVE_ANON) +
+				node_page_state(pgdat, NR_INACTIVE_ANON);
+			if (pgdatanon + pgdatfree > total_high_wmark) {
+				scan_balance = SCAN_ANON;
+				goto out;
+			}
 		}
 	}
 

-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Minchan Kim <minchan@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@techsingularity.net>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch v2] mm, vmscan: avoid thrashing anon lru when free + file is low
Date: Wed, 3 May 2017 09:06:56 +0200	[thread overview]
Message-ID: <20170503070656.GA8836@dhcp22.suse.cz> (raw)
In-Reply-To: <20170503061528.GB1236@dhcp22.suse.cz>

On Wed 03-05-17 08:15:28, Michal Hocko wrote:
> On Tue 02-05-17 13:41:23, David Rientjes wrote:
> > On Tue, 2 May 2017, Michal Hocko wrote:
[...]
> > > I do agree that blindly
> > > scanning anon pages when file pages are low is very suboptimal but this
> > > adds yet another heuristic without _any_ numbers. Why cannot we simply
> > > treat anon and file pages equally? Something like the following
> > > 
> > > 	if (pgdatfile + pgdatanon + pgdatfree > 2*total_high_wmark) {
> > > 		scan_balance = SCAN_FILE;
> > > 		if (pgdatfile < pgdatanon)
> > > 			scan_balance = SCAN_ANON;
> > > 		goto out;
> > > 	}
> > > 
> > 
> > This would be substantially worse than the current code because it 
> > thrashes the anon lru when anon out numbers file pages rather than at the 
> > point we fall under the high watermarks for all eligible zones.  If you 
> > tested your suggestion, you could see gigabytes of memory left untouched 
> > on the file lru.  Anonymous memory is more probable to be part of the 
> > working set.
> 
> This was supposed to be more an example of a direction I was thinking,
> definitely not a final patch. I will think more to come up with a
> more complete proposal.

This is still untested but should be much closer to what I've had in
mind.
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 24efcc20af91..bcdad30f942d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2174,8 +2174,14 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 		}
 
 		if (unlikely(pgdatfile + pgdatfree <= total_high_wmark)) {
-			scan_balance = SCAN_ANON;
-			goto out;
+			unsigned long pgdatanon;
+
+			pgdatanon = node_page_state(pgdat, NR_ACTIVE_ANON) +
+				node_page_state(pgdat, NR_INACTIVE_ANON);
+			if (pgdatanon + pgdatfree > total_high_wmark) {
+				scan_balance = SCAN_ANON;
+				goto out;
+			}
 		}
 	}
 

-- 
Michal Hocko
SUSE Labs

--
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>

  reply	other threads:[~2017-05-03  7:07 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-18  0:06 [patch] mm, vmscan: avoid thrashing anon lru when free + file is low David Rientjes
2017-04-18  0:06 ` David Rientjes
2017-04-18  1:36 ` Minchan Kim
2017-04-18  1:36   ` Minchan Kim
2017-04-18 21:32   ` David Rientjes
2017-04-18 21:32     ` David Rientjes
2017-04-19  0:14     ` Minchan Kim
2017-04-19  0:14       ` Minchan Kim
2017-04-19 23:24       ` David Rientjes
2017-04-19 23:24         ` David Rientjes
2017-04-20  6:09         ` Minchan Kim
2017-04-20  6:09           ` Minchan Kim
2017-05-01 21:34           ` [patch v2] " David Rientjes
2017-05-01 21:34             ` David Rientjes
2017-05-02  8:02             ` Michal Hocko
2017-05-02  8:02               ` Michal Hocko
2017-05-02 20:41               ` David Rientjes
2017-05-02 20:41                 ` David Rientjes
2017-05-03  6:15                 ` Michal Hocko
2017-05-03  6:15                   ` Michal Hocko
2017-05-03  7:06                   ` Michal Hocko [this message]
2017-05-03  7:06                     ` Michal Hocko
2017-05-03  8:49                     ` Michal Hocko
2017-05-03  8:49                       ` Michal Hocko
2017-05-03 22:52                       ` David Rientjes
2017-05-03 22:52                         ` David Rientjes
2017-05-04 11:43                         ` Michal Hocko
2017-05-04 11:43                           ` Michal Hocko
2017-05-31 15:20             ` Michal Hocko
2017-05-31 15:20               ` Michal Hocko
2017-06-02 20:36             ` Andrew Morton
2017-06-02 20:36               ` Andrew Morton
2017-06-04 22:27               ` David Rientjes
2017-06-04 22:27                 ` David Rientjes
2017-04-19  7:04     ` [patch] " Michal Hocko
2017-04-19  7:04       ` Michal Hocko
2017-04-18  7:11 ` Michal Hocko
2017-04-18  7:11   ` Michal Hocko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170503070656.GA8836@dhcp22.suse.cz \
    --to=mhocko@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=hannes@cmpxchg.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mgorman@techsingularity.net \
    --cc=minchan@kernel.org \
    --cc=rientjes@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.