From: Mel Gorman <mgorman@suse.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 12/13] mm: numa: Scan pages with elevated page_mapcount
Date: Thu, 4 Jul 2013 10:27:41 +0100 [thread overview]
Message-ID: <20130704092741.GM1875@suse.de> (raw)
In-Reply-To: <20130703183517.GC18898@dyad.programming.kicks-ass.net>
On Wed, Jul 03, 2013 at 08:35:17PM +0200, Peter Zijlstra wrote:
> On Wed, Jul 03, 2013 at 03:21:39PM +0100, Mel Gorman wrote:
> > Initial support for automatic NUMA balancing was unable to distinguish
> > between false shared versus private pages except by ignoring pages with an
> > elevated page_mapcount entirely. This patch kicks away the training wheels
> > as initial support for identifying shared/private pages is now in place.
> > Note that the patch still leaves shared, file-backed in VM_EXEC vmas in
> > place guessing that these are shared library pages. Migrating them are
> > likely to be of major benefit as generally the expectation would be that
> > these are read-shared between caches and that iTLB and iCache pressure is
> > generally low.
>
> This reminds me; there a clause in task_numa_work() that skips 'small' VMAs. I
> don't see the point of that.
>
It was a stupid hack initially to keep scan rates down and it was on the
TODO list to get rid of it and replace it with something else. I'll just
get rid of it for now without the replacement. Patch looks like this.
---8<---
sched: Remove check that skips small VMAs
task_numa_work skips small VMAs. At the time the logic was to reduce the
scanning overhead which was considerable. It is a dubious hack at best. It
would make much more sense to cache where faults have been observed and
only rescan those regions during subsequent PTE scans. Remove this hack
as motivation to do it properly in the future.
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
kernel/sched/fair.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3d34c6e..921265b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1075,10 +1075,6 @@ void task_numa_work(struct callback_head *work)
if (!vma_migratable(vma))
continue;
- /* Skip small VMAs. They are not likely to be of relevance */
- if (vma->vm_end - vma->vm_start < HPAGE_SIZE)
- continue;
-
do {
start = max(start, vma->vm_start);
end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE);
--
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:[~2013-07-04 9:27 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-03 14:21 [PATCH 0/13] Basic scheduler support for automatic NUMA balancing V2 Mel Gorman
2013-07-03 14:21 ` [PATCH 01/13] mm: numa: Document automatic NUMA balancing sysctls Mel Gorman
2013-07-03 14:21 ` [PATCH 02/13] sched: Track NUMA hinting faults on per-node basis Mel Gorman
2013-07-03 14:21 ` [PATCH 03/13] sched: Select a preferred node with the most numa hinting faults Mel Gorman
2013-07-03 14:21 ` [PATCH 04/13] sched: Update NUMA hinting faults once per scan Mel Gorman
2013-07-03 14:21 ` [PATCH 05/13] sched: Favour moving tasks towards the preferred node Mel Gorman
2013-07-03 14:21 ` [PATCH 06/13] sched: Reschedule task on preferred NUMA node once selected Mel Gorman
2013-07-04 12:26 ` Srikar Dronamraju
2013-07-04 13:29 ` Mel Gorman
2013-07-03 14:21 ` [PATCH 07/13] sched: Split accounting of NUMA hinting faults that pass two-stage filter Mel Gorman
2013-07-03 21:56 ` Johannes Weiner
2013-07-04 9:23 ` Mel Gorman
2013-07-04 14:24 ` Rik van Riel
2013-07-04 19:36 ` Johannes Weiner
2013-07-05 9:41 ` Mel Gorman
2013-07-05 10:48 ` Peter Zijlstra
2013-07-03 14:21 ` [PATCH 08/13] sched: Increase NUMA PTE scanning when a new preferred node is selected Mel Gorman
2013-07-03 14:21 ` [PATCH 09/13] sched: Favour moving tasks towards nodes that incurred more faults Mel Gorman
2013-07-03 18:27 ` Peter Zijlstra
2013-07-04 9:25 ` Mel Gorman
2013-07-03 14:21 ` [PATCH 10/13] sched: Set the scan rate proportional to the size of the task being scanned Mel Gorman
2013-07-03 14:21 ` [PATCH 11/13] sched: Check current->mm before allocating NUMA faults Mel Gorman
2013-07-03 15:33 ` Mel Gorman
2013-07-04 12:48 ` Srikar Dronamraju
2013-07-05 10:07 ` Mel Gorman
2013-07-03 14:21 ` [PATCH 12/13] mm: numa: Scan pages with elevated page_mapcount Mel Gorman
2013-07-03 18:35 ` Peter Zijlstra
2013-07-04 9:27 ` Mel Gorman [this message]
2013-07-03 18:41 ` Peter Zijlstra
2013-07-04 9:32 ` Mel Gorman
2013-07-03 18:42 ` Peter Zijlstra
2013-07-03 14:21 ` [PATCH 13/13] sched: Account for the number of preferred tasks running on a node when selecting a preferred node Mel Gorman
2013-07-03 18:32 ` Peter Zijlstra
2013-07-04 9:37 ` Mel Gorman
2013-07-04 13:07 ` Srikar Dronamraju
2013-07-04 13:54 ` Mel Gorman
2013-07-04 14:06 ` Peter Zijlstra
2013-07-04 14:40 ` Mel Gorman
2013-07-03 16:19 ` [PATCH 0/13] Basic scheduler support for automatic NUMA balancing V2 Mel Gorman
2013-07-03 16:26 ` Mel Gorman
2013-07-04 18:02 ` [PATCH RFC WIP] Process weights based scheduling for better consolidation Srikar Dronamraju
2013-07-05 10:16 ` Peter Zijlstra
2013-07-05 12:49 ` Srikar Dronamraju
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=20130704092741.GM1875@suse.de \
--to=mgorman@suse.de \
--cc=aarcange@redhat.com \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=srikar@linux.vnet.ibm.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).