From: Peter Zijlstra <peterz@infradead.org>
To: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
Mel Gorman <mel@csn.ul.ie>,
Linux kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: question on NUMA page migration
Date: Fri, 19 Oct 2012 19:53:56 +0200 [thread overview]
Message-ID: <1350669236.2768.66.camel@twins> (raw)
In-Reply-To: <50818A41.7030909@redhat.com>
On Fri, 2012-10-19 at 13:13 -0400, Rik van Riel wrote:
> Would it make sense to have the normal page migration code always
> work with the extra refcount, so we do not have to introduce a new
> MIGRATE_FAULT migration mode?
>
> On the other hand, compaction does not take the extra reference...
Right, it appears to not do this, it gets pages from the pfn and
zone->lock and the isolate_lru_page() call is the first reference.
> Another alternative might be to do the put_page inside
> do_prot_none_numa(). That would be analogous to do_wp_page
> disposing of the old page for the caller.
It'd have to be inside migrate_misplaced_page(), can't do before
isolate_lru_page() or the page might disappear. Doing it after is
(obviously) too late.
> I am not real happy about NUMA migration introducing its own
> migration mode...
You didn't seem to mind too much earlier, but I can remove it if you
want.
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WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
Mel Gorman <mel@csn.ul.ie>,
Linux kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: question on NUMA page migration
Date: Fri, 19 Oct 2012 19:53:56 +0200 [thread overview]
Message-ID: <1350669236.2768.66.camel@twins> (raw)
In-Reply-To: <50818A41.7030909@redhat.com>
On Fri, 2012-10-19 at 13:13 -0400, Rik van Riel wrote:
> Would it make sense to have the normal page migration code always
> work with the extra refcount, so we do not have to introduce a new
> MIGRATE_FAULT migration mode?
>
> On the other hand, compaction does not take the extra reference...
Right, it appears to not do this, it gets pages from the pfn and
zone->lock and the isolate_lru_page() call is the first reference.
> Another alternative might be to do the put_page inside
> do_prot_none_numa(). That would be analogous to do_wp_page
> disposing of the old page for the caller.
It'd have to be inside migrate_misplaced_page(), can't do before
isolate_lru_page() or the page might disappear. Doing it after is
(obviously) too late.
> I am not real happy about NUMA migration introducing its own
> migration mode...
You didn't seem to mind too much earlier, but I can remove it if you
want.
next prev parent reply other threads:[~2012-10-19 17:54 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-19 15:53 question on NUMA page migration Rik van Riel
2012-10-19 15:53 ` Rik van Riel
2012-10-19 16:39 ` Peter Zijlstra
2012-10-19 16:39 ` Peter Zijlstra
2012-10-19 17:13 ` Rik van Riel
2012-10-19 17:13 ` Rik van Riel
2012-10-19 17:53 ` Peter Zijlstra [this message]
2012-10-19 17:53 ` Peter Zijlstra
2012-10-19 18:33 ` Rik van Riel
2012-10-19 18:33 ` Rik van Riel
2012-10-20 1:23 ` Ingo Molnar
2012-10-20 1:23 ` Ingo Molnar
2012-10-20 16:02 ` Rik van Riel
2012-10-20 16:02 ` Rik van Riel
2012-10-21 12:30 ` Ingo Molnar
2012-10-21 12:30 ` Ingo Molnar
2012-10-21 2:39 ` Ni zhan Chen
2012-10-21 2:39 ` Ni zhan Chen
2012-10-21 2:40 ` Rik van Riel
2012-10-21 2:40 ` Rik van Riel
2012-10-21 12:31 ` Ingo Molnar
2012-10-21 12:31 ` Ingo Molnar
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