From: Andi Kleen <andi@firstfloor.org>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Rafael Aquini <aquini@redhat.com>,
linux-mm@kvack.org, Rik van Riel <riel@redhat.com>,
Andi Kleen <andi@firstfloor.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 1/4] mm: introduce compaction and migration for virtio ballooned pages
Date: Tue, 26 Jun 2012 18:52:58 +0200 [thread overview]
Message-ID: <20120626165258.GY11413@one.firstfloor.org> (raw)
In-Reply-To: <20120626101729.GF8103@csn.ul.ie>
>
> What shocked me actually is that VM_BUG_ON code is executed on
> !CONFIG_DEBUG_VM builds and has been since 2.6.36 due to commit [4e60c86bd:
> gcc-4.6: mm: fix unused but set warnings]. I thought the whole point of
> VM_BUG_ON was to avoid expensive and usually unnecessary checks. Andi,
> was this deliberate?
The idea was that the compiler optimizes it away anyways.
I'm not fully sure what putback_balloon_page does, but if it just tests
a bit (without non variable test_bit) it should be ok.
-Andi
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <andi@firstfloor.org>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Rafael Aquini <aquini@redhat.com>,
linux-mm@kvack.org, Rik van Riel <riel@redhat.com>,
Andi Kleen <andi@firstfloor.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 1/4] mm: introduce compaction and migration for virtio ballooned pages
Date: Tue, 26 Jun 2012 18:52:58 +0200 [thread overview]
Message-ID: <20120626165258.GY11413@one.firstfloor.org> (raw)
In-Reply-To: <20120626101729.GF8103@csn.ul.ie>
>
> What shocked me actually is that VM_BUG_ON code is executed on
> !CONFIG_DEBUG_VM builds and has been since 2.6.36 due to commit [4e60c86bd:
> gcc-4.6: mm: fix unused but set warnings]. I thought the whole point of
> VM_BUG_ON was to avoid expensive and usually unnecessary checks. Andi,
> was this deliberate?
The idea was that the compiler optimizes it away anyways.
I'm not fully sure what putback_balloon_page does, but if it just tests
a bit (without non variable test_bit) it should be ok.
-Andi
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next prev parent reply other threads:[~2012-06-26 16:53 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-25 23:25 [PATCH 0/4] make balloon pages movable by compaction Rafael Aquini
2012-06-25 23:25 ` Rafael Aquini
2012-06-25 23:25 ` [PATCH 1/4] mm: introduce compaction and migration for virtio ballooned pages Rafael Aquini
2012-06-25 23:25 ` Rafael Aquini
2012-06-25 23:25 ` Rafael Aquini
2012-06-25 23:31 ` Konrad Rzeszutek Wilk
2012-06-25 23:31 ` Konrad Rzeszutek Wilk
2012-06-25 23:31 ` Konrad Rzeszutek Wilk
2012-06-25 23:57 ` Rafael Aquini
2012-06-25 23:57 ` Rafael Aquini
2012-06-25 23:57 ` Rafael Aquini
2012-06-26 10:17 ` Mel Gorman
2012-06-26 10:17 ` Mel Gorman
2012-06-26 16:52 ` Andi Kleen [this message]
2012-06-26 16:52 ` Andi Kleen
2012-06-26 16:54 ` Andi Kleen
2012-06-26 16:54 ` Andi Kleen
2012-06-26 16:54 ` Andi Kleen
2012-06-26 20:15 ` Mel Gorman
2012-06-26 20:15 ` Mel Gorman
2012-06-26 20:34 ` Andi Kleen
2012-06-26 20:34 ` Andi Kleen
2012-06-26 20:34 ` Andi Kleen
2012-06-27 9:42 ` Mel Gorman
2012-06-27 9:42 ` Mel Gorman
2012-06-27 9:42 ` Mel Gorman
2012-06-26 20:15 ` Mel Gorman
2012-06-26 16:52 ` Andi Kleen
2012-06-26 22:01 ` Rafael Aquini
2012-06-26 22:01 ` Rafael Aquini
2012-06-26 22:01 ` Rafael Aquini
2012-06-26 10:17 ` Mel Gorman
2012-06-26 13:17 ` Rik van Riel
2012-06-26 13:17 ` Rik van Riel
2012-06-26 13:17 ` Rik van Riel
2012-06-26 13:20 ` Mel Gorman
2012-06-26 13:20 ` Mel Gorman
2012-06-26 13:20 ` Mel Gorman
2012-06-26 23:57 ` Konrad Rzeszutek Wilk
2012-06-26 23:57 ` Konrad Rzeszutek Wilk
2012-06-27 15:17 ` Rafael Aquini
2012-06-27 15:17 ` Rafael Aquini
2012-06-27 15:30 ` Konrad Rzeszutek Wilk
2012-06-27 15:30 ` Konrad Rzeszutek Wilk
2012-06-27 15:30 ` Konrad Rzeszutek Wilk
2012-06-27 15:17 ` Rafael Aquini
2012-06-26 23:57 ` Konrad Rzeszutek Wilk
2012-06-25 23:25 ` [PATCH 2/4] virtio_balloon: handle concurrent accesses to virtio_balloon struct elements Rafael Aquini
2012-06-25 23:25 ` Rafael Aquini
2012-06-25 23:25 ` Rafael Aquini
2012-06-25 23:25 ` [PATCH 3/4] virtio_balloon: introduce migration primitives to balloon pages Rafael Aquini
2012-06-25 23:25 ` Rafael Aquini
2012-06-25 23:25 ` Rafael Aquini
2012-06-25 23:25 ` [PATCH 4/4] mm: add vm event counters for balloon pages compaction Rafael Aquini
2012-06-25 23:25 ` Rafael Aquini
2012-06-25 23:25 ` Rafael Aquini
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