From: "Martin J. Bligh" <mbligh@mbligh.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] mm: remove global locks from mm/highmem.c
Date: Mon, 29 Jan 2007 17:31:20 -0800 [thread overview]
Message-ID: <45BE9FE8.4080603@mbligh.org> (raw)
In-Reply-To: <1170063848.6189.121.camel@twins>
Peter Zijlstra wrote:
> On Sun, 2007-01-28 at 14:29 -0800, Andrew Morton wrote:
>
>> As Christoph says, it's very much preferred that code be migrated over to
>> kmap_atomic(). Partly because kmap() is deadlockable in situations where a
>> large number of threads are trying to take two kmaps at the same time and
>> we run out. This happened in the past, but incidences have gone away,
>> probably because of kmap->kmap_atomic conversions.
>
>> From which callsite have you measured problems?
>
> CONFIG_HIGHPTE code in -rt was horrid. I'll do some measurements on
> mainline.
>
CONFIG_HIGHPTE is always horrid -we've known that for years.
Don't use it.
If that's all we're fixing here, I'd be highly suspect ...
M.
WARNING: multiple messages have this Message-ID (diff)
From: "Martin J. Bligh" <mbligh@mbligh.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] mm: remove global locks from mm/highmem.c
Date: Mon, 29 Jan 2007 17:31:20 -0800 [thread overview]
Message-ID: <45BE9FE8.4080603@mbligh.org> (raw)
In-Reply-To: <1170063848.6189.121.camel@twins>
Peter Zijlstra wrote:
> On Sun, 2007-01-28 at 14:29 -0800, Andrew Morton wrote:
>
>> As Christoph says, it's very much preferred that code be migrated over to
>> kmap_atomic(). Partly because kmap() is deadlockable in situations where a
>> large number of threads are trying to take two kmaps at the same time and
>> we run out. This happened in the past, but incidences have gone away,
>> probably because of kmap->kmap_atomic conversions.
>
>> From which callsite have you measured problems?
>
> CONFIG_HIGHPTE code in -rt was horrid. I'll do some measurements on
> mainline.
>
CONFIG_HIGHPTE is always horrid -we've known that for years.
Don't use it.
If that's all we're fixing here, I'd be highly suspect ...
M.
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next prev parent reply other threads:[~2007-01-30 1:31 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-28 14:11 [PATCH] mm: remove global locks from mm/highmem.c Peter Zijlstra
2007-01-28 14:11 ` Peter Zijlstra
2007-01-28 14:49 ` Christoph Hellwig
2007-01-28 14:49 ` Christoph Hellwig
2007-01-28 15:17 ` Ingo Molnar
2007-01-28 15:17 ` Ingo Molnar
2007-01-28 15:28 ` Christoph Hellwig
2007-01-28 15:28 ` Christoph Hellwig
2007-01-28 15:48 ` Ingo Molnar
2007-01-28 15:48 ` Ingo Molnar
2007-01-28 15:54 ` Christoph Hellwig
2007-01-28 15:54 ` Christoph Hellwig
2007-01-28 18:19 ` Ingo Molnar
2007-01-28 18:19 ` Ingo Molnar
2007-01-28 22:29 ` Andrew Morton
2007-01-28 22:29 ` Andrew Morton
2007-01-29 2:52 ` Nick Piggin
2007-01-29 2:52 ` Nick Piggin
2007-01-29 9:44 ` Peter Zijlstra
2007-01-29 9:44 ` Peter Zijlstra
2007-01-30 1:31 ` Martin J. Bligh [this message]
2007-01-30 1:31 ` Martin J. Bligh
2007-01-30 1:41 ` Andrew Morton
2007-01-30 1:41 ` Andrew Morton
2007-01-30 1:49 ` Martin J. Bligh
2007-01-30 1:49 ` Martin J. Bligh
2007-01-30 2:15 ` Andrew Morton
2007-01-30 2:15 ` Andrew Morton
2007-01-31 0:44 ` David Chinner
2007-01-31 0:44 ` David Chinner
2007-01-31 1:11 ` Andrew Morton
2007-01-31 1:11 ` Andrew Morton
2007-01-31 3:22 ` David Chinner
2007-01-31 3:22 ` David Chinner
2007-02-02 12:05 ` Christoph Hellwig
2007-02-02 12:05 ` Christoph Hellwig
2007-02-02 19:24 ` Matt Mackall
2007-02-02 19:24 ` Matt Mackall
2007-02-02 23:16 ` David Chinner
2007-02-02 23:16 ` David Chinner
2007-02-02 23:14 ` David Chinner
2007-02-02 23:14 ` David Chinner
2007-01-29 19:08 ` Ingo Molnar
2007-01-29 19:08 ` Ingo Molnar
2007-01-29 19:19 ` Hugh Dickins
2007-01-29 19:19 ` Hugh Dickins
2007-01-29 19:53 ` Ingo Molnar
2007-01-29 19:53 ` Ingo Molnar
2007-01-29 20:06 ` Ingo Molnar
2007-01-29 20:06 ` Ingo Molnar
2007-01-30 2:02 ` Nick Piggin
2007-01-30 2:02 ` Nick Piggin
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