Message-ID: <45BE9FE8.4080603@mbligh.org>
Date: Mon, 29 Jan 2007 17:31:20 -0800
From: "Martin J. Bligh" <mbligh@mbligh.org>
User-Agent: Thunderbird 1.5.0.5 (X11/20060728)
MIME-Version: 1.0
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
References: <1169993494.10987.23.camel@lappy>	 <20070128142925.df2f4dce.akpm@osdl.org> <1170063848.6189.121.camel@twins>
In-Reply-To: <1170063848.6189.121.camel@twins>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 971
Lines: 27

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.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/