Date: Thu, 8 Apr 2004 01:18:06 +0200
From: Andrea Arcangeli <andrea@suse.de>
To: "Martin J. Bligh" <mbligh@aracnet.com>
Cc: Ingo Molnar <mingo@elte.hu>, Eric Whiting <ewhiting@amis.com>,
       akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: -mmX 4G patches feedback [numbers: how much performance impact]
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On Wed, Apr 07, 2004 at 04:21:44PM -0700, Martin J. Bligh wrote:
> Speaking of which, pte_highmem is stinking expensive itself. There's
> probably a large class of workloads that'd work with out pte_highmem
> if we had 4/4 split (or shared pagetables. Grrr ;-))

hey, I can add a sysctl in 5 minutes to disable pte_highmem at runtime,
why do you think it's expensive, it should be not, it's all atomic kmaps
only doing invlpg. The few workloads trashing on the ptes manipulation
needs pte_highmem anyways. If I thought it was expensive for any common
load the sysctl would be already there.
-
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