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From: Daniel Phillips <phillips@bonn-fries.net>
To: Andrea Arcangeli <andrea@suse.de>, Bill Davidsen <davidsen@tmr.com>
Subject: Re: 2.4.19pre1aa1
Date: Sun, 3 Mar 2002 22:38:34 +0100
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Cc: Mike Fedyk <mfedyk@matchmail.com>, linux-kernel@vger.kernel.org
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On March 2, 2002 03:06 am, Andrea Arcangeli wrote:
> On Thu, Feb 28, 2002 at 10:26:48PM -0500, Bill Davidsen wrote:
> > rather than patches. But there are a lot more small machines (which I feel
> > are better served by rmap) than large. I would like to leave the jury out
> 
> I think there's quite some confusion going on from the rmap users, let's
> clarify the facts.
> 
> The rmap design in the VM is all about decreasing the complexity of
> swap_out on the huge boxes (so it's all about saving CPU), by slowing
> down a big lots of fast common paths like page faults and by paying with
> some memory too. See the lmbench numbers posted by Randy after applying
> rmap to see what I mean.

Do you know any reason why rmap must slow down the page fault fast, or are
you just thinking about Rik's current implementation?  Yes, rmap has to add
a pte_chain entry there, but it can be a direct pointer in the unshared case
and the spinlock looks like it can be avoided in the common case as well.

-- 
Daniel
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