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Date: Sat, 8 Dec 2001 03:10:40 +0100
From: Jens Axboe <axboe@suse.de>
To: Marvin Justice <mjustice@austin.rr.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org
Subject: Re: highmem question
Message-ID: <20011208021040.GE32569@suse.de>
In-Reply-To: <Pine.LNX.4.30.0112071404280.29154-100000@mustard.heime.net> <01120719534703.00764@bozo> <20011208015446.GC32569@suse.de> <01120720102404.00764@bozo>
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On Fri, Dec 07 2001, Marvin Justice wrote:
> 
> > That's because of highmem page bouncing when doing I/O. There is indeed
> > a solution for this -- 2.5 or 2.4 + block-highmem-all patches will
> > happily do I/O directly to any page in your system as long as your
> > hardware supports it. I'm sure we're beating w2k with that enabled :-)
> 
> Will your patch lead to better performance than the CONFIGH_HIGHMEM=n case? 

No, it only makes sure that we do not take a hit with HIGHMEM enabled
for I/O.

> Unfortunately, W2K with any amount of memory beat Linux with no highmem (see 
> http://www.uwsg.indiana.edu/hypermail/linux/kernel/0110.3/0375.html ) so my 
> PHB decided to hold off on Linux for now.

Hmm I see, we can do better. With the patch you should do decently at
least with 2.4 too with 2gb of ram.

-- 
Jens Axboe

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