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Date: Sat, 2 Feb 2002 16:38:51 +0100 (CET)
From: Roy Sigurd Karlsbakk <roy@karlsbakk.net>
To: Roger Larsson <roger.larsson@norran.net>
cc: Jens Axboe <axboe@suse.de>, Andrew Morton <akpm@zip.com.au>,
        <linux-kernel@vger.kernel.org>, Tux mailing list <tux-list@redhat.com>
Subject: Re: Errors in the VM - detailed (or is it Tux? or rmap? or those
 together...)
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> I have reread the first mail in this series - I would say that Bug#2 is much
> worse than Bug#1. This since Bug#1 is "only" a performance problem,
> but Bug#2 is about correctness...
>
> Are you 100% sure that tux works with rmap?

Of course not. How can I be sure???

> I would suggest testing the simplest possible case.
> * Standard kernel
> * concurrent dd:s

Won't work. Then all I get is (ref prob #1) good throughput until RAMx2
bytes is read from disk. Then it all falls down to ~1MB/s. See
http://karlsbakk.net/dev/kernel/vm-fsckup.txt for more details.

> What can your problem be:
> * something to do with the VM - but the problem is in several different VMs...
> * something to do with read ahead? you got some patch suggestions -
>   please use them on a standard kernel, not rmap (for now...)

Then fix the problem rmap11c fixed. I first need that fixed before being
able to do any further testing!

roy

--
Roy Sigurd Karlsbakk, MCSE, MCNE, CLS, LCA

Computers are like air conditioners.
They stop working when you open Windows.

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