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Re: [Xen-devel] 46% performance drop with change in glibc

To: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] 46% performance drop with change in glibc
From: Andrew Theurer <habanero@xxxxxxxxxx>
Date: Tue, 08 Nov 2005 07:05:49 -0600
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Ulrich Drepper <drepper@xxxxxxxxxx>, Robert Read <robert@xxxxxxxxxxxxx>
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Ian Pratt wrote:

The crippled ABI is supported by the code in /lib/i686/nosegneg. This code is *automatically* used if the kernel is
compiled to match
the glibc version.  This happens using the

linux-2.6-xen-vdso-note.patch

I believe we have this patch in the xen repo, but I haven't ever verified whether the right thing happens under FC4.

I am not seeing this patch in ./patches/linux-2.6.12 directory. Is it somewhere else?


It should be in the main tree. The appended patch was included some time
ago, but I've never tested it to see whether it works since I don't
generally run bleeding edge Fedora.

Is there some piece of the patch missing?

No, it's all there. Only part I needed was the change to ld.so.conf. So, anyone with FC4, you might want to make sure you have the entry "hwcap 0 nosegneg". It looks like the performance regression has disappeared now. Thanks all for you help.

-Andrew


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