From: Andi Kleen <ak@suse.de>
Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg)
To: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/2] msi: Invert the sense of the MSI enables.
Date: Fri, 25 May 2007 07:51:45 +0200
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Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
       Greg Kroah-Hartman <gregkh@suse.de>,
       Jay Cliburn <jacliburn@bellsouth.net>,
       Grzegorz Krzystek <ninex@ninex.eu.org>, ninex@o2.pl,
       linux-kernel@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz,
       Michael Ellerman <michael@ellerman.id.au>,
       David Miller <davem@davemloft.net>, Tony Luck <tony.luck@intel.com>,
       Linus Torvalds <torvalds@linux-foundation.org>
References: <200705122146.l4CLkH6q012322@fire-2.osdl.org> <m1veehcz7m.fsf_-_@ebiederm.dsl.xmission.com> <20070524213157.1d39458f.akpm@linux-foundation.org>
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> Do we have a feel for how much performace we're losing on those 
> systems which _could_ do MSI, but which will end up defaulting
> to not using it?

At least on 10GB ethernet it is a significant difference; you usually
cannot go anywhere near line speed without MSI

I suspect it is visible on high performance / multiple GB NICs too.

-Andi
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