linux-kernel - Re: i686 quirk for AMD Geode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 11 Nov 2009 11:54:46 +0100
From:	Bernd Petrovitsch <bernd@...mix.at>
To:	Pavel Machek <pavel@....cz>
Cc:	Willy Tarreau <w@....eu>, "H. Peter Anvin" <hpa@...or.com>,
	Avi Kivity <avi@...hat.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Matteo Croce <technoboy85@...il.com>,
	Sven-Haegar Koch <haegar@...net.de>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: i686 quirk for AMD Geode

Hi!

On Tue, 2009-11-10 at 21:54 +0100, Pavel Machek wrote:
[...]
> > CMOV/NOPL are rarely used, thus have no reason to cause a massive
> > performance drop, but are frequent enough (at least cmov) for almost
> 
> *One* CMOV in the inner loop will make your performance go down 20x.
But it runs.
The pragmatic side is:
If people notices the performance drop, it would be good to have
something in syslog and/or dmesg and/or /proc and/or sysfs
If people do not notice the performance drop, who cares?

	Bernd
-- 
Firmix Software GmbH                   http://www.firmix.at/
mobil: +43 664 4416156                 fax: +43 1 7890849-55
          Embedded Linux Development and Services


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/