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Date: Mon, 18 Jul 2011 22:46:32 +0400
From: Vasiliy Kulikov <segoon@...nwall.com>
To: kernel-hardening@...ts.openwall.com
Subject: Re: PAX_USERCOPY testing
Hi,
On Thu, Jul 14, 2011 at 20:13 +0400, Vasiliy Kulikov wrote:
> This is a version of PAX_USERCOPY I want to send to LKML. However, the
> patch without performance testing would be incomplete. I have some
> syscalls measurements, the worst case is gethostname() with 6-7% penalty
> on x86-64 (Intel Core 2 Duo 2Ghz).
The previous benchmarks are totally wrong. I didn't disable background
daemons, which created significant error, and used on-demand CPU
governor, which finally smashed results.
Measurements with maximum governor and with minimum processes showed
great "boost":
The worst case of tiny syscalls, gethostname(), has 0,9% slowdown.
Real workflows - find /usr, git log -Sredirect, make in kernel tree,
files copying - are not affected by the feature at all (the slowdown is
so low that I cannot effectively measure it, so it is less than 0,1%).
So, I've sent RFCv2 to LKML as-is :-)
I suppose no sysctl to control the behaviour is needed - the permormance
is acceptable for real workflows IMO.
Thanks,
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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