linux-kernel - Re: system call time increase when turning on CONFIG

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Message-Id: <1173312124.8383.35.camel@localhost.localdomain>
Date:	Wed, 07 Mar 2007 16:02:04 -0800
From:	Tim Chen <tim.c.chen@...ux.intel.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>, zach@...are.com
Cc:	linux-kernel@...r.kernel.org,
	Virtualization Mailing List <virtualization@...ts.osdl.org>
Subject: Re: system call time increase when turning on CONFIG_PARAVIRT

On Fri, 2007-03-02 at 16:16 -0800, Jeremy Fitzhardinge wrote:

> 
> Yes, the intent is that running a CONFIG_PARAVIRT kernel on native
> hardware will have negligible performance hit compared to running a
> non-paravirt kernel.
> 
>     J

It turned out that VDSO was turned off by CONFIG_PARAVIRT option,
causing the system call to use inefficient int 0x80 which led to the
increase system_call time I was seeing.  I noted that Ingo has caught
this problem and proposed a patch to correct this issue in another mail
thread.

Tim
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