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From: Zachary Amsden <zach@vmware.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: tim.c.chen@linux.intel.com, linux-kernel@vger.kernel.org,
	Virtualization Mailing List <virtualization@lists.osdl.org>
Subject: Re: system call time increase when turning on CONFIG_PARAVIRT
Date: Fri, 02 Mar 2007 23:00:59 -0800	[thread overview]
Message-ID: <45E91D2B.9040004@vmware.com> (raw)
In-Reply-To: <45E8BE79.40200@goop.org>

Jeremy Fitzhardinge wrote:
> Tim Chen wrote:
>   
>> I also hope that the performance can be recovered as this option could
>> enabled in distributions' kernels in future.
>>     
>
> 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.
>   

We can validate that claim entirely.  The way we are proceeding, the 
native code will be inlined or direct called as much as possible.  With 
the VMI-Linux code we had earlier, this mostly created <3% overhead for 
microbenchmarks (and in some cases, we actually won over the unmodified 
native code).  For macro-benchmarks, with real-world workloads, this 
reduced to immeasurable noise, never off by more than +/- 0.5% IIRC.

I believe all of this is totally achievable.  We have the technology.  
We can rebuild it.

Zach

  reply	other threads:[~2007-03-03  7:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1172866274.4898.14.camel@localhost.localdomain>
2007-03-02 21:54 ` system call time increase when turning on CONFIG_PARAVIRT Jeremy Fitzhardinge
2007-03-02 23:11   ` Tim Chen
2007-03-03  0:16     ` Jeremy Fitzhardinge
2007-03-03  7:00       ` Zachary Amsden [this message]
2007-03-08  0:02       ` Tim Chen
2007-03-08  0:55         ` Jeremy Fitzhardinge

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