linux-kernel - Re: [RFC PATCH 0/3] generic hypercall support

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Date:	Thu, 07 May 2009 13:03:45 -0400
From:	Gregory Haskins <ghaskins@...ell.com>
To:	Chris Wright <chrisw@...s-sol.org>
CC:	Gregory Haskins <gregory.haskins@...il.com>,
	Avi Kivity <avi@...hat.com>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, Anthony Liguori <anthony@...emonkey.ws>
Subject: Re: [RFC PATCH 0/3] generic hypercall support

Chris Wright wrote:
> * Gregory Haskins (ghaskins@...ell.com) wrote:
>   
>> Chris Wright wrote:
>>     
>>> VF drivers can also have this issue (and typically use mmio).
>>> I at least have a better idea what your proposal is, thanks for
>>> explanation.  Are you able to demonstrate concrete benefit with it yet
>>> (improved latency numbers for example)?
>>>       
>> I had a test-harness/numbers for this kind of thing, but its a bit
>> crufty since its from ~1.5 years ago.  I will dig it up, update it, and
>> generate/post new numbers.
>>     
>
> That would be useful, because I keep coming back to pio and shared
> page(s) when think of why not to do this.  Seems I'm not alone in that.
>
> thanks,
> -chris
>   

I completed the resurrection of the test and wrote up a little wiki on
the subject, which you can find here:

http://developer.novell.com/wiki/index.php/WhyHypercalls

Hopefully this answers Chris' "show me the numbers" and Anthony's "Why
reinvent the wheel?" questions.

I will include this information when I publish the updated v2 series
with the s/hypercall/dynhc changes.

Let me know if you have any questions.

-Greg


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