lkml.org 
[lkml]   [2010]   [May]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCHv2-RFC 0/2] virtio: put last seen used index into ring itself
On 05/30/10 13:22, Michael S. Tsirkin wrote:
> On Fri, May 28, 2010 at 11:56:54AM +0200, Jes Sorensen wrote:
>> It looks pretty good to me, however one thing I have been thinking of
>> while reading through it:
>>
>> Rather than storing a pointer within the ring struct, pointing into a
>> position within the same struct. How about storing a byte offset instead
>> and using a cast to get to the pointer position? That would avoid the
>> pointer dereference, which is less effective cache wise and harder for
>> the CPU to predict.
>>
>> Not sure whether it really matters performance wise, just a thought.
>
> I think this won't work: when PUBLUSH_USED_IDX is negotiated,
> the pointer is to within the ring.

Hmmm shame, it would be a nice optimization.

Maybe it's time to introduce the v2 ring format, rather than having
adding more kludges to the existing one?

Cheers,
Jes


\
 
 \ /
  Last update: 2010-05-31 09:39    [W:0.163 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site