Subject: Re: [PATCHv2] vhost-net: utilize PUBLISH_USED_IDX feature

From: Avi Kivity <[email-masked]>
Date: Wed, 19 May 2010 19:15:09 +0300

On 05/18/2010 08:47 PM, Avi Kivity wrote:
> On 05/18/2010 05:21 AM, Michael S. Tsirkin wrote:
>> With PUBLISH_USED_IDX, guest tells us which used entries
>> it has consumed. This can be used to reduce the number
>> of interrupts: after we write a used entry, if the guest has not yet
>> consumed the previous entry, or if the guest has already consumed the
>> new entry, we do not need to interrupt.
>> This imporves bandwidth by 30% under some workflows.
>
> Seems to be missing the cacheline alignment.
>
> Rusty's clarification did not satisfy me, I think it's needed.
>

Oh, and this should definitely follow the patch to the virtio spec, not 
precede it.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.