lkml.org 
[lkml]   [2011]   [Jun]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH RFC 2/3] virtio_net: fix tx capacity checks using new API
Date
On Wed, 1 Jun 2011 12:49:54 +0300, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> In the (rare) case where new descriptors are used
> while virtio_net enables vq callback for the TX vq,
> virtio_net uses the number of sg entries in the skb it frees to
> calculate how many descriptors in the ring have just been made
> available. But this value is an overestimate: with indirect buffers
> each skb only uses one descriptor entry, meaning we may wake the queue
> only to find we still can't transmit anything.

This is a bit misleading.

The value is an overestimate, but so is the requirement for
2+MAX_SKB_FRAGS, *unless* we suddenly drop into direct mode due to OOM.

Thanks,
Rusty.


\
 
 \ /
  Last update: 2011-06-02 05:59    [W:0.162 / U:2.412 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site