Re: [PATCH net-next 2/2] virtio-net: fix the XDP truesize calculation for mergeable buffers

[Jason Wang]

On 2020/5/6 äå3:37, Michael S. Tsirkin wrote:
> On Wed, May 06, 2020 at 02:16:33PM +0800, Jason Wang wrote:
> > We should not exclude headroom and tailroom when XDP is set. So this
> > patch fixes this by initializing the truesize from PAGE_SIZE when XDP
> > is set.
> >
> > Cc: Jesper Dangaard Brouer<brouer@xxxxxxxxxx>
> > Signed-off-by: Jason Wang<jasowang@xxxxxxxxxx>
> Seems too aggressive, we do not use up the whole page for the size.

For XDP yes, we do:

static unsigned int get_mergeable_buf_len(struct receive_queue *rq,
ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ Â struct ewma_pkt_len *avg_pkt_len,
ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂ Â unsigned int room)
{
ÂÂÂ const size_t hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
ÂÂÂ unsigned int len;

ÂÂÂ if (room)
ÂÂÂ ÂÂÂ return PAGE_SIZE - room;

...

Thanks