Re: [PATCH net-next 1/2] vhost_net: mitigate page reference counting during page frag refill

David Miller
2018-11-17T20:01:05Z

From: Jason Wang <jasowang@redhat.com>
Date: Thu, 15 Nov 2018 17:43:09 +0800

> We do a get_page() which involves a atomic operation. This patch tries
> to mitigate a per packet atomic operation by maintaining a reference
> bias which is initially USHRT_MAX. Each time a page is got, instead of
> calling get_page() we decrease the bias and when we find it's time to
> use a new page we will decrease the bias at one time through
> __page_cache_drain_cache().
>
> Testpmd(virtio_user + vhost_net) + XDP_DROP on TAP shows about 1.6%
> improvement.
>
> Before: 4.63Mpps
> After: 4.71Mpps
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Applied.