linux-kernel - Re: [PATCH net-next 3/3] vhost

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Message-ID: <20151201163939-mutt-send-email-mst@redhat.com>
Date:	Tue, 1 Dec 2015 16:43:05 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Jason Wang <jasowang@...hat.com>
Cc:	kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 3/3] vhost_net: basic polling support

On Tue, Dec 01, 2015 at 01:17:49PM +0800, Jason Wang wrote:
> 
> 
> On 11/30/2015 06:44 PM, Michael S. Tsirkin wrote:
> > On Wed, Nov 25, 2015 at 03:11:29PM +0800, Jason Wang wrote:
> >> > This patch tries to poll for new added tx buffer or socket receive
> >> > queue for a while at the end of tx/rx processing. The maximum time
> >> > spent on polling were specified through a new kind of vring ioctl.
> >> > 
> >> > Signed-off-by: Jason Wang <jasowang@...hat.com>
> > One further enhancement would be to actually poll
> > the underlying device. This should be reasonably
> > straight-forward with macvtap (especially in the
> > passthrough mode).
> >
> >
> 
> Yes, it is. I have some patches to do this by replacing
> skb_queue_empty() with sk_busy_loop() but for tap.

We probably don't want to do this unconditionally, though.

> Tests does not show
> any improvement but some regression.

Did you add code to call sk_mark_napi_id on tap then?
sk_busy_loop won't do anything useful without.

>  Maybe it's better to test macvtap.

Same thing ...

-- 
MST
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