linux-kernel - Re: [PATCH net-next] tuntap: introduce tx skb ring

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Message-ID: <20160518101631.368e3447@redhat.com>
Date:	Wed, 18 May 2016 10:16:31 +0200
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Jason Wang <jasowang@...hat.com>
Cc:	brouer@...hat.com, "Michael S. Tsirkin" <mst@...hat.com>,
	davem@...emloft.net, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] tuntap: introduce tx skb ring


On Tue, 17 May 2016 09:38:37 +0800 Jason Wang <jasowang@...hat.com> wrote:

> >> And if tx_queue_length is not power of 2,
> >> we probably need modulus to calculate the capacity.  
> > Is that really that important for speed?  
> 
> Not sure, I can test.

In my experience, yes, adding a modulus does affect performance.

> > If yes, round it up to next power of two.  
> 
> Right, this sounds a good solution.

Good idea.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer