netdev - Re: tun: Only wake up writers

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Message-Id: <20090603.214610.86822955.davem@davemloft.net>
Date:	Wed, 03 Jun 2009 21:46:10 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	herbert@...dor.apana.org.au
Cc:	netdev@...r.kernel.org
Subject: Re: tun: Only wake up writers

From: Herbert Xu <herbert@...dor.apana.org.au>
Date: Wed, 3 Jun 2009 22:36:55 +1000

> tun: Only wake up writers
> 
> When I added socket accounting to tun I inadvertently introduced
> spurious wake-up events that kills qemu performance.  The problem
> occurs when qemu polls on the tun fd for read, and then transmits
> packets.  For each packet transmitted, we will wake up qemu even
> if it only cares about read events.
> 
> Now this affects all sockets, but it is only a new problem for
> tun.  So this patch tries to fix it for tun first and we can then
> look at the problem in general.
>  
> Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

Applied to net-next-2.6, thanks Herbert!
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