netdev - RE: [PATCH net-next,1/1] hv_netvsc: call dump_rndis

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Date:	Tue, 21 Apr 2015 22:14:14 +0000
From:	Simon Xiao <sixiao@...rosoft.com>
To:	David Miller <davem@...emloft.net>
CC:	KY Srinivasan <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH net-next,1/1] hv_netvsc: call dump_rndis_message() only in
 netvsc debug mode


> -----Original Message-----
> From: David Miller [mailto:davem@...emloft.net]
> Sent: Tuesday, April 21, 2015 2:49 PM
> To: Simon Xiao
> Cc: KY Srinivasan; Haiyang Zhang; devel@...uxdriverproject.org;
> netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH net-next,1/1] hv_netvsc: call dump_rndis_message() only in
> netvsc debug mode
> 
> From: sixiao@...rosoft.com
> Date: Tue, 21 Apr 2015 15:58:05 -0700
> 
> > From: Simon Xiao <sixiao@...rosoft.com>
> >
> > Signed-off-by: Simon Xiao <sixiao@...rosoft.com>
> > Reviewed-by: K. Y. Srinivasan <kys@...rosoft.com>
> > Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>
> 
> I just gave you feedback on this patch in response to your original submission,
> do not ignore it.

Thanks for your feedback, David.

In current netvsc driver, for each packet received, it will call dump_rndis_message() 
to try to dump the rndis packet information by netdev_dbg(). 
In non-debug mode, dump_rndis_message() will not dump anything 
but it still initialize some local variables and process the switch logic in the function 
of dump_rndis_message(), which is unnecessary, especially in high network throughput situation.

My change is to have a run-time config flag to control the execution of dump_rndis_message() 
and avoid above unnecessary cost in non-debug mode.
In the default case, it will be non-debug mode,
 and rndis_filter_receive() will not call dump_rndis_message() 
which saves the above extra cost for each packet received.
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