netdev - RE: [PATCH 2.6.34-rc6] net: Improve ks8851 snl transmit performance

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Message-ID: <14385191E87B904DBD836449AA30269D6DF528@MORGANITE.micrel.com>
Date:	Mon, 24 May 2010 10:28:40 -0700
From:	"Ha, Tristram" <Tristram.Ha@...rel.Com>
To:	"David Miller" <davem@...emloft.net>
Cc:	<ben@...tec.co.uk>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <x0066660@...com>, <s-jan@...com>
Subject: RE: [PATCH 2.6.34-rc6] net: Improve ks8851 snl transmit performance

David Miller wrote:
> From: "Ha, Tristram" <Tristram.Ha@...rel.Com>
> Date: Thu, 6 May 2010 15:50:27 -0700
> 
>> From: Tristram Ha <Tristram.Ha@...rel.com>
>> 
>> Under heavy transmission the driver will put 4 1514-byte packets in
>> queue and stop the device transmit queue.  Only the last packet
>> triggers the transmit done interrupt and wakes up the device transmit
>> queue.  That means a bit of time is wasted when the CPU cannot send
>> any more packet.
>> 
>> The new implementation triggers the transmit interrupt when the
>> transmit buffer left is less than 3 packets.  The maximum transmit
>> buffer size is 6144 bytes.  This allows the device transmit queue to
>> be restarted sooner so that CPU can send more packets.
>> 
>> For TCP receiving it also has the benefit of not triggering any
transmit interrupt at all.
>> 
>> There is a driver option no_tx_opt so that the driver can revert to
>> original implementation.  This allows user to verify if the transmit
>> performance actually improves.
>> 
>> Signed-off-by: Tristram Ha <Tristram.Ha@...rel.com>
> 
> First, if you want to post patches you have to format them properly as
ascii text with no longer
> than 80 column lines in your commit message. 
> I really don't want to hear about your email client being a reason you
can't do this properly :-)
> 
> Second, I don't think you can use the skb->ip_summed for this hacked
state tracking you are
> using.  The packet might be shared with other entities, and therefore
if you change the field it
> won't be correct for them any more.  

Sorry about the patch description.  I must have forgotten the rules.

As the socket buffer is accepted by the lowest level network driver and
reaches the end of its life, I think using one of its variables
temporarily does not cause any harm.
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