netdev - RE: [net-next] bnx2x: Handle Rx and Tx together in NAPI

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Date:	Mon, 16 Nov 2009 16:02:04 +0530
From:	"Kumar Gopalpet-B05799" <B05799@...escale.com>
To:	"David Miller" <davem@...emloft.net>, <vladz@...adcom.com>
Cc:	<netdev@...r.kernel.org>, <eilong@...adcom.com>
Subject: RE: [net-next] bnx2x: Handle Rx and Tx together in NAPI

 

>From: "Vladislav Zolotarov" <vladz@...adcom.com>
>Date: Mon, 16 Nov 2009 12:01:09 +0200
>
>>   - Limit Tx work done in one iteration by the same number 
>of packets 
>> as Rx in order to ensure both fair work load balancing relatively to 
>> other devices scheduled for NAPI on the local CPU and sane Tx/Rx skb 
>> resource management from single QP perspective.
>
>You should not do this.

Can we actually introduce NAPI mechanism for cleaning TX ring ??
 
>RX is several orders of magnitude more work than TX is.  TX 
>therefore should not be charged against the NAPI polling quota.
>
>Don't try to be different from other drivers unless you have 
>detailed performance numbers from various situations (local 
>TCP flows _and_
>routing) to justify it. :-)
>
I tried (I am talking about gianfar driver) to introduce napi for
cleaning tx ring (similar to rx napi mechanism ) and found that it
actually improves performance for bi-directioanl flow on an SMP system
(performance is abt 1.6 times). 
If introducing napi mechansim for tx is logical then I will send out an
RFC patch
>All NAPI drivers ignore TX work when considering NAPI polling 
>quotas and you should too :-)
>--


--

Thanks
Sandeep
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