linux-kernel - RE: [v1 0/6] *** nps

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Message-ID: <DB4PR02MB2725A45B664C42E3AB7B98ED6780@DB4PR02MB272.eurprd02.prod.outlook.com>
Date:	Tue, 18 Aug 2015 05:04:20 +0000
From:	Noam Camus <noamc@...hip.com>
To:	David Miller <davem@...emloft.net>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"Alexey.Brodkin@...opsys.com" <Alexey.Brodkin@...opsys.com>,
	"vgupta@...opsys.com" <vgupta@...opsys.com>,
	Tal Zilcer <talz@...hip.com>
Subject: RE: [v1 0/6] *** nps_enet fixups ***

From: David Miller [mailto:davem@...emloft.net] 
Sent: Monday, August 17, 2015 8:36 PM


> You should not move TX completion out of NAPI handling, NAPI poll is exactly where it belongs.
>
> If you handle it in hardware interrupt context you have to use
> dev_kfree_skb_irq() which defers the operation to software interrupt context anyways and is thus expensive.

> Whereas if you keep TX completion in your NAPI handler the kfree is handled synchronously and efficiently, as well as making SKB's potentially available for RX reclaim.

I followed "Hardware Architecture" section from:
http://www.linuxfoundation.org/collaborate/workgroups/networking/napi
and came up with "reduce processing latency" idea.

Anyway, I will restore TX completion back to NAPI poll.

> I'm not applying this series, you are doing with TX handling exactly what we tell people not to do.

I will come up with revised series in v2.

Noam
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