linux-kernel - [PATCH v4 net-next 0/4] net: low latency Ethernet device polling

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Date:	Tue, 21 May 2013 17:26:41 +0300
From:	Eliezer Tamir <eliezer.tamir@...ux.intel.com>
To:	Dave Miller <davem@...emloft.net>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	Don Skidmore <donald.c.skidmore@...el.com>,
	e1000-devel@...ts.sourceforge.net,
	Willem de Bruijn <willemb@...gle.com>,
	Andi Kleen <andi@...stfloor.org>, HPA <hpa@...or.com>,
	Or Gerlitz <or.gerlitz@...il.com>,
	Eilon Greenstien <eilong@...adcom.com>,
	Eliezer Tamir <eliezer@...ir.org.il>
Subject: [PATCH v4 net-next 0/4] net: low latency Ethernet device polling

Hello Dave,

I believe that I addressed the issues that were raised.
Please look and see if you have more comments.

Thank you all for your input.

To prevent the use of a stale napi pointer, I implemented a global id
that should be incremented whenever a napi is freed.
I used the free space in skb's second bitfield (7 bits) since I did not
want to increase the size of the structure. In an earlier attempt to do
this I chopped the global id to seven bits but in testing, this would
crash on the wrap-around. 
Now if the seven bits that are in the skb match the global id, 
we save the un-chopped id in the socket.
(This removes the module parameter and the limit on unloading.)


is this how you prefer the change log?

change log
v4
- removed separate config option for TCP busy-polling as suggested Eric Dumazet.
- added linux mib counter for packets received through the low latency path.
- re-allow module unloading, remove module param, use a global generation id
  instead to prevent the use of a stale napi pointer, as suggested
  by Eric Dumazet
- updated Documentation/networking/ip-sysctl.txt text

v3
- coding style changes suggested by Dave Miller

v2
- the sysctl knob is now in microseconds. The default value is now 0 (off).
- for now the code depends at configure time on CONFIG_I86_TSC 
- the napi reference in struct skb is now a union with the dma cookie
  since the former is only used on RX and the latter on TX,
  as suggested by Eric Dumazet.
- we do a better job at honoring non-blocking operations.
- removed busy-polling support for tcp_read_sock()
- remove dynamic disabling of GRO
- coding style fixes
- disallow unloading the device module after the feature has been used

Thanks,
Eliezer
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