netdev - Re: [PATCH net-next-2.6] net: sock_def_readable() and friends RCU conversion

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Date:	Fri, 30 Apr 2010 09:55:34 -0400
From:	Brian Bloniarz <bmb@...enacr.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	hadi@...erus.ca, Changli Gao <xiaosuo@...il.com>,
	David Miller <davem@...emloft.net>, therbert@...gle.com,
	shemminger@...tta.com, netdev@...r.kernel.org,
	Eilon Greenstein <eilong@...adcom.com>
Subject: Re: [PATCH net-next-2.6] net: sock_def_readable() and friends RCU
 conversion

Eric Dumazet wrote:
> Here is last 'patch of the day' for me ;)
> Next one will be able to coalesce wakeup calls (they'll be delayed at
> the end of net_rx_action(), like a patch I did last year to help
> multicast reception)
>
> vger seems to be down, I suspect I'll have to resend it later.
>
> [PATCH net-next-2.6] net: sock_def_readable() and friends RCU conversion
>
> sk_callback_lock rwlock actually protects sk->sk_sleep pointer, so we
> need two atomic operations (and associated dirtying) per incoming
> packet.
>   

This patch boots for me, I haven't noticed any strangeness yet.

I ran a few benchmarks (the multicast fan-out mcasttest.c
from last year, a few other things we have lying around).
I think I see a modest improvement from this and your other
2 packets. Presumably the big wins are where multiple cores
perform bh for the same socket, that's not the case in
these benchmarks. If it's appropriate:

Tested-by: Brian Bloniarz <bmb@...enacr.com>

> Next one will be able to coalesce wakeup calls (they'll be delayed at
> the end of net_rx_action(), like a patch I did last year to help
> multicast reception)

Keep em coming :)
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