netdev - Re: Possible regression: Packet drops during iptables calls

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Date:	Thu, 16 Dec 2010 15:29:35 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jesper Dangaard Brouer <hawk@...x.dk>
Cc:	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Steven Rostedt <srostedt@...hat.com>,
	Alexander Duyck <alexander.h.duyck@...el.com>,
	Stephen Hemminger <shemminger@...tta.com>,
	netfilter-devel <netfilter-devel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@...el.com>
Subject: Re: Possible regression: Packet drops during iptables calls

Le jeudi 16 décembre 2010 à 15:24 +0100, Jesper Dangaard Brouer a
écrit :

> In my case I think this will not help. I'll kill the cache anyways, as
> the ruleset is 19MB and my CPU cache is 8MB.
> 
> 

Yep ;)

By the way, you speak of a 'possible regression', but we always masked
BH while doing get_counters().

Only very recent kernels are masking them for each unit (cpu) of work.

There was attempt to use a lockless read for each counter (using a
seqlock), but it was not completed. I guess we could do something to
ressurect this idea.



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