From: Eric Dumazet <dada1@cosmosbay•com>
To: Jan Engelhardt <jengelh@medozas•de>
Cc: David Miller <davem@davemloft•net>,
graham@gmurray•org.uk, linux-kernel@vger•kernel.org,
netdev@vger•kernel.org, netfilter-devel@vger•kernel.org
Subject: Re: Regression caused by commit "netfilter: iptables: lock free counters"
Date: Sun, 05 Apr 2009 14:34:50 +0200 [thread overview]
Message-ID: <49D8A56A.8050606@cosmosbay.com> (raw)
In-Reply-To: <alpine.LSU.2.00.0904051328030.7501@fbirervta.pbzchgretzou.qr>
Jan Engelhardt a écrit :
> On Sunday 2009-04-05 12:01, Eric Dumazet wrote:
>> This could probably be solved using a single "table" containing
>> rules only, that could be shared for every cpus. Only counters
>> should be percpu. This should save a lot of ram, over previous
>> situation (2.6.29 or current one)
>
> Why would counters stay separate?
>
> I recognize all of this table copying is related to do NUMA
> optimizations, and I think I heard cache bouncing too somewhere else.
>
> [ http://marc.info/?l=netfilter-devel&m=119903624211253&w=2 ]
>
>
Not only NUMA, but SMP too. counters are integrated in rules themselves.
So in order to avoid ping pongs between cpus, we choose to allocate
one copy of rules/counters per cpu.
But with some changes, we could let the rules read-only and shared by
all cpus, and shadow counters only on percpu variables, thus reducing
memory costs.
--
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prev parent reply other threads:[~2009-04-05 12:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20090329234702.4988017f@desktop.r000n.info>
[not found] ` <8763hja8cy.fsf@newton.gmurray.org.uk>
2009-04-05 8:22 ` Regression caused by commit "netfilter: iptables: lock free counters" David Miller
2009-04-05 10:01 ` Eric Dumazet
[not found] ` <87ws9z8l4c.fsf@newton.gmurray.org.uk>
2009-04-05 10:30 ` Eric Dumazet
2009-04-05 12:29 ` [PATCH] netfilter: ip6tables fix Eric Dumazet
2009-04-05 12:40 ` Eric Dumazet
2009-04-06 15:08 ` Patrick McHardy
2009-04-05 11:36 ` Regression caused by commit "netfilter: iptables: lock free counters" Jan Engelhardt
2009-04-05 12:34 ` Eric Dumazet [this message]
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