From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH nf-next-2.6 2/2] conntrack: per_cpu untracking Date: Tue, 08 Jun 2010 16:52:13 +0200 Message-ID: <1276008733.2486.177.camel@edumazet-laptop> References: <1271941082.14501.189.camel@jdb-workstation> <1271948029.7895.5707.camel@edumazet-laptop> <20100422155123.GA2524@linux.vnet.ibm.com> <1271952128.7895.5851.camel@edumazet-laptop> <1272056237.4599.7.camel@edumazet-laptop> <1272139861.20714.525.camel@edumazet-laptop> <1272292568.13192.43.camel@jdb-workstation> <1275340896.2478.26.camel@edumazet-laptop> <1275368732.2478.88.camel@edumazet-laptop> <4C04DE73.6050605@trash.net> <1275388310.2738.2.camel@edumazet-laptop> <4C04E3E2.7020209@trash.net> <1275409203.2738.227.camel@edumazet-laptop> <4C08E62A.9020607@trash.net> <4C08F1A4.2050906@trash.net> <1275654964.2482.150.camel@edumazet-laptop> <1275668732.2482.201.camel@edumazet-laptop> <1275682522.2490.6.camel@edumazet-laptop> <4C0E53C4.7090308@trash.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Changli Gao , Netfilter Developers , netdev To: Patrick McHardy Return-path: In-Reply-To: <4C0E53C4.7090308@trash.net> Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Le mardi 08 juin 2010 =C3=A0 16:29 +0200, Patrick McHardy a =C3=A9crit = : > On 04.06.2010 22:15, Eric Dumazet wrote: > > NOTRACK makes all cpus share a cache line on nf_conntrack_untracked > > twice per packet, slowing down performance. > >=20 > > This patch converts it to a per_cpu variable. > >=20 > > We assume same cpu is used for a given packet, entering and exiting= the > > NOTRACK state. >=20 > That doesn't seem to be a valid assumption, the conntrack entry is > attached to the skb and processing in the output path might get > preempted and rescheduled to a different CPU. Thats unfortunate. Ok, only choice then is to not change refcount on the untracked ct, and keep a shared (read only after setup time) untrack structure. -- To unsubscribe from this list: send the line "unsubscribe netfilter-dev= el" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html