From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Horman Subject: Re: tun: Use netif_receive_skb instead of netif_rx Date: Wed, 19 May 2010 08:55:43 -0400 Message-ID: <20100519125543.GA26519@hmsreliant.think-freely.org> References: <20100519075721.GA23926@gondor.apana.org.au> <1274256582.2766.5.camel@edumazet-laptop> <1274257089.2766.7.camel@edumazet-laptop> <20100519120547.GB26584@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Eric Dumazet , Herbert Xu , "David S. Miller" , Thomas Graf , netdev@vger.kernel.org To: Neil Horman Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:54193 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752775Ab0ESM4D (ORCPT ); Wed, 19 May 2010 08:56:03 -0400 Content-Disposition: inline In-Reply-To: <20100519120547.GB26584@hmsreliant.think-freely.org> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, May 19, 2010 at 08:05:47AM -0400, Neil Horman wrote: > On Wed, May 19, 2010 at 10:18:09AM +0200, Eric Dumazet wrote: > > Le mercredi 19 mai 2010 =E0 10:09 +0200, Eric Dumazet a =E9crit : > >=20 > > > Another concern I have is about RPS. > > >=20 > > > netif_receive_skb() must be called from process_backlog() context= , or > > > there is no guarantee the IPI will be sent if this skb is enqueue= d for > > > another cpu. > >=20 > > Hmm, I just checked again, and this is wrong. > >=20 > > In case we enqueue skb on a remote cpu backlog, we also > > do __raise_softirq_irqoff(NET_RX_SOFTIRQ); so the IPI will be done > > later. > >=20 > But if this happens, then we loose the connection between the packet = being > received and the process doing the reception, so the network cgroup c= lassifier > breaks again. >=20 > Performance gains are still a big advantage here of course. > Neil >=20 Scratch what I said here, Herbert corrected me on this, and we're ok, a= s tun has no rps map. I'll test this patch out in just a bit Neil > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >=20