From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: TCPBacklogDrops during aggressive bursts of traffic Date: Wed, 23 May 2012 19:46:50 +0200 Message-ID: <1337795210.3361.3118.camel@edumazet-glaptop> References: <1337705135.3361.226.camel@edumazet-glaptop> <1337720076.3361.667.camel@edumazet-glaptop> <1337766246.3361.2447.camel@edumazet-glaptop> <20120523.133401.915684077769386834.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: kmansley@solarflare.com, bhutchings@solarflare.com, netdev@vger.kernel.org To: David Miller Return-path: Received: from mail-ey0-f174.google.com ([209.85.215.174]:54106 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760641Ab2EWRqz (ORCPT ); Wed, 23 May 2012 13:46:55 -0400 Received: by eaak11 with SMTP id k11so2161352eaa.19 for ; Wed, 23 May 2012 10:46:54 -0700 (PDT) In-Reply-To: <20120523.133401.915684077769386834.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2012-05-23 at 13:34 -0400, David Miller wrote: > But it is the only way we can have TCP processing scheduled and > accounted to user processes. That does have value when you have lots > of flows active. > > The scheduler's ability to give the process cpu time influences > TCP's behavier, and under load if the process can't get enough > cpu time then TCP will back off. We want that. But TCP already backs off if user process is not blocked on socket input. Modern applications uses select()/poll()/epoll() on many sockets in //. Only old ones stil block on recv().