Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966876Ab3E2UUr (ORCPT ); Wed, 29 May 2013 16:20:47 -0400 Received: from webmail.solarflare.com ([12.187.104.25]:36693 "EHLO webmail.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966780Ab3E2UUl (ORCPT ); Wed, 29 May 2013 16:20:41 -0400 Message-ID: <1369858835.1971.26.camel@bwh-desktop.uk.level5networks.com> Subject: Re: [PATCH v6 net-next 2/5] net: implement support for low latency socket polling From: Ben Hutchings To: Or Gerlitz CC: Eliezer Tamir , Eric Dumazet , David Miller , , , Jesse Brandeburg , Don Skidmore , , Willem de Bruijn , Andi Kleen , HPA , Eilon Greenstien , Alex Rosenbaum , Eliezer Tamir Date: Wed, 29 May 2013 21:20:35 +0100 In-Reply-To: References: <20130529063916.27486.3841.stgit@ladj378.jer.intel.com> <20130529063935.27486.18610.stgit@ladj378.jer.intel.com> Organization: Solarflare Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4 (3.6.4-3.fc18) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.17.20.137] X-TM-AS-Product-Ver: SMEX-10.0.0.1412-7.000.1014-19900.004 X-TM-AS-Result: No--22.817600-0.000000-31 X-TM-AS-User-Approved-Sender: Yes X-TM-AS-User-Blocked-Sender: No Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1494 Lines: 31 On Wed, 2013-05-29 at 17:14 +0300, Or Gerlitz wrote: > On Wed, May 29, 2013 at 9:39 AM, Eliezer Tamir > wrote: > > Adds a new ndo_ll_poll method and the code that supports and uses it. > > This method can be used by low latency applications to busy poll Ethernet > > device queues directly from the socket code. The value of sysctl_net_ll_poll > > controls how many microseconds to poll. Set to zero to disable. > > Unlike with TCP sockets, UDP sockets may receive packets from multiple > sources and hence the receiving context may be steered to be executed > on different cores through RSS or other Flow-Steering HW mechanisms > which could mean different napi contexts for the same socket, is that > a problem here? what's the severity? Maybe ARFS could be extended so the driver can tell whether a UDP socket it's steering for is connected or not. Then for disconnected sockets the driver can use a filter that only matches destination address. (Though that's probably undesirable if the socket has SO_REUSEPORT set.) Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/