From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH RFC]: napi_struct V4 Date: Sat, 28 Jul 2007 14:08:44 -0400 Message-ID: <46AB862C.9040507@garzik.org> References: <46A7FEFC.4040005@pobox.com> <20070725.185632.116383625.davem@davemloft.net> <46A8003F.1050208@garzik.org> <20070725.190245.68070169.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: shemminger@linux-foundation.org, netdev@vger.kernel.org, hadi@cyberus.ca, rusty@rustcorp.com.au To: David Miller Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:36708 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754092AbXG1SIt (ORCPT ); Sat, 28 Jul 2007 14:08:49 -0400 In-Reply-To: <20070725.190245.68070169.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org David Miller wrote: > From: Jeff Garzik > Date: Wed, 25 Jul 2007 22:00:31 -0400 > >> David Miller wrote: >>> From: Jeff Garzik >>> Date: Wed, 25 Jul 2007 21:55:08 -0400 >>> >>>> I don't see any logic to your request, only added overhead for no reason. >>> There may be some flawed logic in what Stephen stated, but >>> the change really is needed. >>> >>> It must be atomic to execute the: >>> >>> enable_interrupts(); >>> netif_rx_complete(); >>> >>> sequence wrt. the same code path in the interrupt handler. >> Sure. And how did the existing code fail to achieve that? > > The interrupt handler can run on another cpu in betwen those two > statements, running the NAPI test-and-do-something operations in > parallel with the netif_rx_complete() which causes problems as Rusty > and I discussed yesterday. That's a performance/parallelization regression from current NAPI :( Jeff