From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH 3/3] chelsio: more receive cleanup Date: Fri, 15 Dec 2006 17:28:00 -0800 Message-ID: <20061215172800.52713c89@freekitty> References: <20061215190716.956791000@osdl.org> <20061215190813.803776000@osdl.org> <20061215201019.GA11385@electric-eye.fr.zoreil.com> <20061215145533.4cda3f23@freekitty> <20061216002604.GA11284@electric-eye.fr.zoreil.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Jeff Garzik , netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.25]:34005 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030528AbWLPB2L (ORCPT ); Fri, 15 Dec 2006 20:28:11 -0500 To: Francois Romieu In-Reply-To: <20061216002604.GA11284@electric-eye.fr.zoreil.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Sat, 16 Dec 2006 01:26:04 +0100 Francois Romieu wrote: > Stephen Hemminger : > > Francois Romieu wrote: > [...] > > Why, you can't predict copybreak on off > > Plain gut feeling. I'd rather spend extra cycles on small packets (whose > allocation is already optimized) and keep the normal packets less expensive > on a 10Gb/s network card. > Likely/unlikely is an optimization that doesn't make a big difference and I would rather the compiler choose unless it is something obvious like an error path or external interrupt (like PHY). There was some discussion on LKML, which I mostly forgot, that hinted that on some architectures using likely/unlikely incorrectly could have a major hit. -- Stephen Hemminger