Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932274AbWCHVWz (ORCPT ); Wed, 8 Mar 2006 16:22:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932278AbWCHVWz (ORCPT ); Wed, 8 Mar 2006 16:22:55 -0500 Received: from kanga.kvack.org ([66.96.29.28]:46501 "EHLO kanga.kvack.org") by vger.kernel.org with ESMTP id S932274AbWCHVWy (ORCPT ); Wed, 8 Mar 2006 16:22:54 -0500 Date: Wed, 8 Mar 2006 16:17:33 -0500 From: Benjamin LaHaise To: Ravikiran G Thirumalai Cc: Andrew Morton , linux-kernel@vger.kernel.org, davem@davemloft.net, netdev@vger.kernel.org, shai@scalex86.org Subject: Re: [patch 1/4] net: percpufy frequently used vars -- add percpu_counter_mod_bh Message-ID: <20060308211733.GA5410@kvack.org> References: <20060308015808.GA9062@localhost.localdomain> <20060308015934.GB9062@localhost.localdomain> <20060307181301.4dd6aa96.akpm@osdl.org> <20060308202656.GA4493@localhost.localdomain> <20060308203642.GZ5410@kvack.org> <20060308210726.GD4493@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060308210726.GD4493@localhost.localdomain> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1038 Lines: 24 On Wed, Mar 08, 2006 at 01:07:26PM -0800, Ravikiran G Thirumalai wrote: > But on non x86, local_bh_disable() is gonna be cheaper than a cli/atomic op no? > (Even if they were switched over to do local_irq_save() and > local_irq_restore() from atomic_t's that is). It's still more expensive than local_t. > And if we use local_t, we will add the overhead for the non bh > percpu_counter_mod for non x86 arches. Last time I checked, all the major architectures had efficient local_t implementations. Most of the RISC CPUs are able to do a load / store conditional implementation that is the same cost (since memory barriers tend to be explicite on powerpc). So why not use it? -ben -- "Time is of no importance, Mr. President, only life is important." Don't Email: . - 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/