Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754735Ab0KDFnC (ORCPT ); Thu, 4 Nov 2010 01:43:02 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:39266 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754559Ab0KDFm7 (ORCPT ); Thu, 4 Nov 2010 01:42:59 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=J2Nc41Zi04Lzc3wnfcjvxPySuxiqw5fHdD1bOTEFyZVwbmRNmpcCiOg6xYtDABE7J2 PRvr4V5IuVLQALopEYajyfzPXxTCBA4GIzY4VZi0J/gHA3xXKNWbq85hTn3ct740HxWB PSVhLMrYvb9+tAeEk7DZW4Yr1PrWqjnJksmv8= Subject: Re: [RFC 4/4]x86: avoid tlbstate lock if no enough cpus From: Eric Dumazet To: Shaohua Li Cc: lkml , Ingo Molnar , Andi Kleen , "hpa@zytor.com" In-Reply-To: <1288848079.23014.131.camel@sli10-conroe> References: <1288766668.23014.117.camel@sli10-conroe> <1288767580.2467.636.camel@edumazet-laptop> <1288767995.23014.120.camel@sli10-conroe> <1288768330.2467.660.camel@edumazet-laptop> <1288768795.23014.123.camel@sli10-conroe> <1288769123.2467.681.camel@edumazet-laptop> <1288769486.2467.690.camel@edumazet-laptop> <1288773716.23014.124.camel@sli10-conroe> <1288775282.2511.9.camel@edumazet-laptop> <1288848079.23014.131.camel@sli10-conroe> Content-Type: text/plain; charset="UTF-8" Date: Thu, 04 Nov 2010 06:42:46 +0100 Message-ID: <1288849366.2718.42.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1333 Lines: 43 Le jeudi 04 novembre 2010 à 13:21 +0800, Shaohua Li a écrit : > On Wed, 2010-11-03 at 17:08 +0800, Eric Dumazet wrote: > > Le mercredi 03 novembre 2010 à 16:41 +0800, Shaohua Li a écrit : > > > > > yes, this is ok. we might need avoid some cpu hotplug race too. I'll > > > post a new patch later. > > > > > > > > > > Hmm, maybe only set the variable "must take the lock", never unset it. > I followed your suggestions to use nr_cpu_ids, it should be good enough. > Yes, unfortunately not on HP machines, because of their tendency to have holes in CPU numberings :) This can probably can improved later. Thanks > Thanks, > Shaohua > > > This one isn't related to previous patch. If online cpus are below > NUM_INVALIDATE_TLB_VECTORS, we don't need the lock. The comments > in the code declares we don't need the check, but a hot lock still > needs an atomic operation and expensive, so add the check here. > > Uses nr_cpu_ids here as suggested by Eric Dumazet. > > Signed-off-by: Shaohua Li > --- Acked-by: Eric Dumazet -- 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/