Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755293AbZJAAr6 (ORCPT ); Wed, 30 Sep 2009 20:47:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755197AbZJAAr6 (ORCPT ); Wed, 30 Sep 2009 20:47:58 -0400 Received: from bay0-omc1-s28.bay0.hotmail.com ([65.54.246.100]:13311 "EHLO bay0-omc1-s28.bay0.hotmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755147AbZJAAr5 (ORCPT ); Wed, 30 Sep 2009 20:47:57 -0400 X-Greylist: delayed 359 seconds by postgrey-1.27 at vger.kernel.org; Wed, 30 Sep 2009 20:47:57 EDT Message-ID: X-Originating-IP: [173.64.154.25] From: Yuhong Bao To: , CC: Linus Torvalds , , , , Subject: RE: Linux 2.6.32-rc1 Date: Wed, 30 Sep 2009 17:42:02 -0700 Importance: Normal In-Reply-To: <20090930173102.2d54534c@infradead.org> References: <4AC060AE.1090401@gmail.com> <20090928191506.40b61793@mschwide.boeblingen.de.ibm.com> <4AC10365.7090802@gmail.com> <4AC2712C.4080901@gma X-OriginalArrivalTime: 01 Oct 2009 00:42:02.0916 (UTC) FILETIME=[FE336E40:01CA422F] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1862 Lines: 60 <20090930173102.2d54534c@infradead.org> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 ---------------------------------------- > Date: Wed=2C 30 Sep 2009 17:31:02 +0200 > From: arjan@infradead.org > To: eric.dumazet@gmail.com > CC: torvalds@linux-foundation.org=3B schwidefsky@de.ibm.com=3B tglx@linut= ronix.de=3B johnstul@us.ibm.com=3B linux-kernel@vger.kernel.org=3B a.p.zijl= stra@c > Subject: Re: Linux 2.6.32-rc1 > > On Wed=2C 30 Sep 2009 17:27:05 +0200 > Eric Dumazet wrote: >> >>> + pop %edi >> Why do you pop flags in edi=2C to later re-push them ? >> >>> + cli > > because here I disable interrupts But popping the flags to edi to later repush them should not be necessary u= nless you are switching esp. Getting rid of this will allow the push/pop edi at the beginning/end to be eliminated=2C reducing code size as well as increasing the speed. > (basically this is local_irq_save() ) >> >> >>> + xchg (%esi)=2C %ebx >>> + xchg 4(%esi)=2C %ecx >> How this sequence is guaranteed to be atomic with other cpus ? > > it is not. this is the 486 implementation which is !SMP > (just like the current cmpxchg64() fallback) BTW=2C NT4 had a SMP version of this emulation that used a simple spinlock: http://www.geoffchappell.com/viewer.htm?doc=3Dstudies/windows/km/cpu/cx8.ht= m Yuhong Bao =0A= _________________________________________________________________=0A= Insert movie times and more without leaving Hotmail=AE.=0A= http://windowslive.com/Tutorial/Hotmail/QuickAdd?ocid=3DTXT_TAGLM_WL_HM_Tut= orial_QuickAdd_062009= -- 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/