From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753502Ab1HXVKn (ORCPT ); Wed, 24 Aug 2011 17:10:43 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57829 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752116Ab1HXVKm (ORCPT ); Wed, 24 Aug 2011 17:10:42 -0400 Message-ID: <4E5568AC.2040605@zytor.com> Date: Wed, 24 Aug 2011 14:10:04 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0) Gecko/20110816 Thunderbird/6.0 MIME-Version: 1.0 To: Borislav Petkov CC: Andrew Lutomirski , Al Viro , Ingo Molnar , "user-mode-linux-devel@lists.sourceforge.net" , Richard Weinberger , "linux-kernel@vger.kernel.org" , "mingo@redhat.com" Subject: Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) References: <20110823010146.GY2203@ZenIV.linux.org.uk> <20110823011312.GZ2203@ZenIV.linux.org.uk> <20110823021717.GA2203@ZenIV.linux.org.uk> <20110823061531.GC2203@ZenIV.linux.org.uk> <20110823162251.GC13138@aftab> <4E53FC6E.1030807@zytor.com> <20110823205616.GA15295@aftab> <4E54163B.6080205@zytor.com> <20110823211047.GC15295@aftab> In-Reply-To: <20110823211047.GC15295@aftab> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/23/2011 02:10 PM, Borislav Petkov wrote: > On Tue, Aug 23, 2011 at 05:06:03PM -0400, H. Peter Anvin wrote: >> On 08/23/2011 01:56 PM, Borislav Petkov wrote: >>> >>> But no, I don't think the difference has disappeared - to the contrary, >>> AFAICT, the intention is for SYSCALL to be the fastest way to do >>> syscalls on x86 due to diminished number of segment checks etc. INT80 >>> is legacy, slower, etc. I believe Andy measured a similar situation on >>> Sandy Bridge with SYSCALL having latencies in the tens of nsecs range >>> and INT80 being much slower. Ingo also measured a similar situation >>> where the latency gap between the two on Intel is even bigger. >>> >> >> Sandy Bridge doesn't have SYSCALL32 at all. It has SYSENTER and SYSCALL64. > > Yeah, I was talking about SYSCALL in general. > By the way, Borislav; any way you could nudge your hardware people into a) supporting SYSENTER in compatibility mode, and b) giving us a way to turn SYSCALL *off* in compat mode? ... for future chips? -hpa From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1QwKiW-0007oX-4x for user-mode-linux-devel@lists.sourceforge.net; Wed, 24 Aug 2011 21:10:32 +0000 Received: from terminus.zytor.com ([198.137.202.10] helo=mail.zytor.com) by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1QwKiT-0000wP-T2 for user-mode-linux-devel@lists.sourceforge.net; Wed, 24 Aug 2011 21:10:32 +0000 Message-ID: <4E5568AC.2040605@zytor.com> Date: Wed, 24 Aug 2011 14:10:04 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 References: <20110823010146.GY2203@ZenIV.linux.org.uk> <20110823011312.GZ2203@ZenIV.linux.org.uk> <20110823021717.GA2203@ZenIV.linux.org.uk> <20110823061531.GC2203@ZenIV.linux.org.uk> <20110823162251.GC13138@aftab> <4E53FC6E.1030807@zytor.com> <20110823205616.GA15295@aftab> <4E54163B.6080205@zytor.com> <20110823211047.GC15295@aftab> In-Reply-To: <20110823211047.GC15295@aftab> List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net Subject: Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) To: Borislav Petkov Cc: Andrew Lutomirski , "user-mode-linux-devel@lists.sourceforge.net" , Richard Weinberger , "linux-kernel@vger.kernel.org" , "mingo@redhat.com" , Al Viro , Ingo Molnar On 08/23/2011 02:10 PM, Borislav Petkov wrote: > On Tue, Aug 23, 2011 at 05:06:03PM -0400, H. Peter Anvin wrote: >> On 08/23/2011 01:56 PM, Borislav Petkov wrote: >>> >>> But no, I don't think the difference has disappeared - to the contrary, >>> AFAICT, the intention is for SYSCALL to be the fastest way to do >>> syscalls on x86 due to diminished number of segment checks etc. INT80 >>> is legacy, slower, etc. I believe Andy measured a similar situation on >>> Sandy Bridge with SYSCALL having latencies in the tens of nsecs range >>> and INT80 being much slower. Ingo also measured a similar situation >>> where the latency gap between the two on Intel is even bigger. >>> >> >> Sandy Bridge doesn't have SYSCALL32 at all. It has SYSENTER and SYSCALL64. > > Yeah, I was talking about SYSCALL in general. > By the way, Borislav; any way you could nudge your hardware people into a) supporting SYSENTER in compatibility mode, and b) giving us a way to turn SYSCALL *off* in compat mode? ... for future chips? -hpa ------------------------------------------------------------------------------ EMC VNX: the world's simplest storage, starting under $10K The only unified storage solution that offers unified management Up to 160% more powerful than alternatives and 25% more efficient. Guaranteed. http://p.sf.net/sfu/emc-vnx-dev2dev _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel