From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 18 Sep 2002 10:43:13 +0200 (CEST) Received: from mx2.mips.com ([206.31.31.227]:25307 "EHLO mx2.mips.com") by linux-mips.org with ESMTP id ; Wed, 18 Sep 2002 10:43:12 +0200 Received: from newman.mips.com (ns-dmz [206.31.31.225]) by mx2.mips.com (8.12.5/8.12.5) with ESMTP id g8I8h5UD009676; Wed, 18 Sep 2002 01:43:05 -0700 (PDT) Received: from grendel (grendel [192.168.236.16]) by newman.mips.com (8.9.3/8.9.0) with SMTP id BAA25145; Wed, 18 Sep 2002 01:43:12 -0700 (PDT) Message-ID: <004101c25eef$ba035350$10eca8c0@grendel> From: "Kevin D. Kissell" To: "Jun Sun" Cc: References: <20020917160425.O17321@mvista.com> <01b801c25ea7$ce074ed0$10eca8c0@grendel> <20020917171434.Q17321@mvista.com> Subject: Re: [jsun@mvista.com: Re: [RFC] FPU context switch] Date: Wed, 18 Sep 2002 10:45:08 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4807.1700 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4910.0300 Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 231 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: kevink@mips.com Precedence: bulk X-list: linux-mips From: "Jun Sun" > On Wed, Sep 18, 2002 at 02:10:17AM +0200, Kevin D. Kissell wrote: > > Are you able to test this stuff on a proper SMP > > system, by the way? The efficiency of the code > > that manipulates interprocessor control variables > > can reasonably be expected to drop off a bit > > in a system with MP cache invalidations blasting > > left and right. > > Yes. I understand this effect. Solution 1), 2) > and 3) don't really suffer from this problem because > variables tested & manipulated are local - unless the > process migrates which is a different problem. It's not a "different problem", it's the heart of the problem. If we weren't worried about SMP behavior, we wouldn't be revisiting this stuff. While (1) can obviously be done without any global knowledge, as could something (2)-like based on CPU-local state such as Status.CU1, (2), (3) and (4), as you describe them, all depend to some degree on shared multiprocessor variables to determine whether to save or restore FP state. Regards, Kevin K. From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <004101c25eef$ba035350$10eca8c0@grendel> From: "Kevin D. Kissell" References: <20020917160425.O17321@mvista.com> <01b801c25ea7$ce074ed0$10eca8c0@grendel> <20020917171434.Q17321@mvista.com> Subject: Re: [jsun@mvista.com: Re: [RFC] FPU context switch] Date: Wed, 18 Sep 2002 10:45:08 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-Path: Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org To: Jun Sun Cc: linux-mips@linux-mips.org Message-ID: <20020918084508.U6Z1YAmRdG6FHhGZnxNUsDah-_x3u6jFQ1Y72JKOwF8@z> From: "Jun Sun" > On Wed, Sep 18, 2002 at 02:10:17AM +0200, Kevin D. Kissell wrote: > > Are you able to test this stuff on a proper SMP > > system, by the way? The efficiency of the code > > that manipulates interprocessor control variables > > can reasonably be expected to drop off a bit > > in a system with MP cache invalidations blasting > > left and right. > > Yes. I understand this effect. Solution 1), 2) > and 3) don't really suffer from this problem because > variables tested & manipulated are local - unless the > process migrates which is a different problem. It's not a "different problem", it's the heart of the problem. If we weren't worried about SMP behavior, we wouldn't be revisiting this stuff. While (1) can obviously be done without any global knowledge, as could something (2)-like based on CPU-local state such as Status.CU1, (2), (3) and (4), as you describe them, all depend to some degree on shared multiprocessor variables to determine whether to save or restore FP state. Regards, Kevin K.