From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.11] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1DYQLS-0003ZI-MJ for user-mode-linux-devel@lists.sourceforge.net; Wed, 18 May 2005 08:20:26 -0700 Received: from dgate1.fujitsu-siemens.com ([217.115.66.35]) by sc8-sf-mx1.sourceforge.net with esmtp (Exim 4.41) id 1DYQLQ-00063N-VE for user-mode-linux-devel@lists.sourceforge.net; Wed, 18 May 2005 08:20:26 -0700 Message-ID: <428B5D30.6080706@fujitsu-siemens.com> From: Bodo Stroesser MIME-Version: 1.0 Subject: Re: [uml-devel] Explaination of system call function flow in TT mode References: <003e01c503b3$f3e46cb0$ac655e0a@sha.st.com> <200505162324.37749.blaisorblade@yahoo.it> <3524bf1f0505161709476c4940@mail.gmail.com> <200505170217.23138.blaisorblade@yahoo.it> <3524bf1f050517105676c6c051@mail.gmail.com> <20050517220053.GA10144@ccure.user-mode-linux.org> <428B0F2B.3060503@fujitsu-siemens.com> <20050518133331.GB3925@ccure.user-mode-linux.org> In-Reply-To: <20050518133331.GB3925@ccure.user-mode-linux.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Wed, 18 May 2005 17:20:16 +0200 To: Jeff Dike Cc: Young Koh , Blaisorblade , user-mode-linux-devel@lists.sourceforge.net Jeff Dike wrote: > On Wed, May 18, 2005 at 11:47:23AM +0200, Bodo Stroesser wrote: > >>I also thought about not saving FP-regs on each kernel entry. But if you do >>this optimization, you need to save / restore FP-regs on switch_to. Also you >>need to get the FP-regs when setting up a signal-handler stackframe. And >>they >>have to be restored on sys_(rt_)sigreturn from the values found in the >>stackframe. > > > True, but these are much less frequent than kernel entries/exits. Yes, so it makes sense to optimize this for i386 and x86_64. On s390, I'm not sure, what to do. Using s390's PTRACE_PEEK/POKEUSR_AREA UML can read or write all regs including FP in a single ptrace call. So, the change would speed up that call a bit, but would that be enough to pay the cost of additional ptrace calls in switch_to or signal handling? What do you think? Bodo > > >>I hope, I didn't miss some other places that would need adaption. > > > Offhand, this sounds right. > > Jeff ------------------------------------------------------- This SF.Net email is sponsored by Oracle Space Sweepstakes Want to be the first software developer in space? Enter now for the Oracle Space Sweepstakes! http://ads.osdn.com/?ad_id=7412&alloc_id=16344&op=click _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel