From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 1B67A8D0039 for ; Thu, 10 Mar 2011 12:23:29 -0500 (EST) References: <1299630721-4337-1-git-send-email-wilsons@start.ca> <20110310160032.GA20504@alboin.amr.corp.intel.com> <20110310163809.GA20675@alboin.amr.corp.intel.com> <20110310165414.GA6431@fibrous.localdomain> In-Reply-To: <20110310165414.GA6431@fibrous.localdomain> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----V09616JKR7L2B0NB8391YYHI8HKF8V" Subject: =?US-ASCII?Q?Re=3A_=5BPATCH_0/5=5D_make_*=5Fgate=5Fvma_accep?= =?US-ASCII?Q?t_mm=5Fstruct_instead_of=09task=5Fstruct_II?= From: "H. Peter Anvin" Date: Thu, 10 Mar 2011 09:22:48 -0800 Message-ID: <37e280c3-7f6b-4f1e-9589-68f4a67e4c0a@email.android.com> Sender: owner-linux-mm@kvack.org List-ID: To: Stephen Wilson , Andi Kleen Cc: x86@kernel.org, Thomas Gleixner , Ingo Molnar , Benjamin Herrenschmidt , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , linux390@de.ibm.com, Paul Mundt , Michel Lespinasse , Andrew Morton , Alexander Viro , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org ------V09616JKR7L2B0NB8391YYHI8HKF8V Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sorry... I confused them too. It's TS_COMPAT which is problematic. -- Sent from my mobile phone. Please pardon any lack of formatting. Stephen Wilson wrote: On Thu, Mar 10, 2011 at 08:38:09AM -0800, Andi Kleen wrote: > On Thu, Mar 10, 2011 at 08:00:32AM -0800, Andi Kleen wrote: > > On Tue, Mar 08, 2011 at 07:31:56PM -0500, Stephen Wilson wrote: > > > The only architecture this change impacts in any significant way is x86_64. > > > The principle change on that architecture is to mirror TIF_IA32 via > > > a new flag in mm_context_t. > > > > The problem is -- you're adding a likely cache miss on mm_struct for > > every 32bit compat syscall now, even if they don't need mm_struct > > currently (and a lot of them do not) Unless there's a very good > > justification to make up for this performance issue elsewhere > > (including numbers) this seems like a bad idea. > > Hmm I see you're only setting it on exec time actually on rereading > the patches. I thought you were changing TS_COMPAT which is in > the syscall path. > > Never mind. I have no problems with doing such a change on exec > time. OK. Great! Does this mean I have your ACK'e! d by or reviewed by? Thanks for taking a look! -- steve ------V09616JKR7L2B0NB8391YYHI8HKF8V Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit Sorry... I confused them too. It's TS_COMPAT which is problematic.
--
Sent from my mobile phone. Please pardon any lack of formatting.

Stephen Wilson <wilsons@start.ca> wrote:
On Thu, Mar 10, 2011 at 08:38:09AM -0800, Andi Kleen wrote: > On Thu, Mar 10, 2011 at 08:00:32AM -0800, Andi Kleen wrote: > > On Tue, Mar 08, 2011 at 07:31:56PM -0500, Stephen Wilson wrote: > > > The only architecture this change impacts in any significant way is x86_64. > > > The principle change on that architecture is to mirror TIF_IA32 via > > > a new flag in mm_context_t. > > > > The problem is -- you're adding a likely cache miss on mm_struct for > > every 32bit compat syscall now, even if they don't need mm_struct > > currently (and a lot of them do not) Unless there's a very good > > justification to make up for this performance issue elsewhere > > (including numbers) this seems like a bad idea. > > Hmm I see you're only setting it on exec time actually on rereading > the patches. I thought you were changing TS_COMPAT which is in > the syscall path. > > Never mind. I have no problems with doing such a change on exec > time. OK. Great! Does this mean I have your ACK'ed by or reviewed by? Thanks for taking a look! -- steve
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