From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Metcalf Subject: Re: [PATCH v9 00/13] support "task_isolation" mode for nohz_full Date: Tue, 12 Jan 2016 12:49:46 -0500 Message-ID: <56953CBA.9090208@ezchip.com> References: <1451936091-29247-1-git-send-email-cmetcalf@ezchip.com> <56941B86.9090009@ezchip.com> <20160112100708.GA15737@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160112100708.GA15737-5wv7dgnIgG8@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Will Deacon Cc: Gilad Ben Yossef , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Andrew Morton , Rik van Riel , Tejun Heo , Frederic Weisbecker , Thomas Gleixner , "Paul E. McKenney" , Christoph Lameter , Viresh Kumar , Catalin Marinas , Andy Lutomirski , Daniel Lezcano , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mark Rutland List-Id: linux-api@vger.kernel.org (Adding Mark to cc's) On 01/12/2016 05:07 AM, Will Deacon wrote: > On Mon, Jan 11, 2016 at 04:15:50PM -0500, Chris Metcalf wrote: >> Ping! There has been no substantive feedback to this version of >> the patch in the week since I posted it, which optimistically suggests >> to me that people may be satisfied with it. If that's true, Frederic, >> I assume this would be pulled into your tree? >> >> I have slightly updated the v9 patch series since this posting: >> >> [...] >> >> - Incorporated Mark Rutland's changes to convert arm64 >> assembly to C code instead of using my own version. > Please avoid queuing these patches -- the first is already in the arm64 > queue for 4.5 and the second was found to introduce a substantial > performance regression on the syscall entry/exit path. I think Mark had > an updated version to address that, so it would be easier not to have > an old version sitting in some other queue! I am not formally queueing them anywhere (like linux-next), though now that you mention it, that's a pretty good idea - I'll talk to Steven about that, assuming this merge window closes without the task isolation stuff going in. In the arch/tile code, we load the thread_info_flags and test them against a bitmask before we call into C code, to avoid the various overheads involved in the C path. Perhaps that same strategy is all that's needed for the arm64 code? Hopefully you can get that code merged up during the 4.5 window so I can use it as the new baseline for the task isolation stuff. Thanks! -- Chris Metcalf, EZChip Semiconductor http://www.ezchip.com