From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934602AbeCELb3 (ORCPT ); Mon, 5 Mar 2018 06:31:29 -0500 Received: from mga02.intel.com ([134.134.136.20]:53105 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933589AbeCELb0 (ORCPT ); Mon, 5 Mar 2018 06:31:26 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,426,1515484800"; d="scan'208";a="22125194" Subject: Re: [RFC] perf: a different approach to perf_rotate_context() To: Peter Zijlstra , Song Liu Cc: "linux-kernel@vger.kernel.org" , "jolsa@redhat.com" , Kernel Team References: <20180301195321.2608515-1-songliubraving@fb.com> <20180303152631.GF25201@hirez.programming.kicks-ass.net> <20180303174808.GJ25201@hirez.programming.kicks-ass.net> From: Alexey Budankov Organization: Intel Corp. Message-ID: <9ad03edb-7dc2-6fc8-7978-6257a7746aec@linux.intel.com> Date: Mon, 5 Mar 2018 14:31:23 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180303174808.GJ25201@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03.03.2018 20:48, Peter Zijlstra wrote: > On Sat, Mar 03, 2018 at 04:43:16PM +0000, Song Liu wrote: >>> In any case, there's a ton of conflict against the patches here: >>> >>> https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/log/?h=perf/testing >>> >>> And with those the idea was to move to a virtual time based scheduler >>> (basically schedule those flexible events that have the biggest lag -- >>> that also solves 1). >> >> Thanks for these information. I will study this approach. Maybe that is >> our path to PMU sharing. > > So I'm really not convinced on that whole PMU sharing. > >> What's is the status of this work? Would it >> land in 4.17? > > These patches might make 4.17, they got held up because of the whole > meltdown/spectre crap and I need to get back to them. > That work is long desired and would bring performance boost, specifically on server systems in per-process profiling mode, accompanied by good speedup on context switches. Undoubtedly meltdown/spectre related activity substituted it at some point but that improvements would still bring significant value and is still awaited. BR, Alexey