From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752520AbcGBQkc (ORCPT ); Sat, 2 Jul 2016 12:40:32 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:38676 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752261AbcGBQka (ORCPT ); Sat, 2 Jul 2016 12:40:30 -0400 Date: Sat, 2 Jul 2016 18:40:25 +0200 From: Peter Zijlstra To: Mark Rutland Cc: linux-kernel@vger.kernel.org, Alexander Shishkin , Arnaldo Carvalho de Melo , Ingo Molnar , Will Deacon Subject: Re: [PATCH] perf: fix pmu::filter_match for SW-led groups Message-ID: <20160702164025.GU30921@twins.programming.kicks-ass.net> References: <1465917041-15339-1-git-send-email-mark.rutland@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1465917041-15339-1-git-send-email-mark.rutland@arm.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 14, 2016 at 04:10:41PM +0100, Mark Rutland wrote: > However, pmu::filter_match is only called for the leader of each event > group. When the leader is a SW event, we do not filter the groups, and > may fail at pmu::add time, and when this happens we'll give up on > scheduling any event groups later in the list until they are rotated > ahead of the failing group. Ha! indeed. > I've tried to find a better way of handling this (without needing to walk the > siblings list), but so far I'm at a loss. At least it's "only" O(n) in the size > of the sibling list we were going to walk anyway. > > I suspect that at a more fundamental level, I need to stop sharing a > perf_hw_context between HW PMUs (i.e. replace task_struct::perf_event_ctxp with > something that can handle multiple HW PMUs). From previous attempts I'm not > sure if that's going to be possible. > > Any ideas appreciated! So I think I have half-cooked ideas. One of the problems I've been wanting to solve for a long time is that the per-cpu flexible list has priority over the per-task flexible list. I would like them to rotate together. One of the ways I was looking at getting that done is a virtual runtime scheduler (just like cfs). The tricky point is merging two virtual runtime trees. But I think that should be doable if we sort the trees on lag. In any case, the relevance to your question is that once we have a tree, we can play games with order; that is, if we first order on PMU-id and only second on lag, we get whole subtree clusters specific for a PMU. Lost of details missing in that picture, but I think something along those lines might get us what we want.