Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751508AbZIYFwO (ORCPT ); Fri, 25 Sep 2009 01:52:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750848AbZIYFwM (ORCPT ); Fri, 25 Sep 2009 01:52:12 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:58829 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750769AbZIYFwL (ORCPT ); Fri, 25 Sep 2009 01:52:11 -0400 Message-ID: <4ABC5A55.7000208@cn.fujitsu.com> Date: Fri, 25 Sep 2009 13:51:17 +0800 From: Xiao Guangrong User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Ingo Molnar CC: Peter Zijlstra , Paul Mackerras , LKML Subject: [PATCH 1/2 v2] perf_counter: fix for __perf_event_sched_*() References: <4AB88F06.10900@cn.fujitsu.com> <19128.39768.149110.673711@cargo.ozlabs.ibm.com> <4AB98BB0.6020202@cn.fujitsu.com> <19129.38627.94363.857137@cargo.ozlabs.ibm.com> <4AB9D7FA.5040707@cn.fujitsu.com> <1253695230.7695.122.camel@twins> In-Reply-To: <1253695230.7695.122.camel@twins> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3427 Lines: 105 Paul Mackerras says: "Actually, looking at this more closely, it has to be a group leader anyway since it's at the top level of ctx->group_list. In fact I see four places where we do: list_for_each_entry(event, &ctx->group_list, group_entry) { if (event == event->group_leader) ... or the equivalent, three of which appear to have been introduced by afedadf2 ("perf_counter: Optimize sched in/out of counters") back in May by Peter Z. As far as I can see the if () is superfluous in each case (a singleton event will be a group of 1 and will have its group_leader pointing to itself)." [Can be found at http://marc.info/?l=linux-kernel&m=125361238901442&w=2] And Peter Zijlstra point out this is an bugfix: "The intent was to call event_sched_{in,out}() for single counter groups because that's cheaper than group_sched_{in,out}(), however.. - as you noticed, I got the condition wrong, it should have read: list_empty(&event->sibling_list) - it failed to call group_can_go_on() which deals with ->exclusive. - it also doesn't call hw_perf_group_sched_in() which might break power." [Can be found at http://marc.info/?l=linux-kernel&m=125369523318583&w=2] Changelog v1->v2: - fix the title name as Peter Zijlstra's suggestion - remove the comments and WARN_ON_ONCE() as Peter Zijlstra's suggestion Signed-off-by: Xiao Guangrong --- kernel/perf_event.c | 30 ++++++++---------------------- 1 files changed, 8 insertions(+), 22 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 76ac4db..2a15cd6 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -1030,14 +1030,10 @@ void __perf_event_sched_out(struct perf_event_context *ctx, update_context_time(ctx); perf_disable(); - if (ctx->nr_active) { - list_for_each_entry(event, &ctx->group_list, group_entry) { - if (event != event->group_leader) - event_sched_out(event, cpuctx, ctx); - else - group_sched_out(event, cpuctx, ctx); - } - } + if (ctx->nr_active) + list_for_each_entry(event, &ctx->group_list, group_entry) + group_sched_out(event, cpuctx, ctx); + perf_enable(); out: spin_unlock(&ctx->lock); @@ -1258,12 +1254,8 @@ __perf_event_sched_in(struct perf_event_context *ctx, if (event->cpu != -1 && event->cpu != cpu) continue; - if (event != event->group_leader) - event_sched_in(event, cpuctx, ctx, cpu); - else { - if (group_can_go_on(event, cpuctx, 1)) - group_sched_in(event, cpuctx, ctx, cpu); - } + if (group_can_go_on(event, cpuctx, 1)) + group_sched_in(event, cpuctx, ctx, cpu); /* * If this pinned group hasn't been scheduled, @@ -1291,15 +1283,9 @@ __perf_event_sched_in(struct perf_event_context *ctx, if (event->cpu != -1 && event->cpu != cpu) continue; - if (event != event->group_leader) { - if (event_sched_in(event, cpuctx, ctx, cpu)) + if (group_can_go_on(event, cpuctx, can_add_hw)) + if (group_sched_in(event, cpuctx, ctx, cpu)) can_add_hw = 0; - } else { - if (group_can_go_on(event, cpuctx, can_add_hw)) { - if (group_sched_in(event, cpuctx, ctx, cpu)) - can_add_hw = 0; - } - } } perf_enable(); out: -- 1.6.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/