linux-kernel - Re: [2.6.39-rc2] perf top fails to mmap

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Message-Id: <1303570271.3363.4.camel@localhost>
Date:	Sat, 23 Apr 2011 22:51:11 +0800
From:	Lin Ming <ming.m.lin@...el.com>
To:	David Ahern <dsahern@...il.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Tim Blechmann <tim@...ngt.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [2.6.39-rc2] perf top fails to mmap - bisected to 70db7533

On Sat, 2011-04-23 at 22:36 +0800, Lin Ming wrote:
> On Sat, Apr 23, 2011 at 12:37 AM, David Ahern <dsahern@...il.com> wrote:
> > I know you've been busy with other stuff the past few weeks, but have
> > you had a chance to look into this? Basically, perf in 2.6.39 is broken
> > when trying to profile a process (-p argument to record or top).
> 
> Let me take a look at this.

Below patch fixes the same problem on my box.
Could you have a try it? 

>>From 89f1ab02cd8da55f8829b2f2d7e700fdae77b3af Mon Sep 17 00:00:00 2001
From: Lin Ming <ming.m.lin@...el.com>
Date: Sat, 23 Apr 2011 14:54:33 +0000
Subject: [PATCH] perf: Allow set output event for task in the same thread group

Signed-off-by: Lin Ming <ming.m.lin@...el.com>
---
 kernel/perf_event.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 8e81a98..17dbc49 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -6379,9 +6379,10 @@ perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
 		goto out;
 
 	/*
-	 * If its not a per-cpu buffer, it must be the same task.
+	 * If its not a per-cpu buffer, it must be the same task or in the same thread group.
 	 */
-	if (output_event->cpu == -1 && output_event->ctx != event->ctx)
+	if (output_event->cpu == -1 &&
+			!same_thread_group(output_event->ctx->task, event->ctx->task))
 		goto out;
 
 set:


> 
> Lin Ming
> 
> >
> > David


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