linux-kernel - [tip:perf/core] perf tools: Make the breakpoint events sample period default to 1

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Message-ID: <tip-4a841d650ea435c69e60675537f158a620697290@git.kernel.org>
Date:	Wed, 25 Jul 2012 12:29:10 -0700
From:	tip-bot for Jovi Zhang <bookjovi@...il.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	acme@...hat.com, linux-kernel@...r.kernel.org, hpa@...or.com,
	mingo@...nel.org, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
	bookjovi@...il.com
Subject: [tip:perf/core] perf tools:
  Make the breakpoint events sample period default to 1

Commit-ID:  4a841d650ea435c69e60675537f158a620697290
Gitweb:     http://git.kernel.org/tip/4a841d650ea435c69e60675537f158a620697290
Author:     Jovi Zhang <bookjovi@...il.com>
AuthorDate: Sun, 15 Jul 2012 03:03:10 +0800
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Wed, 25 Jul 2012 11:37:46 -0300

perf tools: Make the breakpoint events sample period default to 1

There have one problem about hw_breakpoint perf event, as watched, the
events reported to userspace is not correctly, sometime one trigger
bp_event report several events, sometime bp_event cannot go through to
user.

The root cause is attr->freq is 1 passed to kernel defaultly in bp
events, this make kernel calculate event period not as expect, make
sample period to 1 will change attr->freq to 0, to fix this problem.

This patch is similar with commit f92128 about tracepoint events:
    perf: Make the trace events sample period default to 1

Signed-off-by: Jovi Zhang <bookjovi@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/r/CACV3sbLF8taiCq_VYW-sgRJyupeMzg58C7ZXfMe3xZUiH_Mx6w@mail.gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/parse-events.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index a729945..74a5af4 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -490,6 +490,7 @@ int parse_events_add_breakpoint(struct list_head **list, int *idx,
 		attr.bp_len = HW_BREAKPOINT_LEN_4;
 
 	attr.type = PERF_TYPE_BREAKPOINT;
+	attr.sample_period = 1;
 
 	return add_event(list, idx, &attr, NULL);
 }
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