linux-kernel - [PATCH 14/19] perf tools: Make the breakpoint events sample period default to 1

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Date:	Wed, 25 Jul 2012 14:41:29 -0300
From:	Arnaldo Carvalho de Melo <acme@...radead.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Jovi Zhang <bookjovi@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 14/19] perf tools: Make the breakpoint events sample period default to 1

From: Jovi Zhang <bookjovi@...il.com>

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);
 }
-- 
1.7.1

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