linux-kernel - [PATCH] perf sched timehist: Add support for filtering on CPU

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Date:   Wed,  4 Dec 2019 10:39:25 -0700
From:   David Ahern <dsahern@...nel.org>
To:     acme@...nel.org
Cc:     namhyung@...nel.org, jolsa@...nel.org,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        David Ahern <dsahern@...il.com>
Subject: [PATCH] perf sched timehist: Add support for filtering on CPU

From: David Ahern <dsahern@...il.com>

Allow user to limit output to one or more CPUs. Really helpful on systems
with a large number of cpus.

Signed-off-by: David Ahern <dsahern@...il.com>
---
 tools/perf/Documentation/perf-sched.txt |  4 ++++
 tools/perf/builtin-sched.c              | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/tools/perf/Documentation/perf-sched.txt b/tools/perf/Documentation/perf-sched.txt
index 63f938b887dd..5fbe42bd599b 100644
--- a/tools/perf/Documentation/perf-sched.txt
+++ b/tools/perf/Documentation/perf-sched.txt
@@ -110,6 +110,10 @@ OPTIONS for 'perf sched timehist'
 --max-stack::
 	Maximum number of functions to display in backtrace, default 5.
 
+-C=::
+--cpu=::
+	Only show events for the given CPU(s) (comma separated list).
+
 -p=::
 --pid=::
 	Only show events for given process ID (comma separated list).
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 8a12d71364c3..82fcc2c15fe4 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -51,6 +51,9 @@
 #define SYM_LEN			129
 #define MAX_PID			1024000
 
+static const char *cpu_list;
+static DECLARE_BITMAP(cpu_bitmap, MAX_NR_CPUS);
+
 struct sched_atom;
 
 struct task_desc {
@@ -2008,6 +2011,9 @@ static void timehist_print_sample(struct perf_sched *sched,
 	char nstr[30];
 	u64 wait_time;
 
+	if (cpu_list && !test_bit(sample->cpu, cpu_bitmap))
+		return;
+
 	timestamp__scnprintf_usec(t, tstr, sizeof(tstr));
 	printf("%15s [%04d] ", tstr, sample->cpu);
 
@@ -2994,6 +3000,12 @@ static int perf_sched__timehist(struct perf_sched *sched)
 	if (IS_ERR(session))
 		return PTR_ERR(session);
 
+	if (cpu_list) {
+		err = perf_session__cpu_bitmap(session, cpu_list, cpu_bitmap);
+		if (err < 0)
+			goto out;
+	}
+
 	evlist = session->evlist;
 
 	symbol__init(&session->header.env);
@@ -3429,6 +3441,7 @@ int cmd_sched(int argc, const char **argv)
 		   "analyze events only for given process id(s)"),
 	OPT_STRING('t', "tid", &symbol_conf.tid_list_str, "tid[,tid...]",
 		   "analyze events only for given thread id(s)"),
+	OPT_STRING('C', "cpu", &cpu_list, "cpu", "list of cpus to profile"),
 	OPT_PARENT(sched_options)
 	};
 
-- 
2.20.1