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authorPaul Mackerras <paulus@samba.org>2010-03-10 20:36:09 +1100
committerIngo Molnar <mingo@elte.hu>2010-03-11 13:36:53 +0100
commita12b51c478899fe0b7e874a559b05ba35f1128ee (patch)
tree25b9911c1932c13fd8b468aa18eb17982ba31b59 /tools
parent220b140b52ab6cc133f674a7ffec8fa792054f25 (diff)
perf tools: Fix sparse CPU numbering related bugs
At present, the perf subcommands that do system-wide monitoring (perf stat, perf record and perf top) don't work properly unless the online cpus are numbered 0, 1, ..., N-1. These tools ask for the number of online cpus with sysconf(_SC_NPROCESSORS_ONLN) and then try to create events for cpus 0, 1, ..., N-1. This creates problems for systems where the online cpus are numbered sparsely. For example, a POWER6 system in single-threaded mode (i.e. only running 1 hardware thread per core) will have only even-numbered cpus online. This fixes the problem by reading the /sys/devices/system/cpu/online file to find out which cpus are online. The code that does that is in tools/perf/util/cpumap.[ch], and consists of a read_cpu_map() function that sets up a cpumap[] array and returns the number of online cpus. If /sys/devices/system/cpu/online can't be read or can't be parsed successfully, it falls back to using sysconf to ask how many cpus are online and sets up an identity map in cpumap[]. The perf record, perf stat and perf top code then calls read_cpu_map() in the system-wide monitoring case (instead of sysconf) and uses cpumap[] to get the cpu numbers to pass to perf_event_open. Signed-off-by: Paul Mackerras <paulus@samba.org> Cc: Anton Blanchard <anton@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> LKML-Reference: <20100310093609.GA3959@brick.ozlabs.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/Makefile2
-rw-r--r--tools/perf/builtin-record.c7
-rw-r--r--tools/perf/builtin-stat.c10
-rw-r--r--tools/perf/builtin-top.c9
-rw-r--r--tools/perf/util/cpumap.c59
-rw-r--r--tools/perf/util/cpumap.h7
6 files changed, 81 insertions, 13 deletions
diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 2d537382c68..5840499e2d2 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -387,6 +387,7 @@ LIB_H += util/thread.h
LIB_H += util/trace-event.h
LIB_H += util/probe-finder.h
LIB_H += util/probe-event.h
+LIB_H += util/cpumap.h
LIB_OBJS += util/abspath.o
LIB_OBJS += util/alias.o
@@ -433,6 +434,7 @@ LIB_OBJS += util/sort.o
LIB_OBJS += util/hist.o
LIB_OBJS += util/probe-event.o
LIB_OBJS += util/util.o
+LIB_OBJS += util/cpumap.o
BUILTIN_OBJS += builtin-annotate.o
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f573bbb8357..b09d3b27ca1 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -22,6 +22,7 @@
#include "util/debug.h"
#include "util/session.h"
#include "util/symbol.h"
+#include "util/cpumap.h"
#include <unistd.h>
#include <sched.h>
@@ -421,9 +422,6 @@ static int __cmd_record(int argc, const char **argv)
char buf;
page_size = sysconf(_SC_PAGE_SIZE);
- nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
- assert(nr_cpus <= MAX_NR_CPUS);
- assert(nr_cpus >= 0);
atexit(sig_atexit);
signal(SIGCHLD, sig_handler);
@@ -547,8 +545,9 @@ static int __cmd_record(int argc, const char **argv)
if ((!system_wide && !inherit) || profile_cpu != -1) {
open_counters(profile_cpu, target_pid);
} else {
+ nr_cpus = read_cpu_map();
for (i = 0; i < nr_cpus; i++)
- open_counters(i, target_pid);
+ open_counters(cpumap[i], target_pid);
}
if (file_new) {
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index e8c85d5aec4..95db31cff6f 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -45,6 +45,7 @@
#include "util/event.h"
#include "util/debug.h"
#include "util/header.h"
+#include "util/cpumap.h"
#include <sys/prctl.h>
#include <math.h>
@@ -151,7 +152,7 @@ static void create_perf_stat_counter(int counter, int pid)
unsigned int cpu;
for (cpu = 0; cpu < nr_cpus; cpu++) {
- fd[cpu][counter] = sys_perf_event_open(attr, -1, cpu, -1, 0);
+ fd[cpu][counter] = sys_perf_event_open(attr, -1, cpumap[cpu], -1, 0);
if (fd[cpu][counter] < 0 && verbose)
fprintf(stderr, ERR_PERF_OPEN, counter,
fd[cpu][counter], strerror(errno));
@@ -519,9 +520,10 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
nr_counters = ARRAY_SIZE(default_attrs);
}
- nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
- assert(nr_cpus <= MAX_NR_CPUS);
- assert((int)nr_cpus >= 0);
+ if (system_wide)
+ nr_cpus = read_cpu_map();
+ else
+ nr_cpus = 1;
/*
* We dont want to block the signals - that would cause
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 31f2e597800..0b719e3dde0 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -28,6 +28,7 @@
#include <linux/rbtree.h>
#include "util/parse-options.h"
#include "util/parse-events.h"
+#include "util/cpumap.h"
#include "util/debug.h"
@@ -1123,7 +1124,7 @@ static void start_counter(int i, int counter)
cpu = profile_cpu;
if (target_pid == -1 && profile_cpu == -1)
- cpu = i;
+ cpu = cpumap[i];
attr = attrs + counter;
@@ -1347,12 +1348,10 @@ int cmd_top(int argc, const char **argv, const char *prefix __used)
attrs[counter].sample_period = default_interval;
}
- nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
- assert(nr_cpus <= MAX_NR_CPUS);
- assert(nr_cpus >= 0);
-
if (target_pid != -1 || profile_cpu != -1)
nr_cpus = 1;
+ else
+ nr_cpus = read_cpu_map();
get_term_dimensions(&winsize);
if (print_entries == 0) {
diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
new file mode 100644
index 00000000000..4e01490e51e
--- /dev/null
+++ b/tools/perf/util/cpumap.c
@@ -0,0 +1,59 @@
+#include "util.h"
+#include "../perf.h"
+#include "cpumap.h"
+#include <assert.h>
+#include <stdio.h>
+
+int cpumap[MAX_NR_CPUS];
+
+static int default_cpu_map(void)
+{
+ int nr_cpus, i;
+
+ nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+ assert(nr_cpus <= MAX_NR_CPUS);
+ assert((int)nr_cpus >= 0);
+
+ for (i = 0; i < nr_cpus; ++i)
+ cpumap[i] = i;
+
+ return nr_cpus;
+}
+
+int read_cpu_map(void)
+{
+ FILE *onlnf;
+ int nr_cpus = 0;
+ int n, cpu, prev;
+ char sep;
+
+ onlnf = fopen("/sys/devices/system/cpu/online", "r");
+ if (!onlnf)
+ return default_cpu_map();
+
+ sep = 0;
+ prev = -1;
+ for (;;) {
+ n = fscanf(onlnf, "%u%c", &cpu, &sep);
+ if (n <= 0)
+ break;
+ if (prev >= 0) {
+ assert(nr_cpus + cpu - prev - 1 < MAX_NR_CPUS);
+ while (++prev < cpu)
+ cpumap[nr_cpus++] = prev;
+ }
+ assert (nr_cpus < MAX_NR_CPUS);
+ cpumap[nr_cpus++] = cpu;
+ if (n == 2 && sep == '-')
+ prev = cpu;
+ else
+ prev = -1;
+ if (n == 1 || sep == '\n')
+ break;
+ }
+ fclose(onlnf);
+ if (nr_cpus > 0)
+ return nr_cpus;
+
+ return default_cpu_map();
+}
diff --git a/tools/perf/util/cpumap.h b/tools/perf/util/cpumap.h
new file mode 100644
index 00000000000..86c78bb3309
--- /dev/null
+++ b/tools/perf/util/cpumap.h
@@ -0,0 +1,7 @@
+#ifndef __PERF_CPUMAP_H
+#define __PERF_CPUMAP_H
+
+extern int read_cpu_map(void);
+extern int cpumap[];
+
+#endif /* __PERF_CPUMAP_H */