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-rw-r--r--tools/perf/util/header.c51
1 files changed, 51 insertions, 0 deletions
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index d546ff724dbe..a27132e5a5ef 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -983,6 +983,57 @@ static int write_dir_format(struct feat_fd *ff,
return do_write(ff, &data->dir.version, sizeof(data->dir.version));
}
+/*
+ * Check whether a CPU is online
+ *
+ * Returns:
+ * 1 -> if CPU is online
+ * 0 -> if CPU is offline
+ * -1 -> error case
+ */
+int is_cpu_online(unsigned int cpu)
+{
+ char *str;
+ size_t strlen;
+ char buf[256];
+ int status = -1;
+ struct stat statbuf;
+
+ snprintf(buf, sizeof(buf),
+ "/sys/devices/system/cpu/cpu%d", cpu);
+ if (stat(buf, &statbuf) != 0)
+ return 0;
+
+ /*
+ * Check if /sys/devices/system/cpu/cpux/online file
+ * exists. Some cases cpu0 won't have online file since
+ * it is not expected to be turned off generally.
+ * In kernels without CONFIG_HOTPLUG_CPU, this
+ * file won't exist
+ */
+ snprintf(buf, sizeof(buf),
+ "/sys/devices/system/cpu/cpu%d/online", cpu);
+ if (stat(buf, &statbuf) != 0)
+ return 1;
+
+ /*
+ * Read online file using sysfs__read_str.
+ * If read or open fails, return -1.
+ * If read succeeds, return value from file
+ * which gets stored in "str"
+ */
+ snprintf(buf, sizeof(buf),
+ "devices/system/cpu/cpu%d/online", cpu);
+
+ if (sysfs__read_str(buf, &str, &strlen) < 0)
+ return status;
+
+ status = atoi(str);
+
+ free(str);
+ return status;
+}
+
#ifdef HAVE_LIBBPF_SUPPORT
static int write_bpf_prog_info(struct feat_fd *ff,
struct evlist *evlist __maybe_unused)