[PATCH 1/4 v2] perf: Allow ability to map cpus to nodes easily

[Don Zickus]

This patch figures out the max number of cpus and nodes that are on the
system and creates a map of cpu to node.  This allows us to provide a cpu
and quickly get the node associated with it.

It was mostly copied from builtin-kmem.c and tweaked slightly to use less memory
(use possible cpus instead of max).  It also calculates the max number of nodes.

V6: use original kernel_max reference
V5: use sysfs_mountpoint and filename__read_str
V4: fix typos, rename get_max_num
V3: simplify function names

Signed-off-by: Don Zickus <dzickus@xxxxxxxxxx>
---
 tools/perf/util/cpumap.c | 149 +++++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/cpumap.h |  35 +++++++++++
 2 files changed, 184 insertions(+)

diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index 7fe4994..1b75434 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -317,3 +317,152 @@ int cpu_map__build_core_map(struct cpu_map *cpus, struct cpu_map **corep)
 {
 	return cpu_map__build_map(cpus, corep, cpu_map__get_core);
 }
+
+/* setup simple routines to easily access node numbers given a cpu number */
+static int get_max_num(char *path, int *max)
+{
+	size_t num;
+	char *buf;
+	int err = 0;
+
+	if (filename__read_str(path, &buf, &num))
+		return -1;
+
+	buf[num] = '\0';
+
+	/* start on the right, to find highest node num */
+	while (--num) {
+		if ((buf[num] == ',') || (buf[num] == '-')) {
+			num++;
+			break;
+		}
+	}
+	if (sscanf(&buf[num], "%d", max) < 1) {
+		err = -1;
+		goto out;
+	}
+
+	/* convert from 0-based to 1-based */
+	(*max)++;
+
+out:
+	free(buf);
+	return err;
+}
+
+/* Determine highest possible cpu in the system for sparse allocation */
+static void set_max_cpu_num(void)
+{
+	const char *mnt;
+	char path[PATH_MAX];
+	int ret = -1;
+
+	/* set up default */
+	max_cpu_num = 4096;
+
+	mnt = sysfs__mountpoint();
+	if (!mnt)
+		goto out;
+
+	/* get the highest possible cpu number for a sparse allocation */
+	snprintf(path, PATH_MAX, "%s/devices/system/cpu/kernel_max", mnt);
+
+	ret = get_max_num(path, &max_cpu_num);
+
+out:
+	if (ret)
+		pr_err("Failed to read max cpus, using default of %d\n",
+			max_cpu_num);
+	return;
+}
+
+/* Determine highest possible node in the system for sparse allocation */
+static void set_max_node_num(void)
+{
+	const char *mnt;
+	char path[PATH_MAX];
+	int ret = -1;
+
+	/* set up default */
+	max_node_num = 8;
+
+	mnt = sysfs__mountpoint();
+	if (!mnt)
+		goto out;
+
+	/* get the highest possible cpu number for a sparse allocation */
+	snprintf(path, PATH_MAX, "%s/devices/system/node/possible", mnt);
+
+	ret = get_max_num(path, &max_node_num);
+
+out:
+	if (ret)
+		pr_err("Failed to read max nodes, using default of %d\n",
+			max_node_num);
+	return;
+}
+
+static int init_cpunode_map(void)
+{
+	int i;
+
+	set_max_cpu_num();
+	set_max_node_num();
+
+	cpunode_map = calloc(max_cpu_num, sizeof(int));
+	if (!cpunode_map) {
+		pr_err("%s: calloc failed\n", __func__);
+		goto out;
+	}
+
+	for (i = 0; i < max_cpu_num; i++)
+		cpunode_map[i] = -1;
+
+	return 0;
+out:
+	return -1;
+}
+
+int cpu__setup_cpunode_map(void)
+{
+	struct dirent *dent1, *dent2;
+	DIR *dir1, *dir2;
+	unsigned int cpu, mem;
+	char buf[PATH_MAX];
+	char path[PATH_MAX];
+	const char *mnt;
+
+	/* initialize globals */
+	if (init_cpunode_map())
+		return -1;
+
+	mnt = sysfs__mountpoint();
+	if (!mnt)
+		return 0;
+
+	snprintf(path, PATH_MAX, "%s/devices/system/node", mnt);
+	dir1 = opendir(path);
+	if (!dir1)
+		return 0;
+
+	/* walk tree and setup map */
+	while ((dent1 = readdir(dir1)) != NULL) {
+		if (dent1->d_type != DT_DIR ||
+		    sscanf(dent1->d_name, "node%u", &mem) < 1)
+			continue;
+
+		snprintf(buf, PATH_MAX, "%s/%s", path, dent1->d_name);
+		dir2 = opendir(buf);
+		if (!dir2)
+			continue;
+		while ((dent2 = readdir(dir2)) != NULL) {
+			if (dent2->d_type != DT_LNK ||
+			    sscanf(dent2->d_name, "cpu%u", &cpu) < 1)
+				continue;
+			cpunode_map[cpu] = mem;
+		}
+		closedir(dir2);
+	}
+	closedir(dir1);
+	return 0;
+}
diff --git a/tools/perf/util/cpumap.h b/tools/perf/util/cpumap.h
index b123bb9..61a6548 100644
--- a/tools/perf/util/cpumap.h
+++ b/tools/perf/util/cpumap.h
@@ -4,6 +4,9 @@
 #include <stdio.h>
 #include <stdbool.h>
 
+#include "perf.h"
+#include "util/debug.h"
+
 struct cpu_map {
 	int nr;
 	int map[];
@@ -46,4 +49,36 @@ static inline bool cpu_map__empty(const struct cpu_map *map)
 	return map ? map->map[0] == -1 : true;
 }
 
+int max_cpu_num;
+int max_node_num;
+int *cpunode_map;
+
+int cpu__setup_cpunode_map(void);
+
+static inline int cpu__max_node(void)
+{
+	if (unlikely(!max_node_num))
+		pr_debug("cpu_map not initialized\n");
+
+	return max_node_num;
+}
+
+static inline int cpu__max_cpu(void)
+{
+	if (unlikely(!max_cpu_num))
+		pr_debug("cpu_map not initialized\n");
+
+	return max_cpu_num;
+}
+
+static inline int cpu__get_node(int cpu)
+{
+	if (unlikely(cpunode_map == NULL)) {
+		pr_debug("cpu_map not initialized\n");
+		return -1;
+	}
+
+	return cpunode_map[cpu];
+}
+
 #endif /* __PERF_CPUMAP_H */
-- 
1.7.11.7

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