perf tools: Allow ability to map cpus to nodes easily

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.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1396896924-129847-2-git-send-email-dzickus@redhat.com
[ Removing out label code in init_cpunode_map ]
[ Adding check for snprintf error ]
[ Removing unneeded returns ]
Signed-off-by: Jiri Olsa <jolsa@redhat.com>

2 files changed, 195 insertions, 0 deletions

diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index 7fe4994eeb63..526da022b3c4 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -317,3 +317,163 @@ 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 */
+        ret = snprintf(path, PATH_MAX, "%s/devices/system/cpu/kernel_max", mnt);
+        if (ret == PATH_MAX) {
+                pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
+                goto out;
+        }
+
+        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);
+}
+
+/* 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 */
+        ret = snprintf(path, PATH_MAX, "%s/devices/system/node/possible", mnt);
+        if (ret == PATH_MAX) {
+                pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
+                goto out;
+        }
+
+        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);
+}
+
+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__);
+                return -1;
+        }
+
+        for (i = 0; i < max_cpu_num; i++)
+                cpunode_map[i] = -1;
+
+        return 0;
+}
+
+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;
+        int n;
+
+        /* initialize globals */
+        if (init_cpunode_map())
+                return -1;
+
+        mnt = sysfs__mountpoint();
+        if (!mnt)
+                return 0;
+
+        n = snprintf(path, PATH_MAX, "%s/devices/system/node", mnt);
+        if (n == PATH_MAX) {
+                pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
+                return -1;
+        }
+
+        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;
+
+                n = snprintf(buf, PATH_MAX, "%s/%s", path, dent1->d_name);
+                if (n == PATH_MAX) {
+                        pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
+                        continue;
+                }
+
+                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 b123bb9d6f55..61a654849002 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 */