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Date:	Sat, 29 Mar 2014 18:10:33 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Don Zickus <dzickus@...hat.com>
Cc:	acme@...stprotocols.net, LKML <linux-kernel@...r.kernel.org>,
	jmario@...hat.com, fowles@...each.com
Subject: Re: [PATCH 1/4] perf: Allow ability to map cpus to nodes easily

On Mon, Mar 24, 2014 at 03:32:54PM -0400, Don Zickus wrote:
> 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.
> 
> V3: simplify function names

some nits below, but I think Arnaldo should
see/check the namespace ;-)

thanks,
jirka

> 
> Signed-off-by: Don Zickus <dzickus@...hat.com>
> ---
>  tools/perf/util/cpumap.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++
>  tools/perf/util/cpumap.h |  35 ++++++++++++
>  2 files changed, 174 insertions(+)
> 
> diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
> index 7fe4994..2eb528e 100644
> --- a/tools/perf/util/cpumap.c
> +++ b/tools/perf/util/cpumap.c
> @@ -317,3 +317,142 @@ 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 __set_max_num(FILE *fp, int *max)
> +{
> +	int num;
> +	char buf[256];
> +
> +	num = fread(&buf, 1, sizeof(buf), fp);
> +	if (!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)
> +		return -1;
> +
> +	/* convert from 0-based to 1-based */
> +	(*max)++;
> +
> +	return 0;
> +}
> +
> +/* Determine highest possible cpu in the system for sparse allocation */
> +static void set_max_cpu_num(void)
> +{
> +	FILE *fp;
> +	int ret = -1;
> +
> +	/* set up default */
> +	max_cpu_num = 4096;
> +
> +	/* get the highest possible cpu number for a sparse allocation */
> +	fp = fopen("/sys/devices/system/cpu/possible", "r");
> +	if (!fp)
> +		goto out;
> +
> +	ret = __set_max_num(fp, &max_cpu_num);
> +
> +	fclose(fp);
> +
> +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)
> +{
> +	FILE *fp;
> +	int ret = -1;
> +
> +	/* set up default */
> +	max_node_num = 8;
> +
> +	/* get the highest possible cpu number for a sparse allocation */
> +	fp = fopen("/sys/devices/system/node/possible", "r");
> +	if (!fp)
> +		goto out;

any reason why not put fopen/fclose into __set_max_num ?

also looks like 'get_max_num' would fit better for __set_max_num ;-)

> +
> +	ret = __set_max_num(fp, &max_node_num);
> +
> +	fclose(fp);
> +	

^^^ whitespace

> +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;
> +}
> +
> +#define PATH_SYS_NODE   "/sys/devices/system/node"
> +
> +int cpu__setup_cpunode_map(void)
> +{
> +	struct dirent *dent1, *dent2;
> +	DIR *dir1, *dir2;
> +	unsigned int cpu, mem;
> +	char buf[PATH_MAX];
> +
> +	/* initialize globals */
> +	if (init_cpunode_map())
> +		return -1;
> +
> +	dir1 = opendir(PATH_SYS_NODE);
> +	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_SYS_NODE, 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;
> +}
> +

^^^ white space

> diff --git a/tools/perf/util/cpumap.h b/tools/perf/util/cpumap.h
> index b123bb9..ce3c5a0 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 initiailzed\n");

typo: initialized

> +
> +	return max_node_num;
> +}
> +
> +static inline int cpu__max_cpu(void)
> +{
> +	if (unlikely(!max_cpu_num))
> +		pr_debug("cpu_map not initiailzed\n");

ditto

> +
> +	return max_cpu_num;
> +}
> +
> +static inline int cpu__get_node(int cpu)
> +{
> +	if (unlikely(cpunode_map == NULL)) {
> +		pr_debug("cpu_map not initialized\n");

ditto

> +		return -1;
> +	}
> +
> +	return cpunode_map[cpu];
> +}
> +
>  #endif /* __PERF_CPUMAP_H */
> -- 
> 1.7.11.7
> 
--
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