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>
											
										 
										
											2010-03-10 20:36:09 +11:00
										 
									 
								 
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								#ifndef __PERF_CPUMAP_H
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								#define __PERF_CPUMAP_H
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								#include <stdio.h>
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								#include <stdbool.h>
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								struct cpu_map {
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									int nr;
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									int map[];
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								};
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								struct cpu_map *cpu_map__new(const char *cpu_list);
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								struct cpu_map *cpu_map__dummy_new(void);
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								void cpu_map__delete(struct cpu_map *map);
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								struct cpu_map *cpu_map__read(FILE *file);
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								size_t cpu_map__fprintf(struct cpu_map *map, FILE *fp);
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								int cpu_map__get_socket(struct cpu_map *map, int idx);
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								int cpu_map__get_core(struct cpu_map *map, int idx);
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								int cpu_map__build_socket_map(struct cpu_map *cpus, struct cpu_map **sockp);
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								int cpu_map__build_core_map(struct cpu_map *cpus, struct cpu_map **corep);
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								static inline int cpu_map__socket(struct cpu_map *sock, int s)
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								{
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									if (!sock || s > sock->nr || s < 0)
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										return 0;
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									return sock->map[s];
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								}
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								static inline int cpu_map__id_to_socket(int id)
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								{
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									return id >> 16;
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								}
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								static inline int cpu_map__id_to_cpu(int id)
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								{
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									return id & 0xffff;
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								}
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								static inline int cpu_map__nr(const struct cpu_map *map)
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								{
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									return map ? map->nr : 1;
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								}
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								static inline bool cpu_map__empty(const struct cpu_map *map)
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								{
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									return map ? map->map[0] == -1 : true;
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								}
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												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>
											
										 
										
											2010-03-10 20:36:09 +11:00
										 
									 
								 
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								#endif /* __PERF_CPUMAP_H */
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