Root/tools/perf/util/cpumap.c

1#include "util.h"
2#include "../perf.h"
3#include "cpumap.h"
4#include <assert.h>
5#include <stdio.h>
6
7int cpumap[MAX_NR_CPUS];
8
9static int default_cpu_map(void)
10{
11    int nr_cpus, i;
12
13    nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
14    assert(nr_cpus <= MAX_NR_CPUS);
15    assert((int)nr_cpus >= 0);
16
17    for (i = 0; i < nr_cpus; ++i)
18        cpumap[i] = i;
19
20    return nr_cpus;
21}
22
23int read_cpu_map(void)
24{
25    FILE *onlnf;
26    int nr_cpus = 0;
27    int n, cpu, prev;
28    char sep;
29
30    onlnf = fopen("/sys/devices/system/cpu/online", "r");
31    if (!onlnf)
32        return default_cpu_map();
33
34    sep = 0;
35    prev = -1;
36    for (;;) {
37        n = fscanf(onlnf, "%u%c", &cpu, &sep);
38        if (n <= 0)
39            break;
40        if (prev >= 0) {
41            assert(nr_cpus + cpu - prev - 1 < MAX_NR_CPUS);
42            while (++prev < cpu)
43                cpumap[nr_cpus++] = prev;
44        }
45        assert (nr_cpus < MAX_NR_CPUS);
46        cpumap[nr_cpus++] = cpu;
47        if (n == 2 && sep == '-')
48            prev = cpu;
49        else
50            prev = -1;
51        if (n == 1 || sep == '\n')
52            break;
53    }
54    fclose(onlnf);
55    if (nr_cpus > 0)
56        return nr_cpus;
57
58    return default_cpu_map();
59}
60

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