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tools/power turbostat: fix un-intended affinity of forked program

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Linux 3.4 included a modification to turbostat to
lower cross-call overhead by using scheduler affinity:

15aaa34654
(tools turbostat: reduce measurement overhead due to IPIs)

In the use-case where turbostat forks a child program,
that change had the un-intended side-effect of binding
the child to the last cpu in the system.

This change removed the binding before forking the child.

This is a back-port of a fix already included in turbostat v2.

Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Len Brown 2012-06-03 23:24:00 -04:00
parent f8f5701bda
commit d15cf7c129
1 changed files with 26 additions and 2 deletions
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28
tools/power/x86/turbostat/turbostat.c
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@ -73,8 +73,8 @@ int backwards_count;
char *progname; char *progname;
int num_cpus; int num_cpus;
cpu_set_t *cpu_mask; cpu_set_t *cpu_present_set, *cpu_mask;
size_t cpu_mask_size; size_t cpu_present_setsize, cpu_mask_size;
struct counters { struct counters {
unsigned long long tsc; /* per thread */ unsigned long long tsc; /* per thread */
@ -103,6 +103,12 @@ struct timeval tv_even;
struct timeval tv_odd; struct timeval tv_odd;
struct timeval tv_delta; struct timeval tv_delta;
int mark_cpu_present(int pkg, int core, int cpu)
{
CPU_SET_S(cpu, cpu_present_setsize, cpu_present_set);
return 0;
}
/* /*
* cpu_mask_init(ncpus) * cpu_mask_init(ncpus)
* *
@ -118,6 +124,18 @@ void cpu_mask_init(int ncpus)
} }
cpu_mask_size = CPU_ALLOC_SIZE(ncpus); cpu_mask_size = CPU_ALLOC_SIZE(ncpus);
CPU_ZERO_S(cpu_mask_size, cpu_mask); CPU_ZERO_S(cpu_mask_size, cpu_mask);
/*
* Allocate and initialize cpu_present_set
*/
cpu_present_set = CPU_ALLOC(ncpus);
if (cpu_present_set == NULL) {
perror("CPU_ALLOC");
exit(3);
}
cpu_present_setsize = CPU_ALLOC_SIZE(ncpus);
CPU_ZERO_S(cpu_present_setsize, cpu_present_set);
for_all_cpus(mark_cpu_present);
} }
void cpu_mask_uninit() void cpu_mask_uninit()
@ -125,6 +143,9 @@ void cpu_mask_uninit()
CPU_FREE(cpu_mask); CPU_FREE(cpu_mask);
cpu_mask = NULL; cpu_mask = NULL;
cpu_mask_size = 0; cpu_mask_size = 0;
CPU_FREE(cpu_present_set);
cpu_present_set = NULL;
cpu_present_setsize = 0;
} }
int cpu_migrate(int cpu) int cpu_migrate(int cpu)
@ -1047,6 +1068,9 @@ int fork_it(char **argv)
int retval; int retval;
pid_t child_pid; pid_t child_pid;
get_counters(cnt_even); get_counters(cnt_even);
/* clear affinity side-effect of get_counters() */
sched_setaffinity(0, cpu_present_setsize, cpu_present_set);
gettimeofday(&tv_even, (struct timezone *)NULL); gettimeofday(&tv_even, (struct timezone *)NULL);
child_pid = fork(); child_pid = fork();