Commit d15cf7c1 authored by Len Brown's avatar Len Brown
Browse files

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

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


(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: default avatarLen Brown <>
parent f8f5701b
......@@ -73,8 +73,8 @@ int backwards_count;
char *progname;
int num_cpus;
cpu_set_t *cpu_mask;
size_t cpu_mask_size;
cpu_set_t *cpu_present_set, *cpu_mask;
size_t cpu_present_setsize, cpu_mask_size;
struct counters {
unsigned long long tsc; /* per thread */
......@@ -103,6 +103,12 @@ struct timeval tv_even;
struct timeval tv_odd;
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)
......@@ -118,6 +124,18 @@ void cpu_mask_init(int ncpus)
cpu_mask_size = CPU_ALLOC_SIZE(ncpus);
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) {
cpu_present_setsize = CPU_ALLOC_SIZE(ncpus);
CPU_ZERO_S(cpu_present_setsize, cpu_present_set);
void cpu_mask_uninit()
......@@ -125,6 +143,9 @@ void cpu_mask_uninit()
cpu_mask = NULL;
cpu_mask_size = 0;
cpu_present_set = NULL;
cpu_present_setsize = 0;
int cpu_migrate(int cpu)
......@@ -1047,6 +1068,9 @@ int fork_it(char **argv)
int retval;
pid_t child_pid;
/* clear affinity side-effect of get_counters() */
sched_setaffinity(0, cpu_present_setsize, cpu_present_set);
gettimeofday(&tv_even, (struct timezone *)NULL);
child_pid = fork();
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