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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:

15aaa346
(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 <len.brown@intel.com>
parent f8f5701b

tools/power/x86/turbostat/turbostat.c

+26 −2
Original line number Original line Diff line number Diff line
@@ -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();