tools turbostat: reduce measurement overhead due to IPIs

[linux-flexiantxendom0-3.2.10.git] / tools / power / x86 / turbostat / turbostat.c

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 6436d54..fa60872 100644 (file)
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -19,6 +19,7 @@
  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#define _GNU_SOURCE
 #include <stdio.h>
 #include <unistd.h>
 #include <sys/types.h>
@@ -32,6 +33,7 @@
 #include <dirent.h>
 #include <string.h>
 #include <ctype.h>
+#include <sched.h>
 
 #define MSR_TSC        0x10
 #define MSR_NEHALEM_PLATFORM_INFO      0xCE
@@ -72,6 +74,8 @@ char *progname;
 int need_reinitialize;
 
 int num_cpus;
+cpu_set_t *cpu_mask;
+size_t cpu_mask_size;
 
 struct counters {
        unsigned long long tsc;         /* per thread */
@@ -100,6 +104,40 @@ struct timeval tv_even;
 struct timeval tv_odd;
 struct timeval tv_delta;
 
+/*
+ * cpu_mask_init(ncpus)
+ *
+ * allocate and clear cpu_mask
+ * set cpu_mask_size
+ */
+void cpu_mask_init(int ncpus)
+{
+       cpu_mask = CPU_ALLOC(ncpus);
+       if (cpu_mask == NULL) {
+               perror("CPU_ALLOC");
+               exit(3);
+       }
+       cpu_mask_size = CPU_ALLOC_SIZE(ncpus);
+       CPU_ZERO_S(cpu_mask_size, cpu_mask);
+}
+
+void cpu_mask_uninit()
+{
+       CPU_FREE(cpu_mask);
+       cpu_mask = NULL;
+       cpu_mask_size = 0;
+}
+
+int cpu_migrate(int cpu)
+{
+       CPU_ZERO_S(cpu_mask_size, cpu_mask);
+       CPU_SET_S(cpu, cpu_mask_size, cpu_mask);
+       if (sched_setaffinity(0, cpu_mask_size, cpu_mask) == -1)
+               return -1;
+       else
+               return 0;
+}
+
 unsigned long long get_msr(int cpu, off_t offset)
 {
        ssize_t retval;
@@ -471,6 +509,11 @@ void compute_average(struct counters *delta, struct counters *avg)
 void get_counters(struct counters *cnt)
 {
        for ( ; cnt; cnt = cnt->next) {
+               if (cpu_migrate(cnt->cpu)) {
+                       need_reinitialize = 1;
+                       return;
+               }
+
                cnt->tsc = get_msr(cnt->cpu, MSR_TSC);
                if (do_nhm_cstates)
                        cnt->c3 = get_msr(cnt->cpu, MSR_CORE_C3_RESIDENCY);
@@ -752,6 +795,8 @@ void re_initialize(void)
        free_all_counters();
        num_cpus = for_all_cpus(alloc_new_counters);
        need_reinitialize = 0;
+       cpu_mask_uninit();
+       cpu_mask_init(num_cpus);
        printf("num_cpus is now %d\n", num_cpus);
 }
 
@@ -984,6 +1029,7 @@ void turbostat_init()
        check_super_user();
 
        num_cpus = for_all_cpus(alloc_new_counters);
+       cpu_mask_init(num_cpus);
 
        if (verbose)
                print_nehalem_info();