leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

tools/power turbostat: make fewer systems calls

Browse Source 
skip the open(2)/close(2) on each msr read
by keeping the /dev/cpu/*/msr files open.

The remaining read(2) is generally far fewer cycles
than the removed open(2) system call.

Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Len Brown 2016-02-26 20:51:02 -05:00
parent 58cc30a4e6
commit 36229897ba
1 changed files with 41 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
tools/power/x86/turbostat/turbostat.c
View File

@ -45,6 +45,7 @@
char *proc_stat = "/proc/stat";
FILE *outf;
int *fd_percpu;
struct timespec interval_ts = {5, 0};
unsigned int debug;
unsigned int rapl_joules;
@ -270,23 +271,34 @@ int cpu_migrate(int cpu)
else
return 0;
}
int get_msr(int cpu, off_t offset, unsigned long long *msr)
int get_msr_fd(int cpu)
{
ssize_t retval;
char pathname[32];
int fd;
fd = fd_percpu[cpu];
if (fd)
return fd;
sprintf(pathname, "/dev/cpu/%d/msr", cpu);
fd = open(pathname, O_RDONLY);
if (fd < 0)
err(-1, "%s open failed, try chown or chmod +r /dev/cpu/*/msr, or run as root", pathname);
retval = pread(fd, msr, sizeof *msr, offset);
close(fd);
fd_percpu[cpu] = fd;
return fd;
}
int get_msr(int cpu, off_t offset, unsigned long long *msr)
{
ssize_t retval;
retval = pread(get_msr_fd(cpu), msr, sizeof(*msr), offset);
if (retval != sizeof *msr)
err(-1, "%s offset 0x%llx read failed", pathname, (unsigned long long)offset);
err(-1, "msr %d offset 0x%llx read failed", cpu, (unsigned long long)offset);
return 0;
}
@ -1453,19 +1465,30 @@ dump_config_tdp(void)
fprintf(outf, "TDP_LEVEL=%d ", (unsigned int)(msr) & 0x3);
fprintf(outf, " lock=%d", (unsigned int)(msr >> 31) & 1);
fprintf(outf, ")\n");
get_msr(base_cpu, MSR_TURBO_ACTIVATION_RATIO, &msr);
fprintf(outf, "cpu%d: MSR_TURBO_ACTIVATION_RATIO: 0x%08llx (", base_cpu, msr);
fprintf(outf, "MAX_NON_TURBO_RATIO=%d", (unsigned int)(msr) & 0x7F);
fprintf(outf, " lock=%d", (unsigned int)(msr >> 31) & 1);
fprintf(outf, ")\n");
}
void free_fd_percpu(void)
{
int i;
for (i = 0; i < topo.max_cpu_num; ++i) {
if (fd_percpu[i] != 0)
close(fd_percpu[i]);
}
free(fd_percpu);
}
void free_all_buffers(void)
{
CPU_FREE(cpu_present_set);
cpu_present_set = NULL;
cpu_present_set = 0;
cpu_present_setsize = 0;
CPU_FREE(cpu_affinity_set);
cpu_affinity_set = NULL;
@ -1490,6 +1513,8 @@ void free_all_buffers(void)
free(output_buffer);
output_buffer = NULL;
outp = NULL;
free_fd_percpu();
}
/*
@ -2449,7 +2474,7 @@ int print_thermal(struct thread_data *t, struct core_data *c, struct pkg_data *p
return 0;
}
void print_power_limit_msr(int cpu, unsigned long long msr, char *label)
{
fprintf(outf, "cpu%d: %s: %sabled (%f Watts, %f sec, clamp %sabled)\n",
@ -3202,10 +3227,16 @@ void allocate_output_buffer()
if (outp == NULL)
err(-1, "calloc output buffer");
}
void allocate_fd_percpu(void)
{
fd_percpu = calloc(topo.max_cpu_num, sizeof(int));
if (fd_percpu == NULL)
err(-1, "calloc fd_percpu");
}
void setup_all_buffers(void)
{
topology_probe();
allocate_fd_percpu();
allocate_counters(&thread_even, &core_even, &package_even);
allocate_counters(&thread_odd, &core_odd, &package_odd);
allocate_output_buffer();