From 36229897ba966bb0dc9e060222ff17b198252367 Mon Sep 17 00:00:00 2001 From: Len Brown Date: Fri, 26 Feb 2016 20:51:02 -0500 Subject: tools/power turbostat: make fewer systems calls 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 --- tools/power/x86/turbostat/turbostat.c | 51 ++++++++++++++++++++++++++++------- 1 file changed, 41 insertions(+), 10 deletions(-) (limited to 'tools') diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c index ad5bd5600467..2e47c2bc3e27 100644 --- a/tools/power/x86/turbostat/turbostat.c +++ b/tools/power/x86/turbostat/turbostat.c @@ -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(); -- cgit v1.2.3