From fe0a5788624c8b8f113a35bbe4636e37f9321241 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Thu, 15 Oct 2020 14:58:48 +0200 Subject: tools/power/x86_energy_perf_policy: Read energy_perf_bias from sysfs ... and stop poking at the MSR directly. Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20201029190259.3476-4-bp@alien8.de --- .../x86_energy_perf_policy.c | 109 +++++++++++++++++++-- 1 file changed, 99 insertions(+), 10 deletions(-) (limited to 'tools/power/x86/x86_energy_perf_policy') diff --git a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c index 3fe1eed900d4..ad6aed1fabf8 100644 --- a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c +++ b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c @@ -91,6 +91,9 @@ unsigned int has_hwp_request_pkg; /* IA32_HWP_REQUEST_PKG */ unsigned int bdx_highest_ratio; +#define PATH_TO_CPU "/sys/devices/system/cpu/" +#define SYSFS_PATH_MAX 255 + /* * maintain compatibility with original implementation, but don't document it: */ @@ -668,6 +671,48 @@ int put_msr(int cpu, int offset, unsigned long long new_msr) return 0; } +static unsigned int read_sysfs(const char *path, char *buf, size_t buflen) +{ + ssize_t numread; + int fd; + + fd = open(path, O_RDONLY); + if (fd == -1) + return 0; + + numread = read(fd, buf, buflen - 1); + if (numread < 1) { + close(fd); + return 0; + } + + buf[numread] = '\0'; + close(fd); + + return (unsigned int) numread; +} + +static unsigned int write_sysfs(const char *path, char *buf, size_t buflen) +{ + ssize_t numwritten; + int fd; + + fd = open(path, O_WRONLY); + if (fd == -1) + return 0; + + numwritten = write(fd, buf, buflen - 1); + if (numwritten < 1) { + perror("write failed\n"); + close(fd); + return -1; + } + + close(fd); + + return (unsigned int) numwritten; +} + void print_hwp_cap(int cpu, struct msr_hwp_cap *cap, char *str) { if (cpu != -1) @@ -745,17 +790,61 @@ void write_hwp_request(int cpu, struct msr_hwp_request *hwp_req, unsigned int ms put_msr(cpu, msr_offset, msr); } +static int get_epb(int cpu) +{ + char path[SYSFS_PATH_MAX]; + char linebuf[3]; + char *endp; + long val; + + if (!has_epb) + return -1; + + snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu); + + if (!read_sysfs(path, linebuf, 3)) + return -1; + + val = strtol(linebuf, &endp, 0); + if (endp == linebuf || errno == ERANGE) + return -1; + + return (int)val; +} + +static int set_epb(int cpu, int val) +{ + char path[SYSFS_PATH_MAX]; + char linebuf[3]; + char *endp; + int ret; + + if (!has_epb) + return -1; + + snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu); + snprintf(linebuf, sizeof(linebuf), "%d", val); + + ret = write_sysfs(path, linebuf, 3); + if (ret <= 0) + return -1; + + val = strtol(linebuf, &endp, 0); + if (endp == linebuf || errno == ERANGE) + return -1; + + return (int)val; +} + int print_cpu_msrs(int cpu) { - unsigned long long msr; struct msr_hwp_request req; struct msr_hwp_cap cap; + int epb; - if (has_epb) { - get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr); - - printf("cpu%d: EPB %u\n", cpu, (unsigned int) msr); - } + epb = get_epb(cpu); + if (epb >= 0) + printf("cpu%d: EPB %u\n", cpu, (unsigned int) epb); if (!has_hwp) return 0; @@ -1038,15 +1127,15 @@ int enable_hwp_on_cpu(int cpu) int update_cpu_msrs(int cpu) { unsigned long long msr; - + int epb; if (update_epb) { - get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr); - put_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, new_epb); + epb = get_epb(cpu); + set_epb(cpu, new_epb); if (verbose) printf("cpu%d: ENERGY_PERF_BIAS old: %d new: %d\n", - cpu, (unsigned int) msr, (unsigned int) new_epb); + cpu, epb, (unsigned int) new_epb); } if (update_turbo) { -- cgit v1.2.3