tools/power turbostat: allow running without cpu0

Linux-3.7 added CONFIG_BOOTPARAM_HOTPLUG_CPU0,
allowing systems to offline cpu0.

But when cpu0 is offline, turbostat will not run:

 # turbostat ls
turbostat: no /dev/cpu/0/msr

This patch replaces the hard-coded use of cpu0 in turbostat
with the current cpu, allowing it to run without a cpu0.

Fewer cross-calls may also be needed due to use of current cpu,
though this hard-coding was used only for the --debug preamble.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 31 insertions, 15 deletions

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index f92211e9e70c..68e77fdd4c04 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -92,6 +92,7 @@ unsigned int do_gfx_perf_limit_reasons;
 unsigned int do_ring_perf_limit_reasons;
 unsigned int crystal_hz;
 unsigned long long tsc_hz;
+int base_cpu;
 
 #define RAPL_PKG                (1 << 0)
                                         /* 0x610 MSR_PKG_POWER_LIMIT */
@@ -1154,7 +1155,7 @@ dump_nhm_platform_info(void)
         unsigned long long msr;
         unsigned int ratio;
 
-        get_msr(0, MSR_NHM_PLATFORM_INFO, &msr);
+        get_msr(base_cpu, MSR_NHM_PLATFORM_INFO, &msr);
 
         fprintf(stderr, "cpu0: MSR_NHM_PLATFORM_INFO: 0x%08llx\n", msr);
 
@@ -1166,7 +1167,7 @@ dump_nhm_platform_info(void)
         fprintf(stderr, "%d * %.0f = %.0f MHz base frequency\n",
                 ratio, bclk, ratio * bclk);
 
-        get_msr(0, MSR_IA32_POWER_CTL, &msr);
+        get_msr(base_cpu, MSR_IA32_POWER_CTL, &msr);
         fprintf(stderr, "cpu0: MSR_IA32_POWER_CTL: 0x%08llx (C1E auto-promotion: %sabled)\n",
                 msr, msr & 0x2 ? "EN" : "DIS");
 
@@ -1179,7 +1180,7 @@ dump_hsw_turbo_ratio_limits(void)
         unsigned long long msr;
         unsigned int ratio;
 
-        get_msr(0, MSR_TURBO_RATIO_LIMIT2, &msr);
+        get_msr(base_cpu, MSR_TURBO_RATIO_LIMIT2, &msr);
 
         fprintf(stderr, "cpu0: MSR_TURBO_RATIO_LIMIT2: 0x%08llx\n", msr);
 
@@ -1201,7 +1202,7 @@ dump_ivt_turbo_ratio_limits(void)
         unsigned long long msr;
         unsigned int ratio;
 
-        get_msr(0, MSR_TURBO_RATIO_LIMIT1, &msr);
+        get_msr(base_cpu, MSR_TURBO_RATIO_LIMIT1, &msr);
 
         fprintf(stderr, "cpu0: MSR_TURBO_RATIO_LIMIT1: 0x%08llx\n", msr);
 
@@ -1253,7 +1254,7 @@ dump_nhm_turbo_ratio_limits(void)
         unsigned long long msr;
         unsigned int ratio;
 
-        get_msr(0, MSR_TURBO_RATIO_LIMIT, &msr);
+        get_msr(base_cpu, MSR_TURBO_RATIO_LIMIT, &msr);
 
         fprintf(stderr, "cpu0: MSR_TURBO_RATIO_LIMIT: 0x%08llx\n", msr);
 
@@ -1309,7 +1310,7 @@ dump_knl_turbo_ratio_limits(void)
         int delta_ratio;
         int i;
 
-        get_msr(0, MSR_NHM_TURBO_RATIO_LIMIT, &msr);
+        get_msr(base_cpu, MSR_NHM_TURBO_RATIO_LIMIT, &msr);
 
         fprintf(stderr, "cpu0: MSR_NHM_TURBO_RATIO_LIMIT: 0x%08llx\n",
         msr);
@@ -1365,7 +1366,7 @@ dump_nhm_cst_cfg(void)
 {
         unsigned long long msr;
 
-        get_msr(0, MSR_NHM_SNB_PKG_CST_CFG_CTL, &msr);
+        get_msr(base_cpu, MSR_NHM_SNB_PKG_CST_CFG_CTL, &msr);
 
 #define SNB_C1_AUTO_UNDEMOTE              (1UL << 27)
 #define SNB_C3_AUTO_UNDEMOTE              (1UL << 28)
@@ -1694,8 +1695,10 @@ restart:
 void check_dev_msr()
 {
         struct stat sb;
+        char pathname[32];
 
-        if (stat("/dev/cpu/0/msr", &sb))
+        sprintf(pathname, "/dev/cpu/%d/msr", base_cpu);
+        if (stat(pathname, &sb))
                 if (system("/sbin/modprobe msr > /dev/null 2>&1"))
                         err(-5, "no /dev/cpu/0/msr, Try \"# modprobe msr\" ");
 }
@@ -1708,6 +1711,7 @@ void check_permissions()
         cap_user_data_t cap_data = &cap_data_data;
         extern int capget(cap_user_header_t hdrp, cap_user_data_t datap);
         int do_exit = 0;
+        char pathname[32];
 
         /* check for CAP_SYS_RAWIO */
         cap_header->pid = getpid();
@@ -1722,7 +1726,8 @@ void check_permissions()
         }
 
         /* test file permissions */
-        if (euidaccess("/dev/cpu/0/msr", R_OK)) {
+        sprintf(pathname, "/dev/cpu/%d/msr", base_cpu);
+        if (euidaccess(pathname, R_OK)) {
                 do_exit++;
                 warn("/dev/cpu/0/msr open failed, try chown or chmod +r /dev/cpu/*/msr");
         }
@@ -1804,7 +1809,7 @@ int probe_nhm_msrs(unsigned int family, unsigned int model)
         default:
                 return 0;
         }
-        get_msr(0, MSR_NHM_SNB_PKG_CST_CFG_CTL, &msr);
+        get_msr(base_cpu, MSR_NHM_SNB_PKG_CST_CFG_CTL, &msr);
 
         pkg_cstate_limit = pkg_cstate_limits[msr & 0xF];
 
@@ -2043,7 +2048,7 @@ double get_tdp(model)
         unsigned long long msr;
 
         if (do_rapl & RAPL_PKG_POWER_INFO)
-                if (!get_msr(0, MSR_PKG_POWER_INFO, &msr))
+                if (!get_msr(base_cpu, MSR_PKG_POWER_INFO, &msr))
                         return ((msr >> 0) & RAPL_POWER_GRANULARITY) * rapl_power_units;
 
         switch (model) {
@@ -2126,7 +2131,7 @@ void rapl_probe(unsigned int family, unsigned int model)
         }
 
         /* units on package 0, verify later other packages match */
-        if (get_msr(0, MSR_RAPL_POWER_UNIT, &msr))
+        if (get_msr(base_cpu, MSR_RAPL_POWER_UNIT, &msr))
                 return;
 
         rapl_power_units = 1.0 / (1 << (msr & 0xF));
@@ -2471,7 +2476,7 @@ double slm_bclk(void)
         unsigned int i;
         double freq;
 
-        if (get_msr(0, MSR_FSB_FREQ, &msr))
+        if (get_msr(base_cpu, MSR_FSB_FREQ, &msr))
                 fprintf(stderr, "SLM BCLK: unknown\n");
 
         i = msr & 0xf;
@@ -2539,7 +2544,7 @@ int set_temperature_target(struct thread_data *t, struct core_data *c, struct pk
         if (!do_nhm_platform_info)
                 goto guess;
 
-        if (get_msr(0, MSR_IA32_TEMPERATURE_TARGET, &msr))
+        if (get_msr(base_cpu, MSR_IA32_TEMPERATURE_TARGET, &msr))
                 goto guess;
 
         target_c_local = (msr >> 16) & 0xFF;
@@ -2913,13 +2918,24 @@ void setup_all_buffers(void)
         for_all_proc_cpus(initialize_counters);
 }
 
+void set_base_cpu(void)
+{
+        base_cpu = sched_getcpu();
+        if (base_cpu < 0)
+                err(-ENODEV, "No valid cpus found");
+
+        if (debug > 1)
+                fprintf(stderr, "base_cpu = %d\n", base_cpu);
+}
+
 void turbostat_init()
 {
+        setup_all_buffers();
+        set_base_cpu();
         check_dev_msr();
         check_permissions();
         process_cpuid();
 
-        setup_all_buffers();
 
         if (debug)
                 for_all_cpus(print_epb, ODD_COUNTERS);