diff options
| -rw-r--r-- | tools/power/x86/turbostat/turbostat.8 | 66 | ||||
| -rw-r--r-- | tools/power/x86/turbostat/turbostat.c | 47 |
2 files changed, 68 insertions, 45 deletions
diff --git a/tools/power/x86/turbostat/turbostat.8 b/tools/power/x86/turbostat/turbostat.8 index 56bfb52..9b95069 100644 --- a/tools/power/x86/turbostat/turbostat.8 +++ b/tools/power/x86/turbostat/turbostat.8 @@ -12,16 +12,16 @@ turbostat \- Report processor frequency and idle statistics .RB [ "\-i interval_sec" ] .SH DESCRIPTION \fBturbostat \fP reports processor topology, frequency, -idle power-state statistics, temperature and power on modern X86 processors. -Either \fBcommand\fP is forked and statistics are printed -upon its completion, or statistics are printed periodically. - -\fBturbostat \fP -must be run on root, and -minimally requires that the processor -supports an "invariant" TSC, plus the APERF and MPERF MSRs. -Additional information is reported depending on hardware counter support. - +idle power-state statistics, temperature and power on X86 processors. +There are two ways to invoke turbostat. +The first method is to supply a +\fBcommand\fP, which is forked and statistics are printed +upon its completion. +The second method is to omit the command, +and turbodstat will print statistics every 5 seconds. +The 5-second interval can changed using the -i option. + +Some information is not availalbe on older processors. .SS Options The \fB-p\fP option limits output to the 1st thread in 1st core of each package. .PP @@ -130,12 +130,13 @@ cpu3: MSR_IA32_THERM_STATUS: 0x884e0000 (27 C +/- 1) ... .fi The \fBmax efficiency\fP frequency, a.k.a. Low Frequency Mode, is the frequency -available at the minimum package voltage. The \fBTSC frequency\fP is the nominal -maximum frequency of the processor if turbo-mode were not available. This frequency +available at the minimum package voltage. The \fBTSC frequency\fP is the base +frequency of the processor -- this should match the brand string +in /proc/cpuinfo. This base frequency should be sustainable on all CPUs indefinitely, given nominal power and cooling. The remaining rows show what maximum turbo frequency is possible -depending on the number of idle cores. Note that this information is -not available on all processors. +depending on the number of idle cores. Note that not all information is +available on all processors. .SH FORK EXAMPLE If turbostat is invoked with a command, it will fork that command and output the statistics gathered when the command exits. @@ -176,6 +177,11 @@ not including any non-busy idle time. .B "turbostat " must be run as root. +Alternatively, non-root users can be enabled to run turbostat this way: + +# setcap cap_sys_rawio=ep ./turbostat + +# chmod +r /dev/cpu/*/msr .B "turbostat " reads hardware counters, but doesn't write them. @@ -184,15 +190,33 @@ multiple invocations of itself. \fBturbostat \fP may work poorly on Linux-2.6.20 through 2.6.29, -as \fBacpi-cpufreq \fPperiodically cleared the APERF and MPERF +as \fBacpi-cpufreq \fPperiodically cleared the APERF and MPERF MSRs in those kernels. -If the TSC column does not make sense, then -the other numbers will also make no sense. -Turbostat is lightweight, and its data collection is not atomic. -These issues are usually caused by an extremely short measurement -interval (much less than 1 second), or system activity that prevents -turbostat from being able to run on all CPUS to quickly collect data. +AVG_MHz = APERF_delta/measurement_interval. This is the actual +number of elapsed cycles divided by the entire sample interval -- +including idle time. Note that this calculation is resiliant +to systems lacking a non-stop TSC. + +TSC_MHz = TSC_delta/measurement_interval. +On a system with an invariant TSC, this value will be constant +and will closely match the base frequency value shown +in the brand string in /proc/cpuinfo. On a system where +the TSC stops in idle, TSC_MHz will drop +below the processor's base frequency. + +%Busy = MPERF_delta/TSC_delta + +Bzy_MHz = TSC_delta/APERF_delta/MPERF_delta/measurement_interval + +Note that these calculations depend on TSC_delta, so they +are not reliable during intervals when TSC_MHz is not running at the base frequency. + +Turbostat data collection is not atomic. +Extremely short measurement intervals (much less than 1 second), +or system activity that prevents turbostat from being able +to run on all CPUS to quickly collect data, will result in +inconsistent results. The APERF, MPERF MSRs are defined to count non-halted cycles. Although it is not guaranteed by the architecture, turbostat assumes diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c index b654b64..a02c02f 100644 --- a/tools/power/x86/turbostat/turbostat.c +++ b/tools/power/x86/turbostat/turbostat.c @@ -673,24 +673,26 @@ delta_thread(struct thread_data *new, struct thread_data *old, old->c1 = new->c1 - old->c1; - if ((new->aperf > old->aperf) && (new->mperf > old->mperf)) { - old->aperf = new->aperf - old->aperf; - old->mperf = new->mperf - old->mperf; - } else { + if (has_aperf) { + if ((new->aperf > old->aperf) && (new->mperf > old->mperf)) { + old->aperf = new->aperf - old->aperf; + old->mperf = new->mperf - old->mperf; + } else { - if (!aperf_mperf_unstable) { - fprintf(stderr, "%s: APERF or MPERF went backwards *\n", progname); - fprintf(stderr, "* Frequency results do not cover entire interval *\n"); - fprintf(stderr, "* fix this by running Linux-2.6.30 or later *\n"); + if (!aperf_mperf_unstable) { + fprintf(stderr, "%s: APERF or MPERF went backwards *\n", progname); + fprintf(stderr, "* Frequency results do not cover entire interval *\n"); + fprintf(stderr, "* fix this by running Linux-2.6.30 or later *\n"); - aperf_mperf_unstable = 1; + aperf_mperf_unstable = 1; + } + /* + * mperf delta is likely a huge "positive" number + * can not use it for calculating c0 time + */ + skip_c0 = 1; + skip_c1 = 1; } - /* - * mperf delta is likely a huge "positive" number - * can not use it for calculating c0 time - */ - skip_c0 = 1; - skip_c1 = 1; } @@ -2244,14 +2246,11 @@ void check_cpuid() has_epb = ecx & (1 << 3); if (verbose) - fprintf(stderr, "CPUID(6): %s%s%s%s\n", - has_aperf ? "APERF" : "No APERF!", - do_dts ? ", DTS" : "", - do_ptm ? ", PTM": "", - has_epb ? ", EPB": ""); - - if (!has_aperf) - errx(-1, "No APERF"); + fprintf(stderr, "CPUID(6): %sAPERF, %sDTS, %sPTM, %sEPB\n", + has_aperf ? "" : "No ", + do_dts ? "" : "No ", + do_ptm ? "" : "No ", + has_epb ? "" : "No "); do_nhm_platform_info = do_nhm_cstates = do_smi = has_nhm_msrs(family, model); do_snb_cstates = has_snb_msrs(family, model); @@ -2632,7 +2631,7 @@ int main(int argc, char **argv) cmdline(argc, argv); if (verbose) - fprintf(stderr, "turbostat v3.8 14-Aug 2014" + fprintf(stderr, "turbostat v3.9 23-Jan, 2015" " - Len Brown <lenb@kernel.org>\n"); turbostat_init(); |