Sched-tools May 2016

sched-tools@lists.linaro.org

2 participants
1 discussions

Re: [Sched-tools] [PATCH] idlestat: Initialize CPU's idle state properly

by Vincent Guittot

+ adding sched-tools mailing list On 17 May 2016 at 03:02, Leo Yan <leo.yan(a)linaro.org> wrote: > In current code the CPU's idle state cpufreq_pstates::idle is initialized > to '-1'; and until parse first "cpu_idle" event for the CPU then set CPU's > idle state to '0' or '1' corresponding to active or idle. This will cause > error for P-state's statistics: from the beginning to first "cpu_idle" > event, during this period the CPU's idle state is '-1' so function > cpu_change_pstate() will always think it's first update and finally abandon > previous time. > > This will introduce very big error if the CPU is always running and never > run into idle state. So this patch is to fix this issue by initialize CPU's > idle state before parse P-state and C-state's time. Initialize CPU's idle > state according to first cpu_idle log: > - If the CPU first cpu_idle state is '-1', that means from the beginning > the CPU is stayed on idle state; > - If the CPU first cpu_idle state is other value, means the CPU is active. > > Signed-off-by: Leo Yan <leo.yan(a)linaro.org> > --- > tracefile_idlestat.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 51 insertions(+) > > diff --git a/tracefile_idlestat.c b/tracefile_idlestat.c > index 3430693..fb0b3d8 100644 > --- a/tracefile_idlestat.c > +++ b/tracefile_idlestat.c > @@ -152,6 +152,55 @@ int load_text_data_line(char *buffer, struct cpuidle_datas *datas, char *format, > return get_wakeup_irq(datas, buffer); > } > > +/** > + * init_cpu_idle_state - Init CPU's idle state according to first cpu_idle log. > + * For a specific cpu_idle event, its state is '-1' then that means from the > + * beginning the CPU is stayed on idle state; Otherwise means the CPU is active. > + * So initilize per-CPU idle flag to get more accurate time. > + * > + * @datas: structure for P-state and C-state's statistics > + * @f: the file handle of the idlestat trace file > + */ > +void init_cpu_idle_state(struct cpuidle_datas *datas, FILE *f) > +{ > + struct cpufreq_pstates *ps; > + unsigned int state, freq, cpu; > + double time; > + char buffer[BUFSIZE]; > + > + do { > + if (strstr(buffer, "cpu_idle")) { > + if (sscanf(buffer, TRACE_FORMAT, &time, &state, &cpu) > + != 3) { > + fprintf(stderr, "warning: Unrecognized cpuidle " > + "record. The result of analysis might " > + "be wrong.\n"); > + return -1; > + } > + } > + > + ps = &(datas->pstates[cpu]); > + > + /* CPU's state has been initialized, skip it */ > + if (ps->idle != -1) > + continue; > + > + /* > + * The CPU's first cpu_idle is '-1', means CPU is staying in > + * idle state and exit from idle until first cpu_idle event. > + * Otherwise, means the CPU is active at beginning. > + */ > + if (state == -1) > + ps->idle = 1; > + else > + ps->idle = 0; > + > + } while (fgets(buffer, BUFSIZE, f)); > + > + /* After traverse file, reset offset */ > + fseek(f, 0, SEEK_SET); > +} > + > void load_text_data_lines(FILE *f, char *buffer, struct cpuidle_datas *datas) > { > double begin = 0, end = 0; > @@ -159,6 +208,8 @@ void load_text_data_lines(FILE *f, char *buffer, struct cpuidle_datas *datas) > > setup_topo_states(datas); > > + init_cpu_idle_state(datas, f); > + > do { > if (load_text_data_line(buffer, datas, TRACE_FORMAT, > &begin, &end, &start) != -1) { > -- > 1.9.1 >

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Sched-tools May 2016