On Wednesday 07 April 2010 03:21:59 Mike Chan wrote:
> New file: cpuacct.cpufreq when CONFIG_CPU_FREQ_STATS is enabled.
>
> cpuacct.cpufreq reports the CPU time (nanoseconds) spent at each CPU frequency
>
> Maximum number of frequencies supported is 32. As future architectures are
> added that support more than 32 frequency levels, CPUFREQ_TABLE_MAX in sched.c
> needs to be updated.
Why is accounting of each frequency needed?
pcc-cpufreq driver can do every frequency in a range and supports hundreds of
different frequencies, thus it does not depend on CPU_FREQ_TABLE.
Would the average frequency be enough to track/account?
This would avoid the static interface of listing each available freq.
It would also count "boosted" frequency case which is avail on most recent
X86 cpus.
> Signed-off-by: Mike Chan <mike@xxxxxxxxxxx>
> ---
> Documentation/cgroups/cpuacct.txt | 3 +
> kernel/sched.c | 112 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 115 insertions(+), 0 deletions(-)
...
> static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
> @@ -9031,6 +9132,17 @@ static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
>
> for (; ca; ca = ca->parent) {
> u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
> +#ifdef CONFIG_CPU_FREQ_STAT
> + struct cpufreq_table *cpufreq_table =
> + per_cpu_ptr(ca->cpufreq_table, cpu);
> +
> + if (cpufreq_index > CPUFREQ_TABLE_MAX)
> + printk_once(KERN_WARNING "cpuacct_charge: "
> + "cpufreq_index: %d exceeds max table "
> + "size\n", cpufreq_index);
> + else
> + cpufreq_table->freq[cpufreq_index] += cputime;
> +#endif
Can the frequency change somewhere in the middle between cpuacct_charge is
called?
What guarantees that the task run at cpufreq_table->freq[cpufreq_index]
all the time?
Thomas
> *cpuusage += cputime;
> }
>
> --
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