Messages in this thread | | | Subject | Re: [PATCH v2 5/6] KVM-GST: adjust scheduler cpu power | From | Peter Zijlstra <> | Date | Mon, 31 Jan 2011 12:25:20 +0100 |
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On Fri, 2011-01-28 at 14:52 -0500, Glauber Costa wrote:
> +#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING > +static DEFINE_PER_CPU(u64, cpu_steal_time); > + > +#ifndef CONFIG_64BIT > +static DEFINE_PER_CPU(seqcount_t, steal_time_seq); > + > +static inline void steal_time_write_begin(void) > +{ > + __this_cpu_inc(steal_time_seq.sequence); > + smp_wmb(); > +} > + > +static inline void steal_time_write_end(void) > +{ > + smp_wmb(); > + __this_cpu_inc(steal_time_seq.sequence); > +} > + > +static inline u64 steal_time_read(int cpu) > +{ > + u64 steal_time; > + unsigned seq; > + > + do { > + seq = read_seqcount_begin(&per_cpu(steal_time_seq, cpu)); > + steal_time = per_cpu(cpu_steal_time, cpu); > + } while (read_seqcount_retry(&per_cpu(steal_time_seq, cpu), seq)); > + > + return steal_time; > +} > +#else /* CONFIG_64BIT */ > +static inline void steal_time_write_begin(void) > +{ > +} > + > +static inline void steal_time_write_end(void) > +{ > +} > + > +static inline u64 steal_time_read(int cpu) > +{ > + return per_cpu(cpu_steal_time, cpu); > +}
> @@ -3536,6 +3592,11 @@ static int touch_steal_time(int is_idle) > > if (st) { > account_steal_time(st); > +#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING > + steal_time_write_begin(); > + __this_cpu_add(cpu_steal_time, steal); > + steal_time_write_end(); > +#endif > return 1; > } > return 0;
Why replicate all logic you've already got in patch 4? That too is reading steal time in a loop in kvm_account_steal_time(), why not extend that interface to take a cpu argument and be done with it?
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