Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait condition
From: Steve Muckle <hidden>
Date: 2016-08-02 01:23:42
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lkml
On Mon, Aug 01, 2016 at 01:37:23AM +0200, Rafael J. Wysocki wrote: ...
For this purpose, define a new cpufreq_update_util() flag UUF_IO and modify enqueue_task_fair() to pass that flag to cpufreq_update_util() in the in_iowait case. That generally requires cpufreq_update_util() to be called directly from there, because update_load_avg() is not likely to be invoked in that case.
I didn't follow why the cpufreq hook won't likely be called if in_iowait is set? AFAICS update_load_avg() gets called in the second loop and calls update_cfs_rq_load_avg (triggers the hook).
quoted hunk ↗ jump to hunk
Signed-off-by: Rafael J. Wysocki <redacted> --- include/linux/sched.h | 1 + kernel/sched/fair.c | 8 ++++++++ 2 files changed, 9 insertions(+) Index: linux-pm/kernel/sched/fair.c ===================================================================--- linux-pm.orig/kernel/sched/fair.c +++ linux-pm/kernel/sched/fair.c@@ -4459,6 +4459,14 @@ enqueue_task_fair(struct rq *rq, struct struct cfs_rq *cfs_rq; struct sched_entity *se = &p->se; + /* + * If in_iowait is set, it is likely that the loops below will not + * trigger any cpufreq utilization updates, so do it here explicitly + * with the IO flag passed. + */ + if (p->in_iowait) + cpufreq_update_util(rq, UUF_IO); + for_each_sched_entity(se) { if (se->on_rq) break;Index: linux-pm/include/linux/sched.h ===================================================================--- linux-pm.orig/include/linux/sched.h +++ linux-pm/include/linux/sched.h@@ -3376,6 +3376,7 @@ static inline unsigned long rlimit_max(u } #define UUF_RT 0x01 +#define UUF_IO 0x02 #ifdef CONFIG_CPU_FREQ struct update_util_data {
thanks, Steve