提交 2ee507c4 编写于 作者: T Tim Chen 提交者: Herbert Xu

sched: Add function single_task_running to let a task check if it is the only task running on a cpu

This function will help an async task processing batched jobs from
workqueue decide if it wants to keep processing on more chunks of batched
work that can be delayed, or to accumulate more work for more efficient
batched processing later.

If no other tasks are running on the cpu, the batching process can take
advantgae of the available cpu cycles to a make decision to continue
processing the existing accumulated work to minimize delay,
otherwise it will yield.
Signed-off-by: NTim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
上级 bbb9a7dd
...@@ -167,6 +167,7 @@ extern int nr_threads; ...@@ -167,6 +167,7 @@ extern int nr_threads;
DECLARE_PER_CPU(unsigned long, process_counts); DECLARE_PER_CPU(unsigned long, process_counts);
extern int nr_processes(void); extern int nr_processes(void);
extern unsigned long nr_running(void); extern unsigned long nr_running(void);
extern bool single_task_running(void);
extern unsigned long nr_iowait(void); extern unsigned long nr_iowait(void);
extern unsigned long nr_iowait_cpu(int cpu); extern unsigned long nr_iowait_cpu(int cpu);
extern void get_iowait_load(unsigned long *nr_waiters, unsigned long *load); extern void get_iowait_load(unsigned long *nr_waiters, unsigned long *load);
......
...@@ -2366,6 +2366,18 @@ unsigned long nr_running(void) ...@@ -2366,6 +2366,18 @@ unsigned long nr_running(void)
return sum; return sum;
} }
/*
* Check if only the current task is running on the cpu.
*/
bool single_task_running(void)
{
if (cpu_rq(smp_processor_id())->nr_running == 1)
return true;
else
return false;
}
EXPORT_SYMBOL(single_task_running);
unsigned long long nr_context_switches(void) unsigned long long nr_context_switches(void)
{ {
int i; int i;
......
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