Right. I found the following code snippet:
3715 /*
3716 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
3717 * that process accounting knows that this is a task in IO wait state.
3718 */
3719 void __sched io_schedule(void)
3720 {
3721 struct rq *rq = raw_rq();
3722
3723 delayacct_blkio_start();
3724 atomic_inc(&rq->nr_iowait);
3725 blk_flush_plug(current);
3726 current->in_iowait = 1;
3727 schedule();
3728 current->in_iowait = 0;
3729 atomic_dec(&rq->nr_iowait);
3730 delayacct_blkio_end();
3731 }
3732 EXPORT_SYMBOL(io_schedule);
3715 /*
3716 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
3717 * that process accounting knows that this is a task in IO wait state.
3718 */
3719 void __sched io_schedule(void)
3720 {
3721 struct rq *rq = raw_rq();
3722
3723 delayacct_blkio_start();
3724 atomic_inc(&rq->nr_iowait);
3725 blk_flush_plug(current);
3726 current->in_iowait = 1;
3727 schedule();
3728 current->in_iowait = 0;
3729 atomic_dec(&rq->nr_iowait);
3730 delayacct_blkio_end();
3731 }
3732 EXPORT_SYMBOL(io_schedule);
--
Regards,
shhuiw
shhuiw
At 2014-07-15 10:28:57, "Mohammad Merajul Islam Molla" <meraj.enigma@xxxxxxxxx> wrote: >Number of processes waiting for I/O to complete on a cpu? > >On Tue, Jul 15, 2014 at 8:22 AM, Andev <debiandev@xxxxxxxxx> wrote: >> On Mon, Jul 14, 2014 at 10:21 PM, Mohammad Merajul Islam Molla >> <meraj.enigma@xxxxxxxxx> wrote: >>> Hi Andev, >>> >>> Thanks for reply. I got the definition too. What I really want to know >>> is what this variable nr_iowait stands for? >>> Is it counting pending input/output on a cpu? >>> >>> >>> -- >>> - Meraj >>> >>> >>> >>> On Tue, Jul 15, 2014 at 8:07 AM, Andev <debiandev@xxxxxxxxx> wrote: >>>> On Mon, Jul 14, 2014 at 10:10 AM, Mohammad Merajul Islam Molla >>>> <meraj.enigma@xxxxxxxxx> wrote: >>>>> Hello, >>>>> >>>>> I was looking into the code of cpuidle menu governor and it uses a >>>>> function nr_iowait_cpu(int cpu). >>>>> I could not find out what this function does. >>>>> >>>>> Can someone please explain what nr_iowait_cpu(int cpu) and variant >>>>> nr_iowait() do? >>>>> >>>>> -- >> >> Now that is a better question. Try looking up what nr_iowait is. >> >>>> >>>> In all its glory: >>>> >>>> unsigned long nr_iowait_cpu(int cpu) >>>> { >>>> struct rq *this = cpu_rq(cpu); >>>> return atomic_read(&this->nr_iowait); >>>> } >>>> >>>> >>>>> Thanks, >>>>> -Meraj >>>>> >>>>> _______________________________________________ >>>>> Kernelnewbies mailing list >>>>> Kernelnewbies@xxxxxxxxxxxxxxxxx >>>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >>>> >>>> >>>> >>>> -- >>>> Andev >> >> >> >> -- >> Andev > >_______________________________________________ >Kernelnewbies mailing list >Kernelnewbies@xxxxxxxxxxxxxxxxx >http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
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