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); -- Regards, shhuiw At 2014-07-15 10:28:57, "Mohammad Merajul Islam Molla" <meraj.enigma@gmail.com> wrote:
Number of processes waiting for I/O to complete on a cpu?
On Tue, Jul 15, 2014 at 8:22 AM, Andev <debiandev@gmail.com> wrote:
On Mon, Jul 14, 2014 at 10:21 PM, Mohammad Merajul Islam Molla <meraj.enigma@gmail.com> 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@gmail.com> wrote:
On Mon, Jul 14, 2014 at 10:10 AM, Mohammad Merajul Islam Molla <meraj.enigma@gmail.com> 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
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