how long wait_for_completion_interruptible_timeout() blocks

anish singh anish198519851985 at
Thu Jun 20 02:07:54 EDT 2019

On Wed, Jun 19, 2019 at 10:47 PM Subhashini Rao Beerisetty <
subhashbeerisetty at> wrote:

> Hi All,
> I’ve two Linux systems, I tried to measure how long
> wait_for_completion_interruptible_timeout() blocked after completion
> is signaled by complete() call. I noticed two different results in
> both systems.
> In one system I noticed this duration in between 10 to 60 micro
> seconds, where as in other system  it is in between 20 to 500 micro
> seconds. I’d like to know what factors can affect this latency? Also,
> is there any solution to reduce this latency?

This is a problem which is fixed by RT Linux patches.
It is taking time as Linux is not RTOS and scheduler took time to put your
task in running state which is expected and depends on many factors: such
as load, interrupts and so on.

> Thanks,
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> Kernelnewbies mailing list
> Kernelnewbies at
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