Commit 0b8eb2ee authored Jun 18, 2020 by Vineeth Vijayan Committed by Heiko Carstens Aug 17, 2020

s390/cio: add cond_resched() in the slow_eval_known_fn() loop



The scanning through subchannels during the time of an event could
take significant amount of time in case of platforms with lots of
known subchannels. This might result in higher scheduling latencies
for other tasks especially on systems with a single CPU. Add
cond_resched() call, as the loop in slow_eval_known_fn() can be
executed for a longer duration.

Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

parent 9123e3a7

drivers/s390/cio/css.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -677,6 +677,11 @@ static int slow_eval_known_fn(struct subchannel sch, void data)
		rc = css_evaluate_known_subchannel(sch, 1);
		if (rc == -EAGAIN)
		css_schedule_eval(sch->schid);
		/*
		* The loop might take long time for platforms with lots of
		* known devices. Allow scheduling here.
		*/
		cond_resched();
		}
		return 0;
		}

Admin message