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

[ Upstream commit 0b8eb2ee9d ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Vineeth Vijayan 2020-06-18 16:42:45 +02:00 committed by Greg Kroah-Hartman
parent 2a8c6149a4
commit 1d63737b07
1 changed files with 5 additions and 0 deletions
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5
drivers/s390/cio/css.c
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@ -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;
}