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Re: [PATCH] Speedup various nptl/tst-mutex5 tests.
On 9/12/19 4:15 PM, Carlos O'Donell wrote:
On 9/12/19 8:16 AM, Stefan Liebler wrote:
each of these tests - tst-mutex5, tst-mutex5a, tst-mutexpi5
and tst-mutexpi5a - runs for 6s.
do_test_clock is called three times, which tries to lock the mutex
which times out after 2 seconds.
This patch reduces the timeout to 0.3 seconds which leads to a
runtime of roughly 0.9s for one tst-mutex5... invocation.
As the nptl tests run in sequence, this patch saves roughly 20s of
runtime for "make check".
* nptl/tst-mutex5.c (do_test_clock): Reduce timeout.
Why is it safe to wait 0.3 seconds instead of 2 seconds?
Is the timeout being used in place of synchronization elsewhere?
We need a comment specifying if it's safe to lower the timeout
The mutex is locked a few lines above and is not used to synchronize
elsewhere in the test. Instead the test checks that timedlock really
delays when returning with ETIMEDOUT.
So we need a measurable delay.
A further check within tst-mutex5.c is using timedlock on a non-locked
mutex in order to check that timedlock does not delay. There is the
/* Check that timedlock didn't delay. We use a limit of 0.1 secs. */
As <0.1s is used as "not delayed" we should use a timeout of >=0.1s
which is used as "delayed". To be a bit more safe, I propose 0.3s. But
I don't think that we need the original 2s. What's your suggestion?
What about this comment instead of "Wait xyz seconds":
/* Check that timedlock delays for a measurable amount of time
before returning with ETIMEDOUT. We use a delay of 0.3 secs. */