[LTP] [RFC] [PATCH] pselect01: Tune thresholds

Cyril Hrubis chrubis@suse.cz
Fri May 12 15:17:30 CEST 2017


Hi!
> Additionally, please keep in mind that on some architectures the
> time measured is based on the jiffies clock resolution which depends
> on the CONFIG_HZ value and results in a resolutions of e.g. 0.01, 
> 0.004, or 0.001 seconds which is way above the resolution you get
> on the x86 platform (with the TSC clock).
> 
> This testcase was failing for me on the parisc platform because of this inaccuracy.
> 
> Maybe the resolution of the CLOCK_MONOTONIC clock (which is basically used in this
> test) should be checked with clock_getres() and it's result included in the calculation?

Right, I've dusted off old pxa270 and indeed we cannot measure less than
20us interval there. But clock_getres() returns 10ms which is much more
than the actuall measured value...

-- 
Cyril Hrubis
chrubis@suse.cz


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