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

Cyril Hrubis
2017-05-12T13:17:30Z

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...