On Sat, Jul 10, 2021 at 11:45:19AM +0800, Patrick Star wrote:
> I saw flashrom process use too many cpu time when I use it to write
> flashchip.
> Then I strace the process, and found too many
> "clock_gettime(CLOCK_MONOTONIC...)" system call.
> And located it to udelay.c line 39, in function clock_usec_delay().
> So I replace the code with just usleep(), as below,
> static void clock_usec_delay(int usecs)
> {
> usleep(usecs);
> }
> And it still worked well, and use much less cpu time, and the time spend on
> erase&write a chip is basicly the same as before.
>
> Also I write image to a flashchip and read it out with the modified
> flashrom many times, and the read out results are always same as the
> original image.
>
> So why not use usleep() to save cpu time ?
>
usleep() will sleep a whole lot longer than a few microseconds when the
kernel isn't tickless; this could slow flashrom down drastically if for
instance a usleep() will always sleep at least 10 milliseconds on a 100
Hz tick-based kernel.
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