Messages in this thread | | | Date | Tue, 19 Nov 2013 09:40:06 +0100 | From | Ingo Molnar <> | Subject | Re: [patch 1/3] sched_clock: document 4Mhz vs 1Mhz decision |
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* akpm@linux-foundation.org <akpm@linux-foundation.org> wrote:
> From: Stephen Boyd <sboyd@codeaurora.org> > Subject: sched_clock: document 4Mhz vs 1Mhz decision > > Bo Shen sent a patch to change this to 1Mhz instead of 4Mhz but according > to Russell King the use of 4Mhz was intentional. Add a comment to this > effect so that others don't try to change the code as well. > > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> > Cc: Bo Shen <voice.shen@atmel.com> > Cc: Russell King <rmk@arm.linux.org.uk> > Cc: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > --- > > kernel/time/sched_clock.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff -puN kernel/time/sched_clock.c~sched_clock-document-4mhz-vs-1mhz-decision kernel/time/sched_clock.c > --- a/kernel/time/sched_clock.c~sched_clock-document-4mhz-vs-1mhz-decision > +++ a/kernel/time/sched_clock.c > @@ -132,6 +132,10 @@ void __init sched_clock_register(u64 (*r > clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 3600); > > r = rate; > + /* > + * Use 4MHz instead of 1MHz so that things like 1.832Mhz show as > + * 1832Khz > + */ > if (r >= 4000000) { > r /= 1000000; > r_unit = 'M';
Instead of magic precision cutoff limits the better solution would be to simply display not just decimal part but also the first 3 digits of the fractional part:
1.123 Hz 990.134 kHz 1.832 MHz 12.314 GHz
etc. - then every number could be displayed in its natural unit without magic precision limits.
It would also be mostly self-documenting.
Thanks,
Ingo
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