Messages in this thread | | | From | Romain Izard <> | Date | Wed, 24 Feb 2016 17:44:59 +0100 | Subject | Re: [PATCH v2] clocksource: atmel-pit: register as a sched_clock |
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2016-02-24 17:20 GMT+01:00 Sylvain Rochet <sylvain.rochet@finsecur.com>: > Hi, > > On Wed, Feb 24, 2016 at 05:04:42PM +0100, Romain Izard wrote: >> Register the counter of the Periodic Interval Timer as a possible >> source for sched_clock. Keep the timer running even if the related >> clockevent is disabled. >> >> This provides a better precision than the jiffies-based default. The >> TCB clocksource does not work, as it is registered too late in the >> initialization sequence. > > I have mixed feelings about that, but this is probably just a > misunderstanding from my part. > My goal is to get a better precision on my printk and trace logs, because the precision of jiffies is really very bad compared to everything else I have encountered until now. But it looks like reading a timer is quite complicated on AT91...
> The PIT timer should not be used for systems with PM_SUSPEND enabled > and used because it takes ages to synchronize on resume, how does this > patch affect that ? > > Ref: commit ac34ad27fc ("clockevents: Do not suspend/resume if > unused")
So your advice would be to stay clear of the PIT, because it is (globally) useless.
I'll keep it in mind.
Best regards, -- Romain Izard
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