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From: viresh.kumar@linaro.org (Viresh Kumar)
To: linux-arm-kernel@lists.infradead.org
Subject: schedule_timeout sleeps too long after dividing CPU frequency
Date: Thu, 14 May 2015 17:24:56 +0530	[thread overview]
Message-ID: <20150514115456.GB23999@linux> (raw)
In-Reply-To: <5554858A.9010207@free.fr>

On 14-05-15, 13:22, Mason wrote:
> I didn't /literally/ take a stop-watch to verify it was EXACTLY
> 9 seconds, but I was staring at the prompt, and it /felt/ like
> 9 seconds. And the 54 second case felt like a minute.

:)

> I'm using a 27 MHz crystal as clocksource. This is independent
> of the CPU frequency. However, I'm using the ARM TWD as the
> system's clockevent source, and the TWD's clock is tied to
> the CPU clock (PERIPHCLK = CPUCLK / 2 on this SoC).

The only (very straight forward) problem is that we aren't propagating
the freq update to clockevents core and you need to debug a bit there.

Also I wanted to see the source of your print message:
[   19.650454] NEW RATE=9250000
[   19.653644] NEW RATE=9250000

What's this rate ? Old/new ? Because you are atleast printing the old
rate here, and the function by default gets the new rate.

> I'm wondering if there's another standard clockevent source
> I could try (it would be great if it supported high-resolution
> timers).

I hope you have some platform general-purpose-timers.

-- 
viresh

  reply	other threads:[~2015-05-14 11:54 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-12 14:32 schedule_timeout sleeps too long after dividing CPU frequency Mason
2015-05-12 14:46 ` Viresh Kumar
2015-05-12 15:14   ` Mason
2015-05-12 15:50     ` Russell King - ARM Linux
2015-05-12 16:14       ` Mason
2015-05-13 16:51       ` Mason
2015-05-14  2:13         ` Viresh Kumar
2015-05-14 11:22           ` Mason
2015-05-14 11:54             ` Viresh Kumar [this message]
2015-05-14 13:06               ` Mason
2015-05-14 13:53                 ` Russell King - ARM Linux
2015-05-14 14:51                   ` Mason
2015-05-14 13:59                 ` Viresh Kumar
2015-05-14 14:38                   ` Viresh Kumar
2015-05-14 14:42                   ` Russell King - ARM Linux
2015-05-15  9:29                     ` Mason
2015-05-15  9:51                       ` Russell King - ARM Linux
2015-05-15 10:01                         ` Viresh Kumar
2015-05-15 10:36                         ` Mason
2015-05-15 11:58                           ` Russell King - ARM Linux
2015-05-15 12:45                             ` Mason
2015-05-15 13:15                               ` Russell King - ARM Linux
2015-05-15 13:58                                 ` Mason
2015-05-15 18:35                                   ` Mason
2015-05-18 11:24                                     ` Mason
2015-05-18 11:54                                       ` Russell King - ARM Linux
2015-05-20 16:21                                         ` Mason
2015-05-20 18:50                                           ` Arnd Bergmann
2015-05-20 19:34                                             ` Mason
2015-05-20 20:14                                               ` Russell King - ARM Linux
2015-05-20 20:41                                                 ` Mason
2015-05-20 20:52                                                   ` Arnd Bergmann
2015-05-20 21:56                                                     ` Mason
2015-05-20 22:18                                                       ` Arnd Bergmann
2015-05-21 12:35                                                         ` Mason
2015-05-20 23:14                                                       ` Russell King - ARM Linux
2015-05-21  9:56                                                         ` Mason
2015-05-21 10:20                                                           ` Russell King - ARM Linux
2015-05-14 14:48                   ` Mason
2015-05-15  4:16                     ` Viresh Kumar
2015-05-15  5:07                       ` Viresh Kumar
2015-05-15  9:00                       ` Russell King - ARM Linux
2015-05-15  9:21                       ` Mason
2015-05-15 10:11                       ` Mason
2015-05-12 15:23 ` Russell King - ARM Linux
2015-05-12 16:03   ` Mason

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