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From: David Brownell <david-b@pacbell.net>
To: "Bosko Radivojevic" <bosko.radivojevic@gmail.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
	linux-rt-users@vger.kernel.org, tglx@linutronix.de
Subject: Re: High resolution timers on AT91SAM926x
Date: Mon, 3 Mar 2008 17:29:18 -0800	[thread overview]
Message-ID: <200803031729.19264.david-b@pacbell.net> (raw)
In-Reply-To: <d6c8ef150803031342r567aab86x776dc2a8b73714b6@mail.gmail.com>

On Monday 03 March 2008, Bosko Radivojevic wrote:
> I had CONFIG_ATMEL_TCLIB enabled, but not TCB_CLKSRC and
> TCB_CLKSRC_BLOCK=0. With all those options, I finally have HRT
> functionality. But, strange thing is that jitter of my little example
> (get time, sleep 1ms, get time, show the difference) is around 250us.
> Maybe this is normal for this architecture?

I have no idea why that would be.  Maybe you can find out.  :)


> System is (as noted on rt.wik site) very slow with NO_HZ option enabled.

It doesn't exactly say *why* or compare to other arm926ejs
chips ... 

Could the 64-bit math (ktime stuff) be a factor there?  Your
board probably only runs at 95 (or-so) bogomips after all.

And is that just a NO_HZ issue, or generically an issue when
oneshot timer modes are in heavy use?

- Dave
 

  reply	other threads:[~2008-03-04  1:29 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-01 22:57 David Brownell
2008-03-03 10:26 ` Bosko Radivojevic
2008-03-03 18:39   ` David Brownell
2008-03-03 21:42     ` Bosko Radivojevic
2008-03-04  1:29       ` David Brownell [this message]
2008-03-04 20:22         ` Remy Bohmer
2008-03-04 20:55           ` Wolfgang Grandegger
     [not found] <d6c8ef150803010952g666118dfu7679593b3c92c8be@mail.gmail.com>
2008-03-01 17:59 ` Bosko Radivojevic

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