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Re: Tickless/dyntick kernel, highres timer and general time crapectomy

To: "Ralf Baechle" <ralf@linux-mips.org>
Subject: Re: Tickless/dyntick kernel, highres timer and general time crapectomy
From: "Franck Bui-Huu" <vagabon.xyz@gmail.com>
Date: Thu, 7 Jun 2007 09:59:53 +0200
Cc: linux-mips@linux-mips.org
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Hi Ralf,

Ralf Baechle wrote:
Time to send bring this to a larger audience.

I'm working on getting dyntick and highres timer support working for MIPS.
This unavoidably implies dumping most of the MIPS-private time
infrastructure we've piled up over the past decade.  Which really is a
major crapectomy.  A first cut of the patches which are tested to
run

That's definitely true. I wrote my own version of clockevent support
yesterday based on your patchset "dyntick-quilt" and I end up rewrite
the whole time.c. The biggest part of the job would be to split this
into several patches to ease the review but I doubt it worth it since
we rewrite it almost from scratch.

Another issue I have is to implement clockevent set_mode() method. You
left it empty but I think we need at least to shut down the timer
interrupt when setting the clock event device. Strangely I haven't
found a "generic" way to stop them through cp0. Have I missed
something ? If not, that would mean that either we need a new hook to
achieve that or we find a way/hack to do that in a mips generic
way. Advice on this point would be appreciated.

well on uniprocessor and VSMP Malta kernels is at:


  ftp://ftp.linux-mips.org/pub/linux/mips/people/ralf/dyntick-quilt

It will also likely work on various other simple systems.  A more recent
version of these patches which I haven't yet gotten around to test on
silicon is available at:

  ftp://ftp.linux-mips.org/pub/linux/mips/people/ralf/linux-time.patches


BTW any idea when "time-ntp-make-cmos-update-generic.patch" is going
to be merged into mainline ? Note: I think there's a bug in
notify_cmos_timer(). The following test should be negated, shouldn't
it ?

+       if (no_sync_cmos_clock)
+               mod_timer(&sync_cmos_timer, jiffies + 1);

The other patch named "time-move-to_tm-to-lib.patch" create a new file
in arch/mips/lib directory. This new file is called
"to_tm.c". Shouldn't we call it something less specific like "time.c" ?

--
              Franck

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