Tickless Hz/hrtimers/etc. on PowerPC

Sergei Shtylyov sshtylyov at ru.mvista.com
Fri Jul 13 00:11:38 EST 2007


Hello.

Domen Puncer wrote:

>>Does anyone have the definitive patchset to enable the tickless hz,
>>some kind of hrtimer and the other related improvements in the
>>PowerPC tree?

> I use attached patches for tickless.
> Order in which they're applied:

> PowerPC_GENERIC_CLOCKEVENTS.patch

    That's my patch which used to have both description and signoff that I'm 
not seeing in the attached version...

> PowerPC_GENERIC_TIME.linux-2.6.18-rc6_timeofday-arch-ppc_C6.patch

    This one should come first of all, I'd say...
    Note that it breaks TOD vsyscalls, so you need my patch that removes 
support for those for the time being (i.e. until Tony hopefully fixes this 
:-).  Also, there was a patch implementing read_persistent_clock() and getting 
rid of the code setting xtime in time_init().  Attaching them both...

> PowerPC_enable_HRT_and_dynticks_support.patch

    Again looks like my patch with description/signoff missing for whatever
reason...

> PowerPC_no_hz_fix.patch

    This has nothing to do with CONFIG_NO_HZ per se -- it fixes the 
compilation error introduced by John's patch.

> tickless-enable.patch

    That one doesn't look quite right...

> HTH

> 	Domen

[...]

> ------------------------------------------------------------------------
> 
> This is needed for hrtimer_switch_to_hres() to get called.
> hrtimer_run_queues()
> |-tick_check_oneshot_change()
> | \-timekeeping_is_continuous()
> |   \- flags check
> \-hrtimer_switch_to_hres()

> Signed-off-by: Domen Puncer <domen.puncer at telargo.com>

> Index: work-powerpc.git/arch/powerpc/kernel/time.c
> ===================================================================
> --- work-powerpc.git.orig/arch/powerpc/kernel/time.c
> +++ work-powerpc.git/arch/powerpc/kernel/time.c
> @@ -1039,6 +1039,7 @@ struct clocksource clocksource_timebase 
>  	.mask = (cycle_t)-1,
>  	.mult = 0,
>  	.shift = 22,
> +	.flags = CLOCK_SOURCE_VALID_FOR_HRES,
>  };

     Hm, has the flag name changed from CLOCK_SOURCE_IS_CONTINOUS? I'm seeign
both there flags, therefore it must be CLOCK_SOURCE_IS_CONTINOUS, not
CLOCK_SOURCE_VALID_FOR_HRES.

WBR, Sergei

PS: All attached patches are against 2.6.21-rt2 -- fitting them into the 
current (or whatever) version of the kernel is left as an excercise to the 
readers. ;-)

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