Re: [PATCH 2/5] Add nsecs_to_cputime64 interface for asm-generic-v2

[Martin Schwidefsky]

On Wed, 22 Dec 2010 06:23:55 -0800
Venkatesh Pallipadi <venki@xxxxxxxxxx> wrote:

> On Wed, Dec 22, 2010 at 12:30 AM, Martin Schwidefsky
> <schwidefsky@xxxxxxxxxx> wrote:
> > On Tue, 21 Dec 2010 17:09:01 -0800
> > Venkatesh Pallipadi <venki@xxxxxxxxxx> wrote:
> >
> >> Add nsecs_to_cputime64 interface. This is used in following patches that
> >> updates cpu irq stat based on ns granularity info in IRQ_TIME_ACCOUNTING.
> >>
> >> Tested-by: Shaun Ruffell <sruffell@xxxxxxxxxx>
> >> Signed-off-by: Venkatesh Pallipadi <venki@xxxxxxxxxx>
> >> ---
> >> Âinclude/asm-generic/cputime.h | Â Â3 +++
> >> Âinclude/linux/jiffies.h    |  Â1 +
> >> Âkernel/time.c         |  23 +++++++++++++++++++++--
> >> Â3 files changed, 25 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/include/asm-generic/cputime.h b/include/asm-generic/cputime.h
> >> index 2bcc5c7..61e03dd 100644
> >> --- a/include/asm-generic/cputime.h
> >> +++ b/include/asm-generic/cputime.h
> >> @@ -30,6 +30,9 @@ typedef u64 cputime64_t;
> >> Â#define cputime64_to_jiffies64(__ct) (__ct)
> >> Â#define jiffies64_to_cputime64(__jif) Â Â Â Â(__jif)
> >> Â#define cputime_to_cputime64(__ct) Â ((u64) __ct)
> >> +#define cputime64_gt(__a, __b) Â Â Â Â Â Â Â ((__a) > Â(__b))
> >> +
> >> +#define nsecs_to_cputime64(__ct) Â Â nsecs_to_jiffies64(__ct)
> >>
> >>
> >> Â/*
> >
> > If you define a new cputime primitive it is not enough to add it to the
> > generic cputime header. You have to add it to the arch-specific cputime
> > header for ia64, powerpc and s390 as well. Otherwise the build will
> > break with CONFIG_VIRT_CPU_ACCOUNTING=y on these architectures once the
> > new primitive is used.
> >
> 
> But, those archs have arch specific cputime as well and so need a
> different macro for nsecs_to_cputime64, instead of nsec_to_jiffies64.
> Right? As of now this new primitive should not be used in those archs.
> I guess this is something needed when using the primitive in future?

Yes on both parts of the question. You need an independent
implementation of the nsecs_to_cputime64 primitive for the architectures
that have their own definition of cputime and this definition will be
needed when the primitive is used is the future.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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