From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Subject: Re: linux-next: tip tree build warnings
Date: Mon, 7 Sep 2009 10:59:28 +0200 [thread overview]
Message-ID: <20090907105928.2646cb11@skybase> (raw)
In-Reply-To: <20090903121326.GA4724@osiris.boeblingen.de.ibm.com>
On Thu, 3 Sep 2009 14:13:26 +0200
Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
> On Thu, Sep 03, 2009 at 10:38:44AM +0200, Ingo Molnar wrote:
> > * Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> > > cputime_t is variously "u64", "unsigned long long" and "unsigned
> > > long" on different architectures.
> >
> > Should be unsigned long i think. Most architectures use it as
> > unsigned long via include/asm-generic/cputime.h, except these three:
> >
> > arch/ia64/include/asm/cputime.h:typedef u64 cputime_t;
> > arch/powerpc/include/asm/cputime.h:typedef u64 cputime_t;
> > arch/s390/include/asm/cputime.h:typedef unsigned long long cputime_t;
> >
> > Or we could eliminate the type altogether as well and standardize on
> > u64. Thomas?
>
> s390 uses 64 bit cputime_t because we want the high resolution also in
> 32 bit kernels. So standardizing on u64 would be the preferred solution
> for us.
The cputime_t type serves/served two purposes: 1) make it clear that
this is NOT a jiffie value, it is an architecture defined type with
architecture dependent semantic, 2) by redefining cputime_t to a
structure with a single embedded unsigned long I have been able to
identify all places in the kernel that do not use the proper cputime
functions. I'm not sure if we need 2) anymore.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
prev parent reply other threads:[~2009-09-07 8:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-03 8:25 linux-next: tip tree build warnings Stephen Rothwell
2009-09-03 8:38 ` Ingo Molnar
2009-09-03 12:13 ` Heiko Carstens
2009-09-03 12:24 ` Heiko Carstens
2009-09-07 8:59 ` Martin Schwidefsky [this message]
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