linux-kernel - Re: [PATCH] fix granularity of task

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Message-ID: <4AFB77C2.8080705@jp.fujitsu.com>
Date:	Thu, 12 Nov 2009 11:49:38 +0900
From:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
To:	Stanislaw Gruszka <sgruszka@...hat.com>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Spencer Candland <spencer@...ehost.com>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH] fix granularity of task_u/stime()

Hidetoshi Seto wrote:
> Stanislaw Gruszka wrote:
>> On Tue, Nov 10, 2009 at 02:47:34PM +0900, Hidetoshi Seto wrote:
>>> Remove casting to clock_t from task_u/stime(), and keep granularity of
>>> cputime_t over the calculation.
>>>
>>> Signed-off-by: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
>>> ---
>>>  kernel/sched.c |   21 ++++++++++++---------
>>>  1 files changed, 12 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/kernel/sched.c b/kernel/sched.c
>>> index 28dd4f4..1632e82 100644
>>> --- a/kernel/sched.c
>>> +++ b/kernel/sched.c
>>> @@ -5171,41 +5171,44 @@ cputime_t task_stime(struct task_struct *p)
>>>  	return p->stime;
>>>  }
>>>  #else
>>> +
>>> +#ifndef nsecs_to_cputime
>>> +# define nsecs_to_cputime(__nsecs) msecs_to_cputime((__nsecs) / NSEC_PER_MSEC)
>>> +#endif
>>> +
>> I would like to test, but unfortunately with the patch kernel not build
>> on my system:
>>
>> kernel/built-in.o: In function `task_utime':
>> /usr/src/rhel5/linux-2.6/kernel/sched.c:5187: undefined reference to
>> `__udivdi3'
>> kernel/built-in.o: In function `task_stime':
>> /usr/src/rhel5/linux-2.6/kernel/sched.c:5208: undefined reference to
>> `__udivdi3'
>> make: *** [.tmp_vmlinux1] Error 1
> 
> Wow, what arch?
> Could you provide your .config?

Oh, I found I can hit this error on x86_32 (but not on x86_64).
Maybe something on dividing u64...

I'll try to find fix/workaround for this, but would appreciate if someone
could tell me what is happening here.


Thanks,
H.Seto

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