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Subject: Re: [PATCH v5] MIPS: Add a high resolution sched_clock() via
 cnt32_to_63().
From:   Wu Zhangjin <wuzhangjin@gmail.com>
Reply-To: wuzhangjin@gmail.com
To:     Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc:     Ralf Baechle <ralf@linux-mips.org>, Ingo Molnar <mingo@elte.hu>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-mips@linux-mips.org, Michal Simek <monstr@monstr.eu>
In-Reply-To: <4B0EC5CB.5060701@ru.mvista.com>
References: <39b95d02b37cd75d275b231c31abb00aefda9078.1258972025.git.wuzhangjin@gmail.com>
         <4B0A8A0B.60405@ru.mvista.com>  <4B0EC5CB.5060701@ru.mvista.com>
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Organization: DSLab, Lanzhou University, China
Date:   Fri, 27 Nov 2009 09:07:15 +0800
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On Thu, 2009-11-26 at 21:15 +0300, Sergei Shtylyov wrote:
> Hello, I wrote:
> 
> >> From: Wu Zhangjin <wuzhangjin@gmail.com>
> 
> >> (This v5 revision incorporates with the feedbacks from Ingo.)
> 
> >> This patch adds a cnt32_to_63() and MIPS c0 count based sched_clock(),
> >> which provides high resolution. and also, one new kernel option
> >> (HR_SCHED_CLOCK) is added to enable/disable this sched_clock().
> 
> >> Without it, the Ftrace for MIPS will give useless timestamp information.
> 
> >> Because cnt32_to_63() needs to be called at least once per half period
> >> to work properly, Differ from the old version, this v2 revision set up a
> >> kernel timer to ensure the requirement of some MIPSs which have short c0
> >> count period.
> 
> >> Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
> 
> >> diff --git a/arch/mips/kernel/csrc-r4k-hres.c 
> >> b/arch/mips/kernel/csrc-r4k-hres.c
> >> new file mode 100644
> >> index 0000000..2fe8be7
> >> --- /dev/null
> >> +++ b/arch/mips/kernel/csrc-r4k-hres.c
> > 
> > 
> >    I don't think this is really good name for this file (one might think 
> > that this is another implementation of clocksource instead of some 
> > sched_clock() code tied to this particular clocksource), and I don't 
> 
>     Seriously, if this file have to live a life of its own, name it like 
> sched-r4k.c but not the way you named it -- this is not another clocksource 
> module...
> 
> WBR, Sergei

okay, later.

Thanks,
	Wu Zhangjin