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Re: [PATCH v5] MIPS: Add a high resolution sched_clock() via cnt32_to_63

To: Wu Zhangjin <wuzhangjin@gmail.com>
Subject: Re: [PATCH v5] MIPS: Add a high resolution sched_clock() via cnt32_to_63().
From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 23 Nov 2009 11:36:50 +0100
Cc: Ralf Baechle <ralf@linux-mips.org>, Thomas Gleixner <tglx@linutronix.de>, linux-mips@linux-mips.org, Michal Simek <monstr@monstr.eu>, Sergei Shtylyov <sshtylyov@ru.mvista.com>
In-reply-to: <39b95d02b37cd75d275b231c31abb00aefda9078.1258972025.git.wuzhangjin@gmail.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <39b95d02b37cd75d275b231c31abb00aefda9078.1258972025.git.wuzhangjin@gmail.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.20 (2009-08-17)
* Wu Zhangjin <wuzhangjin@gmail.com> 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>
> ---
>  arch/mips/Kconfig                |   18 ++++++++++++
>  arch/mips/include/asm/time.h     |   15 ++++++++++
>  arch/mips/kernel/Makefile        |    1 +
>  arch/mips/kernel/csrc-r4k-hres.c |   54 
> ++++++++++++++++++++++++++++++++++++++
>  arch/mips/kernel/csrc-r4k.c      |    2 +
>  5 files changed, 90 insertions(+), 0 deletions(-)
>  create mode 100644 arch/mips/kernel/csrc-r4k-hres.c

Looks good!

Reviewed-by: Ingo Molnar <mingo@elte.hu>

Thanks,

        Ingo


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