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Message-ID: <4AF9A77E.6020908@caviumnetworks.com>
Date:	Tue, 10 Nov 2009 09:48:46 -0800
From:	David Daney <ddaney@caviumnetworks.com>
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To:	Wu Zhangjin <wuzhangjin@gmail.com>
CC:	linux-mips@linux-mips.org, linux-kernel@vger.kernel.org,
	zhangfx@lemote.com, zhouqg@gmail.com,
	Ralf Baechle <ralf@linux-mips.org>, rostedt@goodmis.org,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Ingo Molnar <mingo@elte.hu>,
	Nicholas Mc Guire <der.herr@hofr.at>,
	Richard Sandiford <rdsandiford@googlemail.com>,
	Patrik Kluba <kpajko79@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Michal Simek <monstr@monstr.eu>
Subject: Re: [PATCH v7 03/17] tracing: add MIPS specific trace_clock_local()
References: <9dc81a7a9e5a292cccdf465c533a2b08d19d6021.1257779502.git.wuzhangjin@gmail.com> <b99c08397d9ff92ac5a72bda9131df41b702fc71.1257779502.git.wuzhangjin@gmail.com> <8f579e2cece16cd22358a4ec143ef6a8c462639b.1257779502.git.wuzhangjin@gmail.com>
In-Reply-To: <8f579e2cece16cd22358a4ec143ef6a8c462639b.1257779502.git.wuzhangjin@gmail.com>
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Wu Zhangjin wrote:
[...]
> + * trace_clock_local(): the simplest and least coherent tracing clock.
> + *
> + * Useful for tracing that does not cross to other CPUs nor
> + * does it go through idle events.
> + */
> +u64 trace_clock_local(void)
> +{
> +	unsigned long flags;
> +	u64 clock;
> +
> +	raw_local_irq_save(flags);
> +
> +	clock = mips_timecounter_read();
> +
> +	raw_local_irq_restore(flags);
> +
> +	return clock;
> +}

Why disable interrupts?

Also you call the new function mips_timecounter_read().  Since 
sched_clock() is a weak function, you can override the definition with a 
more accurate version when possible.  Then you could just directly call 
it here, instead of adding the new mips_timecounter_read() that the 
'[PATCH v7 02/17] tracing: add mips_timecounter_read() for MIPS' adds.

David Daney