Subject: Re: [question] I doublt on timer interrput.
From: Robert Love <rml@novell.com>
To: liyu <liyu@ccoss.com.cn>
Cc: LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <436EEEA4.1020703@ccoss.com.cn>
References: <436EEEA4.1020703@ccoss.com.cn>
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Date: Mon, 07 Nov 2005 11:16:13 -0500
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On Mon, 2005-11-07 at 14:05 +0800, liyu wrote:
> Hi, all:
> 
>     I have one question about timer interrupt (i386 architecture).
> 
>     As we known, the timer emit HZ times interrputs per second,
> and in i386. The interrupt handler will call scheduler_tick()
> each time (on i386 at least, both enable or disable APIC).
> 
>     On my Celeron machine(IOW, only one CPU, not SMP/SMT), I defined
> a global int variable 'tick_count' in kernel/sched.c, and add one line
> of code like follow in scheduler_tick():
> 
>     ++tick_count;
> 
>     but I found it is not same with content of the /proc/interrupts,
> and the differennt between them is not little.
>    
>     I can not understand why that is.
>    
>     Any useful idea.

scheduler_tick() is not the timer interrupt.

You want to hook into do_timer() or similar.

	Robert Love


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