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From: Marco Correia <mvc@netcabo.pt>
To: linux-kernel@vger.kernel.org
Subject: why is rdtsc reporting wrong cpu cycles?
Date: Sat, 3 Jan 2004 15:48:39 +0000	[thread overview]
Message-ID: <200401031548.40025.mvc@netcabo.pt> (raw)

Hi,

I'm using the following function for getting the number of CPU cycles elapsed 
since I rebooted:

/* Read Timer Stamp Counter */
unsigned long long int rdtsc(void)
{
   unsigned long long int x;

   __asm__ volatile(".byte 0x0f,0x31" : "=A" (x));
   return x;
}

The problem is that the value I get dividing by my processor frequency (my 
computer is a 650Mhz toshiba satellite pro 4340) is giving me about 1 hour 
and I'm using the computer for about 4 fours.

Am I forgetting something obvious? I already googled around but I came to the 
conclusion that only new P4 M processors are able to change speed. 

I'm sorry if this is not the place to ask.

Thanks
Marco

ps: Please CC me as I'm not subscribed

-- 
Marco Correia <mvc@netcabo.pt>


             reply	other threads:[~2004-01-03 15:48 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-01-03 15:48 Marco Correia [this message]
2004-01-03 16:55 ` Willy Tarreau

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