Hi Saugata,
u caught me. Atcually I mistook && for & :-)
Things look fine to me now.
Thanks.
Sumit.
On Wed, 22 Sep 2004 Saugata.Chatterjee@xxxxxxxxxxxxxxxx wrote :
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>After the first loop, if loops_per_jiffy is equal to x, then we know that
>the 'exact' value of it is actually between x and x/2. The second loop
>helps us narrow this down to the actual value (upto LPS_PREC precision
>bits) by starting loops_per_jiffy (and loopbits) at x/2 and adding x/4,
>x/8, x/16 and so on if a clock tick passes inside __delay when loopbits is
>at that particular value.
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> So I don't understand your question. Why will the second loop always
>fail? It won't.
>
> Maybe rereading the code will help :) And making sure that you are not
>confusing & with && or > with >>.
>
> If you still have doubts, send me an offlist mail and I can explain in
>greater detail.
>
>Regards,
>-Saugata Chatterjee.
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> "matrix reloaded"
> <matrix_reloaded18@redi To: kernelnewbies@xxxxxxxxxxxx
> ffmail.com> cc:
> Sent by: Subject: BogoMips confusion ?
> kernelnewbies-bounce@nl
> .linux.org
>
>
> 09/22/2004 07:17 AM
> Please respond to
> "matrix reloaded"
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>Hi,
> I am going through the code for calculating BogoMips on i386 platform.
>The
>code is there in "init/main.c". The main function for this is
>"calibrate_delay()". If you
>go through the code for calibrate_delay(), you can see that it sets
>loops_per_jiffies
>to 4096 at the starting of the first while loop. Based on the processor's
>speed, it
>goes on incrementing [making it double] its value by (loops_per_delay <<=
>1)... It
>comes out of the first while loop, once there is a difference between new
>jiffies and
>old jiffies. Now the problem starts after this...
>
>At the second while loop you can see that
>
>while ( lps_precision-- && (loopbit >>= 1) ) {...
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>the aboce condition will fail always, as the starting value for
>lps_precision is
>LPS_PREC which has been defined to 8.
>Why is this loop there, if it will never execute ? because loopbit value
>will never be
>< 4096...
>
>TIA.
>
>Sumit Sharma
>IBM, Bangalore.
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>(Embedded image moved to file: pic20649.gif)
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