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* pow calculation in kernel
@ 2014-06-20  1:55 =?gb18030?B?1cXqzw==?=
  2014-06-20  2:40 ` John de la Garza
  0 siblings, 1 reply; 2+ messages in thread
From: =?gb18030?B?1cXqzw==?= @ 2014-06-20  1:55 UTC (permalink / raw)
  To: kernelnewbies

Hi:
  
 I am doing a research on D2TCP(http://dl.acm.org/citation.cfm?id=2342388), I just want to implement it into the linux kernel. When calculating the penalty function, it is p = a^d, where 0< a < 1 and  0< d < 1. Since the kernel only offers integer,   so in my code, so I let a multiply 2^10. But I have no idea of calculating a^d when 0< d < 1. May be I want a  approximate algorithm or other methods. Can you help me ?
 thanks~

  
  ------------------
  
???
 
??
 
 
 
---------- 
 
HanZhang
 
School of Computer Science
Tsinghua University, Beijing, 100084, P.R.CHINA
 
Mobile:  +86 156-526-59782
E-mail:   zhanghan@csnet1.cs.tsinghua.edu.cn
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* pow calculation in kernel
  2014-06-20  1:55 pow calculation in kernel =?gb18030?B?1cXqzw==?=
@ 2014-06-20  2:40 ` John de la Garza
  0 siblings, 0 replies; 2+ messages in thread
From: John de la Garza @ 2014-06-20  2:40 UTC (permalink / raw)
  To: kernelnewbies

On Fri, Jun 20, 2014 at 09:55:02AM +0800, ?? wrote:
> Hi:
>   
>  I am doing a research on D2TCP(http://dl.acm.org/citation.cfm?id=2342388), I just want to implement it into the linux kernel. When calculating the penalty function, it is p = a^d, where 0< a < 1 and  0< d < 1. Since the kernel only offers integer,   so in my code, so I let a multiply 2^10. But I have no idea of calculating a^d when 0< d < 1. May be I want a  approximate algorithm or other methods. Can you help me ?
>  thanks~
> 

Could you achieve this using fixed point math?

you can see an example in include/linux/sched.h
(search for CALC_LOAD)

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