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To: Zan Lynx <zlynx@acm.org>
Cc: Ingo Molnar <mingo@elte.hu>, Davide Libenzi <davidel@xmailserver.org>,
       Jeff Garzik <jgarzik@pobox.com>, Greg KH <greg@kroah.com>,
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       Netdev <netdev@oss.sgi.com>
Subject: Re: MSEC_TO_JIFFIES is messed up...
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From: Roland Dreier <roland@topspin.com>
Date: 12 May 2004 15:05:07 -0700
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  > Being curious, I tried that and got the same results.  But this:
  > 
  > int f(unsigned int x)
  > {
  >         return x * (1000 / 1000);
  > }
  > 
  > creates this:
  > f:
  >         pushl   %ebp
  >         movl    %esp, %ebp
  >         movl    8(%ebp), %eax
  >         leave
  >         ret

Of course the compiler can optimize (1000 / 1000) into 1 at compile
time.  However, the original code was doing something like

	x * HZ / 1000

if you change that to

	x * (HZ / 1000)

then obviously that breaks if HZ is not a multiple of 1000.

 - Roland