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Re: [PATCH] change CLOCKS_PER_SEC to match POSIX:XSI


Joel Sherrill wrote:

Corinna Vinschen wrote:
On Oct 6 13:19, Bob Wilson wrote:

The XSI extension to POSIX requires that CLOCKS_PER_SEC be defined to one million. The current value in newlib, except for RTEMS and ARM, is 1000. Since this value seems pretty arbitrary, wouldn't it be better to go with the POSIX value? Here is a patch to change it.

2005-10-06 Bob Wilson <bob.wilson@acm.org>

* libc/include/time.h (CLOCKS_PER_SEC): Define to 1000000.


Careful, please. This could break newly compiled applications on systems using the CLOCKS_PER_SEC macro internally.

I always thought this was an arbitrary and useless macro.  On RTEMS
and many other systems, the clock tick quantum is configurable.

Why is 1000000 suddenly right?

I'm afraid I can't answer the "why" question. I stumbled upon this requirement a while back when I was trying to decide upon a less arbitrary value for this macro.


Judging from various mailing list archives, the change has been somewhat controversial, but it appears that several other prominent C libraries have adopted it.

The default value is easily overridden, so I'm not going to push very hard to get the default changed. I thought it was at least worth calling to your attention.

--Bob


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