Re: BogoMips

Gordon Oliver (gordo@telsur.cl)
Wed, 24 Jun 1998 20:47:06 -0400

... Richard B. Johnson said ...
>This subject has come up so may times I thought I would take a look
>at it. Most know that BogoMips stands for "bogus" and is just a number
>obtained to calibrate short delay-loops. However, some are disturbed
>that recompiling the kernel will sometimes result in a different
>number. Even though this number means nothing to the end-user, to
>help prevent it from changing, I have provided this patch. It should
>patch cleanly on most recent kernels.
<snip>

you might try reading the archives as well. This has been hashed over
several times. Different processors have different effects, and in the
end it was determined that pretty much any choice of offset/alignment caused
"bogomips jitter" on some processor. E.g. a pentium will slow down if
the loop is in something like the first 16 bytes of a page (I don't
remember the exact number or if it was first/last...). Thats why
__delay got moved to a routine, instead of being inline.
-gordo

--
---------------------------------------------------------------
Gordon Oliver	(gordo@telsur.cl)	Independent Consultant
	... Available for consulting on Linux  ...






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