Re: Compiling 2.2.19 with -O3 flag

Alan Cox (alan@lxorguk.ukuu.org.uk)
Fri, 24 May 2002 15:42:26 +0100 (BST)

> I would like to ask when compiling with -O3 flag on a
> kernel such as 2.2.19, what harm / side effect will I
> feel later on if any? will i loose speed in other area's?

Bench it and see. From my own experience -O3 made the kernel a lot larger
and reduced overall performance - in part because the kernel already
explicitly figures out what it wants inlined.

Interestingly enough -Os outperformed -O2
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