Messages in this thread | | | Subject | Re: Compiling 2.2.19 with -O3 flag | From | Robert Love <> | Date | 24 May 2002 08:19:03 -0700 |
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On Fri, 2002-05-24 at 07:42, Alan Cox wrote:
> 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
Heh, now that is interesting.
Or maybe not - not too long ago I did some tests of the various optimization options in gcc 2.96 or so and found that -O2 generates smaller code in most cases than -Os. -Os also did not perform as good, but I was just testing a few bits of code - nothing as versatile as the kernel.
The end result was I recommend -O2 for both performance and size. Maybe I should retest against the kernel...
Robert Love
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