Messages in this thread | | | Date | Mon, 15 Sep 2003 08:15:25 -0700 | From | "Martin J. Bligh" <> | Subject | Re: [2.6 patch] add a config option for -Os compilation |
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--Alan Cox <alan@lxorguk.ukuu.org.uk> wrote (on Sunday, September 14, 2003 15:57:49 +0100):
> On Sul, 2003-09-14 at 14:53, Wade wrote: >> Adrian Bunk wrote: >> > The patch below adds a config option OPTIMIZE_FOR_SIZE for telling gcc >> > to use -Os instead of -O2. Besides this, it removes constructs on >> > architectures that had a -Os hardcoded in their Makefiles. >> >> Someone told me that -Os is actually faster than -O2 for Athlons, is >> that true? > > On gcc 2.95 -Os was faster for most stuff. I would intuitively expect > the best result to be a mix varied by function but I don't think gcc has > the support to do that. > > I've also not benched gcc 3.2 -Os v -O2 at real workloads - thats a > nice little project for someone.
I think it depends heavily on the chip - I tried 2.95 and 3.3. For me, -Os was slower for both, but I have a 2MB L2 cache. If you have a 128K celeron or something, I'm sure it'd be faster.
M.
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