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    SubjectRe: [PATCH 18 of 20] ipath - kbuild infrastructure
    On Mon, Mar 13, 2006 at 11:24:28AM -0800, Bryan O'Sullivan wrote:
    > On Mon, 2006-03-13 at 19:10 +0100, Adrian Bunk wrote:
    >
    > > I'm still a bit surprised, since in the rest of the kernel we are even
    > > going from -O2 to -Os for getting better performance.
    > >
    > > Robert said he wanted to post some numbers showing that -O3 is
    > > measurably better for you [1], but I haven't seen them.
    >
    > I just ran some numbers. At large packet sizes, it doesn't matter what
    > options we use, because we spend all of our time in __iowrite_copy32,
    > which uses the string copy instructions.
    >
    > For small packets, my quick tests indicate that -Os gives about 5%
    > *better* performance than -O3 (using gcc 4 on FC4). This is in line
    > with what people have been finding in the kernel in general recently.
    >
    > So if I change that CFLAGS line from -O3 to -Os, are we in OK
    > shape? :-)
    Use the kernel settings. We cannot have this modified by each and every
    driver.

    Sam
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