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    SubjectRe: [PATCH 18 of 20] ipath - kbuild infrastructure
    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? :-)

    > > +_ipath_idstr:="PathScale $(shell date +%F)"
    > > +EXTRA_CFLAGS += -DIPATH_IDSTR='$(_ipath_idstr)' -DIPATH_KERN_TYPE=0
    > >...
    > UTS_VERSION is already available and printed at the top of dmesg.
    > I don't see the point in printing it a second time.

    Good point. The idstr stuff is for our out-of-tree drivers.



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