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    SubjectRe: [Lse-tech] 7.52 second kernel compile
    Date
    On Sat, 16 Mar 2002 09:37:00 -0800, 
    "Martin J. Bligh" <Martin.Bligh@us.ibm.com> wrote:
    >Are you still doing something like this?
    ># MAKE="make -j14" /usr/bin/time make -j14 bzImage
    >
    >I tried setting the MAKE variable as well as doing the -j,
    >but it actually made kernel compile time slower - what difference
    >does it make on your machine? Can somebody clarify what this
    >actually does, as opposed to the -j on the command line?

    It depends on which version of make you are using. make 3.78 onwards
    has a built in job scheduler which shares the value of -j across its
    children, yea unto the nth generation. Earlier versions of make did a
    simplistic 'run -j copies of make at the top level' and did not
    propagate -j to the lower levels.

    With the recursive makefiles and make < 3.78 you need MAKE="make -j" to
    get a decent speedup because of the lack of choices at the top level
    Makefile. With make >= 3.79 you do not need MAKE="make -j14", it can
    interfere with make's own scheduler. See also make -l LOAD.

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