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    SubjectRe: Specific support for Intel Atom architecture

    * Arjan van de Ven <arjan@infradead.org> wrote:

    > On Mon, 4 May 2009 15:14:57 +0200
    > Ingo Molnar <mingo@elte.hu> wrote:
    >
    > >
    > > * Tobias Doerffel <tobias.doerffel@gmail.com> wrote:
    > >
    > > > Am Sonntag, 3. Mai 2009 08:48:54 schrieb H. Peter Anvin:
    > > > > Willy Tarreau wrote:
    > > > > >> $(call cc-option,-march=atom,-march=i686)
    > > > > >
    > > > > > if it's an in-order architecture, wouldn't it be better to tune
    > > > > > for i386 or i486 instead ?
    > > > >
    > > > > Possibly. It would be worth measuring.
    > > >
    > > > How would one do that (never benchmarked kernel stuff before)?
    > >
    > > A standard method is to run lmbench and compare the results -
    > > lmbench has a built-in 'report comparison between two runs'
    > > feature.
    >
    > well... you're normally REALLY hard pressed to measure compiler
    > differences this way.....
    >
    > normally compiler options get benchmarked using speccpu and the
    > like....

    Well, if there's no measurable difference in lmbench at all then the
    options probably dont matter that much. If some workload is found
    where compiler options show a difference then that matters. Speccpu
    only matters if those compiler options also help the kernel, in a
    measurable way.

    Ingo


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