[EMAIL PROTECTED] wrote on Wed, 22 Feb 2006 10:10 -0500:
> It appears that compile errors I'm running into with PVFS2 and
> Silverstorm/Mellanox infiniband are definitions in the ib code that
> duplicate definitions in kernel headers. Specifically:
>
> #define likely(x) __builtin_expect(!!(x), 1)
> #define unlikely(x) __builtin_expect(!!(x), 0)
>
> Do you think it may be appropriate to call these
>
> PVFS2_likely and PVFS2_unlikely to avoid name collisions with kernel
> #defines? We could also test for their existince, though then we
> couldn't be certain what the macro did exactly. Any strong opinions?
None of the IB code interacts with the kernel code, but I guess the
Silverstorm userspace IB headers must either pull in kernel headers
(blecch) or define likely() for their own purposes.
I agree renaming those functions in the pvfs2 IB code is the way to
go. Perhaps a naming guru could suggest if we should change them
to
PVFS2_likely
PVFS2_unlikely
as you suggest or would prefer
PINT_likely
PINT_unlikely
or even something to keep it BMI-specific?
It's just an optimization to help the compiler with branch
prediction. I try only to use it for assert-like things where the
likelihood of the outcome is really obvious.
-- Pete
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