On Thu, Mar 18 2010, David Andersen wrote:
> Hi, fio hackers:
>
> Version 285d451f5c3e034463ea49a5ba99e8e0eb1b83a2
> (snapshot from yesterday)
>
> Tiny performance tweak with -DFIO_INC_DEBUG enabled but no debug flags specified (the default if building from source): the dprint macro calls getpid() before checking to see whether or not it's going to actually do anything. This causes a bit of a slowdown if you've built with debugging but aren't using it. The fix is to simply swap them:
>
> debug.h:
>
> #define dprint(type, str, args...) \
> do { \
> assert(type < FD_DEBUG_MAX); \
> if ((((1 << type)) & fio_debug) == 0) \
> break; \
> pid_t pid = getpid(); \
>
> I wasn't sure what the style guidelines were for non-initial declaration & assignment, though...
>
> Reproducing: run fio under 'perf'; observe 1.x% of time taken by getpid(). :)
Thanks, I'll commit a fix for that.
--
Jens Axboe
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