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Re: commit: ldap/servers/slapd connection.c daemon.c proto-slap.h syncrepl.c
Howard Chu writes:
> The -O2 build is faster from about 4 to 24 client threads. From 28 on
> up, the nonoptimized code is faster at every load level. I was
> originally using gcc 4.1.2 but I'm seeing the same result now using
> gcc 4.2.2. Also, slapd is only configured with 8 worker threads in all
> of these tests. Strange that whatever optimizations the compiler has
> generated speeds things up for lighter load, but works against it
> under heavier load.
Not really. Lots of possible optimizations are trade-offs between
unguessable guesstimates - cache usage, branch prediction, whatever.
Maybe some small piece of code got unluckily optimized and dominates
the rest under heavy load. With a bit of luck, the difference between
light and heavy runs will stand out with some sort of profiling (gprof,
cachegrind, helgrind, whatever).