Hello all,

A friend and I are trying to benchmark some network server code which
runs fine on my OSX laptop (~7500 req/s) but which is >10x slower on a
much faster 8-core Xeon Linux box.

The profiling run on Linux looks like this:

individual inherited
COST CENTRE MODULE no. entries %time %alloc %time %alloc

MAIN MAIN 1 0 95.7 0.2 100.0 100.0
...

How should we interpret this result? MAIN doesn't seem to correspond to
any user code so we're wondering where the time is going.

G.
--
Gregory Collins <greg@gregorycollins.net>
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Am Montag 08 Februar 2010 17:04:44 schrieb Gregory Collins:
> Hello all,
>
> A friend and I are trying to benchmark some network server code which
> runs fine on my OSX laptop (~7500 req/s) but which is >10x slower on a
> much faster 8-core Xeon Linux box.
>
> The profiling run on Linux looks like this:
>
> individual inherited
> COST CENTRE MODULE no. entries %time %alloc %time %alloc
>
> MAIN MAIN 1 0 95.7 0.2 100.0 100.0
> ...
>
> How should we interpret this result? MAIN doesn't seem to correspond to
> any user code so we're wondering where the time is going.

Insert lots of {-# SCC "foo" #-} pragmas (you did pass -auto-all on the
command line when compiling?). You can't interpret a profile where almost
everything is attributed to MAIN or main.

>
> G.

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Am Montag 08 Februar 2010 18:15:30 schrieb Gregory Collins:
>
> I'm just curious as to what the meaning of the MAIN cost centre is -- is
> it just a catch-all bucket? Are we measuring time spent in the runtime
> system?
>
> G

MAIN is always the root of the call-tree, so I think it's the cost-centre
which subsumes all. That its inherited cost is 100% is natural, thus. But
usually, its individual cost is 0%, so there's something strange going on.
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