Profiling Optimised Code
Simon Peyton-Jones
simonpj@microsoft.com
Tue, 2 Sep 2003 16:56:05 +0100
Did anyone reply to this? It's an open bug
=09
http://sourceforge.net/tracker/index.php?func=3Ddetail&aid=3D710864&group=
_id
=3D8032&atid=3D108032
but we don't have a small example that demonstrates it. =20
Can you provide one? Or can Amanda?
Simon
| -----Original Message-----
| From: glasgow-haskell-users-admin@haskell.org
[mailto:glasgow-haskell-users-admin@haskell.org]
| On Behalf Of Ashley Yakeley
| Sent: 03 August 2003 09:32
| To: glasgow-haskell-users@haskell.org
| Subject: Profiling Optimised Code
|=20
| The profiling report from my program compiled with GHC 6.0 with -O
| -fvia-C on Mac OS X isn't making a lot of sense. The line with the
most
| time, 30.1%, has an entry count of zero, as do most of them:
|=20
| exprLetMap
| Org.Org.Semantic.HScheme.Interpret.LambdaExpression 1939 0
| 0.3 0.0 30.3 0.0
| liftF2 Org.Org.Semantic.HBase.Category.Functor
| 1940 0 0.0 0.0 30.1 0.0
| liftF1 Org.Org.Semantic.HBase.Category.Functor
| 1941 0 30.1 0.0 30.1 0.0
|=20
| It's also a fairly unlikely candidate for time consumption. liftF1 is
| defined as simply equal to fmap, which presumably doesn't have a
| cost-centre because it's defined in the standard libraries. But the
| instance of fmap that it calls is fairly trivial.
|=20
| Am I misinterpreting the report, or would I be better off profiling a
| unoptimised program to see where the slow bits are in that? I have
| successfully improved code based on reports from unoptimised programs
| from GHC 5.*, since those reports made much more sense.
|=20
| --
| Ashley Yakeley, Seattle WA
|=20
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