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TODO (was Re: [PATCH] Re: change #9754: 5 x slowdown for perl -d)

From:
Nicholas Clark
Date:
February 1, 2003 03:40
Subject:
TODO (was Re: [PATCH] Re: change #9754: 5 x slowdown for perl -d)
Message ID:
20030201113649.GC279@Bagpuss.unfortu.net
On Mon, Jan 27, 2003 at 01:08:07AM +0200, Jarkko Hietaniemi wrote:

> > So there's nothing big to come out :-(
> > Any speed improvements have to be found from new ideas?
> 
> Finding out hot spots, writing fast paths for them, inlining them.
> Oh, sorry, you said *new* ideas...

Is there a list of known hot spots?
By "known", I mean known down to the accuracy to paths through particular
functions that are slow, with benchmarking test cases?

So "regexp engine is too slow" is known but not helpful,
"regexp engine is too slow on /(?:(?:.*)*)/" is still not helpful
but "regexp engine is too slow on /(?:(?:.*)*)/" because of path through
function blah would be.

There's the old hairy chestnut of benchmarks

1: what do we use to pinpoint things that are slow
and
2: what do we use to verify that the rest of perl on "average" doesn't slow
   down as a result of accelerating a particular hot path

Does RT (or anything else) provide an easy facility to maintain such a list?
Or should we assimilate one by patches into a core file? [this doesn't feel as
good, mainly because the current perl TODO list is monolithic, not very
prioritised, not allocated, hard to change and full of cruft]

Nicholas Clark



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