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Re: [Caml-list] ocaml-3.05: a performance experience
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Date: -- (:)
From: Damien Doligez <damien.doligez@i...>
Subject: Re: [Caml-list] ocaml-3.05: a performance experience
>From: "Alexander V. Voinov" <avv@quasar.ipa.nw.ru>

>Compiled with ocaml-3.04 it took 1h40m+-5m of 'user' process time and
>occupied about 340M in RAM. With 3.05 it took 2h40m+-5m and occupied
>250M. 

>Is this the consequence of the new GC strategy? Actually I'd tolerate
>large footprint for the sake of more speed.

Not really.  When debugging the problem of the compactor that would
not trigger, I stumbled on a bug in the way the GC determines its
speed (relative to the program).  In 3.04, when you ask for an
overhead of 42% (the default), the actual overhead is closer to 80%.
In 3.05 I fixed the formulas, but I didn't change the default 42%,
which results in a smaller memory footprint, but slower programs.

Of course, you can even try 100% or more.  Depending on the program,
you might gain a lot of time before you hit the point of diminishing
returns.

If you want to recover the previous behaviour, you should set
something like OCAMLRUNPARAM=o=80.  In 3.06, it will be the default.

Sorry for the inconvenience,

-- Damien
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