[fpc-devel] Forwarded message about FPC statusy

Florian Klaempfl florian at freepascal.org
Tue Dec 25 15:08:09 CET 2012

Am 25.12.2012 14:59, schrieb Yury Sidorov:
> From: "Yury Sidorov" <jura at cp-lab.com>
>> From: "Florian Klaempfl" <florian at freepascal.org>
>>> Am 25.12.2012 13:39, schrieb Yury Sidorov:
>>>> It is possible to seed-up compilation by allocating memory for nodes
>>>> from some zero pre-filled memory pool to avoid costly calls to heap
>>>> manager and avoid zero filling of small memory chunks. A base class for
>>>> various FPC nodes should be modified to handle aloocation from the
>>>> pool...
>>> The heap manager itself does already pooling so I don't see much gain
>>> in doing so ...
>> Still zero-filling a million of small memory chunks is very time
>> consuming. It is better to pre-zerofill big pool blocks first and then
>> assueme that memory already zero fillled in custom object init code.
>> Although FPC heap manager is good, but custom pool memory allocation
>> will be much faster, since it will be very simple:
>>  Result:=CurPoolPtr;
>>  Inc(CurPoolPtr, BlockSize);
>>  if CurPoolPtr > MaxPoolPtr then AllocNewZeroFilledPool();
>> It is not needed to handle memory releases during object destruction.
>> Since all nodes are available during whole compiling phase (parsing,
>> code generation, etc) and released only at the end of a phase, it is
>> possible just to release whole pool blocks at the end of a phase.
>> Such pooled base class for compiler nodes should inrease performanse a
>> lot.
> Hmm, Seems to be a false alarm :(
> I've made some tests just now with memory allocation and found that such
> pooling will not speed up the compiler too much. Only minor improvement
> such as 10-20% :(

Ops, messages crossed :) I'd expect no more. One thing might be to 
rewrite the whole unit handling so that symtables etc. can be 
read/written as one block to PPUs but doing so might be also pretty time 
consuming and I doubt the maintainability of such an approach.

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