[fpc-devel] Need heap manager -gv explanation

[Petr Kristan]

On Mon, Apr 28, 2014 at 06:12:18PM +0200, Tomas Hajny wrote:
> On Mon, April 28, 2014 17:56, Mattias Gaertner wrote:
> > On Mon, 28 Apr 2014 17:20:17 +0200
> > Petr Kristan <petr.kristan at epos.cz> wrote:
> >
> >> Hi
> >>
> >> I have some application with huge usage ReAllocMem and I found the big
> >> performance difference if application is compiled with -gv option (cca
> >> 20x faster) then without -gv option.
> >
> > -gv generates code for valgrind.
> > It should be slower with -gv.
> >
> >> I suspect fpc heap manager. Is possible to tune fpc heap manager?
> >> Is some difference in heap manager if application is comiled with -gv or
> >> without -gv option?
> 
> Use of valgrind requires/triggers use of cmem. Depending on the particular
> use case (and potentially also the target platform), cmem may indeed be
> faster.
Platform is x86_64 Linux.

> Others would be better positioned for more detailed comparison among
> various heap managers with regard to speed in different use cases, overall
> memory requirements achieved by reuse of previously allocated memory, etc.
Reuse of previously allocated memory - it really can be my problem.
Here is about 200x call ReAllocMem increasing buffer from 4kB to 80MB.

It looks like as buffer is increasing ReAllocMem is slowing.
But I must verify this feeling.

Petr

-- 
Petr Kristan
.
EPOS PRO s.r.o., Smilova 333, 530 02 Pardubice
tel: +420 461101401    Czech Republic (Eastern Europe)
fax: +420 461101481