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Date:	Wed, 23 Mar 2011 09:52:44 +0100
From:	Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: ld: fatal error - cmalloc would have returned NULL
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On Mar 23 09:37, Rainer Emrich wrote:
> On Mar 18 16:42, Corinna Vnschen wrote:
> >On Mar 18 10:56, Christopher Faylor wrote:
> >> On Fri, Mar 18, 2011 at 03:40:48PM +0100, Corinna Vinschen wrote:
> >> >On Mar 18 11:23, Corinna Vinschen wrote:
> >> >> In this case the bigger heap seems to avoid the aggressive use of small
> >> >> mmap chunks which in turn disallows to raise the cygheap size.  Without
> >> >> analyzing the whole situation there's not much else to say or do.  This
> >> >> is YA case which screams loudly for a testcase...
> >> >
> >> >I created an extensive testcase(*) and it turned out that the current
> >> >algorithm to allocate memory on the cygheap is wasting a lot of memory.
> >> >Actually it organizes the memory in buckets, each of which cares for a
> >> >specific size as a power of 2.  So memory on the cygheap is always
> >> >allocated in chunks of 4 byte, 8 byte, 16 byte, 32 byte, etc.  Plus,
> >> >every chunk needs extra 8 byte for bookkeeping.
> >>
> >> Right.  That's a fairly classic implementation of malloc which was, in
> >> this case, implemented by DJ Delorie.  I chose that from a few other
> >> implementations because it was, at the time, supposed to be the best
> >> tradeoff between speed and memory usage.  But, back when I implemented
> >> the cygheap it wasn't used as much as it is now, which I guess is
> >> fairly obvious.
> >
> >Maybe we should modify the implementation at one point, but for now I'm
> >wonderin if we shouldn't just raise the cygheap size to 2 Megs.  It's
> >still not much memory given today's RAM sizes, and it's only a fraction
> >of the application's address space.  But it is enough so that ld's
> >address space will be exhausted before the cygheap is exhausted.
> 
> I followed the discussion on the list and just tried the snapshot from 18th of
> March. This snapshot allows bootstrapping of gcc-4.5.0-1 including libjava.

Thanks for testing and thanks for this info!


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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