[Mono-osx] [Mono-dev] OS X builds and -DUSE-MUNMAP

[Allan Hsu]

On Jan 24, 2007, at 3:02 AM, Eoin Norris wrote:

The GC change is in SVN, but it hasn't been merged into the release  
tree. If you're using the official release packages, you won't see  
any improvement in GC behavior.

[...]
> This bloats to 200MB when reading a 23MB xml file - mostly in  
> doc.LoadXml(_libraryXmlString) as far as I can see ( although  
> without a full debugger it is hard to tell) . I have also would do  
> the same if it were read from disk at this point,   a process that  
> is too slow in any case, so I load in the Cocoa layer instead.

I suspect that this process causes a lot of temporary objects of  
varying sizes to be allocated. The current GC doesn't behave the best  
while allocating large chunks of memory, especially when this pattern  
is atypical for your application. It causes a lot of new pages to be  
allocated for objects of various sizes that will be unlikely to be  
used again in the lifetime of your application.

[...]
>
>  Were I to download the sources, where should I look to see if this  
> is in the suggested sources i.e. 1.2.2.1 ? Is there a way to tell  
> from the dlls ( I suspect not).
>

This is the relevant part of configure.in:

	*-*-darwin*)
		platform_win32=no
		CPPFLAGS="$CPPFLAGS -no-cpp-precomp -D_THREAD_SAFE - 
DGC_MACOSX_THREADS -DPLATFORM_MACOSX -DUSE_MMAP -DUSE_MUNMAP"

If you compare the release tarball to the one in SVN, you can see  
that the release doesn't turn these flags on.

> I should add this is really a deal breaker in terms of releasing  
> the product, as you can imagine not releasing large amounts of  
> memory is a big issue.

Yes. Yes it is. I'm not sure why the change hasn't made it into  
release tree. You'll have to ask somebody like Miguel or Wade about  
this.

	-Allan
--
Allan Hsu <allan at counterpop dot net>
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