Mail Archives: cygwin/2006/08/14/02:59:12
On Aug 13 11:23, Reini Urban wrote:
> Corinna Vinschen schrieb:
> ...
> >Ok, back to mmap/munmap. Private anonymous mappings are implemented in
> >Cygwin by calling VirtualAlloc/VirtualFree. However, due to
> >restrictions in the Win32 API, VirtualFree is only called by munmap, as
> >soon as *all* pages within a single mmap'ed area are free'ed by this or
> >preceding calls to munmap.
> >
> >In other words, the mmap'ed memory will not be returned to the OS, if
> >not the complete mmap'ed area is munmap'ed. Therefore I assume that the
> >implementation in Lisp keeps bits of memory around which are not
> >munmap'ed for some internal reason.
> >
> >Of course it's also possible that there's a bug in Cygwin related to the
> >way mmap/munmap is called. But I have so far no evidence for that and
> >simple mmap/munmap tests show that VirtualFree is called as soon as all
> >pages in a mmap'ed area have been munmap'ed. If somebody thinks there's
> >a bug in this implementation, please send a simple, self-contained
> >testcase in pure C source code, which allows to reproduce the problem.
> >Of course, patches are welcome, too :)
>
> And there's the known mmap() under cygwin limitation, esp. harmful to
> clisp, that mmap() can only be properly aligned to a base address modulo
> 64k (windows "allocation granularity"), and not the usual pagesize, if
> it's 4k or 8k. windows pagesize is still 4k though.
>
> http://www.cygwin.com/ml/cygwin/2000-09/msg00380.html
> http://www.cygwin.com/ml/cygwin/2004-09/msg00741.html
This is a non-issue since 1.5.19:
http://cygwin.com/ml/cygwin-announce/2006-01/msg00016.html
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader cygwin AT cygwin DOT com
Red Hat
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