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Date:      Thu, 8 Nov 2001 18:00:27 +0000 (GMT)
From:      Doug Rabson <dfr@nlsystems.com>
To:        Peter Wemm <peter@wemm.org>
Cc:        Marcel Moolenaar <marcel@xcllnt.net>, <ia64@FreeBSD.ORG>
Subject:   Re: Region usage 
Message-ID:  <Pine.BSF.4.33.0111081757590.89493-100000@herring.nlsystems.com>
In-Reply-To: <20011108174026.F0A953807@overcee.netplex.com.au>

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On Thu, 8 Nov 2001, Peter Wemm wrote:

> Doug Rabson wrote:
> > On Wed, 7 Nov 2001, Marcel Moolenaar wrote:
> >
> > > On Wed, Nov 07, 2001 at 10:13:48AM +0000, Doug Rabson wrote:
> [..]
> > > > A truly 'large' application can always overflow into the other regions.
> > >
> > > The question is if this can be done automagically or if it requires
> > > compile-time options or even ELF object tuning (ie flags).
> >
> > This would happen automatically. If the elf sections were rooted in
> > specific regions, the loader would automatically put them there and the VM
> > system would allocate spaces as required. If a running app wants to use a
> > new region, its as simple as giving an explicit address to mmap(2).
>
> There appears to be some bugs here right now.  I was able to mmap over
> 4500TB of data files into a single region, which is bigger than the number
> of bits implemented in a region. (2^51 on the itanium if I recall
> correctly)  I dont think it should have returned addresses above 2048TB in
> the region.

Yes... I'm not sure how hard it will be to teach the VM system about the
discontiguous virtual address space.

>
> Secondly, pressing ^C takes quite some time..  I think its spending its
> time in pmap_invalidate_all()..  This is with interrupts disabled.
> (where quite some time == ~10 minutes with a an 8TB file mmaped).

The various pmap_remove() variants are not very efficient right now. After
I get the thing to actually work reliably, I'll come back and fix that.

-- 
Doug Rabson				Mail:  dfr@nlsystems.com
					Phone: +44 20 8348 6160



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