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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: schwidefsky@de.ibm.com
Cc: Nick Piggin <nickpiggin@yahoo.com.au>,
	akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org
Subject: Re: [patch 3/3] arch_rebalance_pgtables call
Date: Wed, 14 Nov 2007 21:06:36 +1100	[thread overview]
Message-ID: <1195034796.28865.36.camel@pasglop> (raw)
In-Reply-To: <1195032394.9446.6.camel@localhost>


On Wed, 2007-11-14 at 10:26 +0100, Martin Schwidefsky wrote:
> That patch allows processes to have different number of page table
> levels, 31 bit processes have 2 levels (2GB), normal 64 bit processes
> have 3 levels (4TB) and really big 64 bit processes can have 4 levels
> (8PB). The downgrade of a page table to use less levels than the
> parent
> process is done in arch_pick_mmap_layout. The upgrade is done by using
> the arch_rebalance_pgtables call. I've considered using the
> arch_get_unmapped_area but got scared by the indirection in
> get_unmapped_area:
> 
>         get_area = current->mm->get_unmapped_area;
>         if (file && file->f_op && file->f_op->get_unmapped_area)
>                 get_area = file->f_op->get_unmapped_area;
>         addr = get_area(file, addr, len, pgoff, flags);

Don't be, it's really only hugetlb and other arch specific stuff that
hook in here on platforms with an MMU (It's also used by /dev/mem etc...
for mmu-less platforms but you don't care).

Ben.



  reply	other threads:[~2007-11-14 10:07 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-12 14:30 [patch 0/3] page table changes schwidefsky
2007-11-12 14:30 ` [patch 1/3] add mm argument to pte/pmd/pud/pgd_free schwidefsky
2007-11-12 14:30 ` [patch 2/3] CONFIG_HIGHPTE vs. sub-page page tables schwidefsky
2008-01-02 20:44   ` Christoph Hellwig
2008-01-02 21:24     ` Geert Uytterhoeven
2008-01-02 21:28       ` Benjamin Herrenschmidt
2008-01-03 13:12     ` Andi Kleen
2008-01-03 14:01       ` Boaz Harrosh
2008-02-01 23:15   ` Andrew Morton
2008-02-03  5:37     ` Benjamin Herrenschmidt
2008-02-03  5:53       ` Andrew Morton
2008-02-03  6:46         ` Ingo Molnar
2008-02-04 10:36         ` Martin Schwidefsky
2008-02-04 10:51           ` Andrew Morton
2008-02-04 11:02             ` Russell King
2008-02-04 11:14               ` Andrew Morton
2008-02-05 14:39             ` Martin Schwidefsky
2008-02-05 18:46               ` Andrew Morton
2008-02-06  9:06                 ` Martin Schwidefsky
2008-02-06  9:09                   ` Andrew Morton
2008-02-06  9:15                     ` Ingo Molnar
2008-02-06 15:50                     ` Martin Schwidefsky
2007-11-12 14:30 ` [patch 3/3] arch_rebalance_pgtables call schwidefsky
2007-11-13 12:33   ` Nick Piggin
2007-11-14  9:26     ` Martin Schwidefsky
2007-11-14 10:06       ` Benjamin Herrenschmidt [this message]
2007-11-14 11:49         ` Martin Schwidefsky
2007-11-14 22:07           ` Benjamin Herrenschmidt
2007-11-15 17:13             ` Martin Schwidefsky

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