From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: benh@kernel.crashing.org
Cc: linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-s390@vger.kernel.org, borntraeger@de.ibm.com
Subject: Re: [patch 2/6] CONFIG_HIGHPTE vs. sub-page page tables.
Date: Fri, 26 Oct 2007 10:08:20 +0200 [thread overview]
Message-ID: <1193386100.31831.13.camel@localhost> (raw)
In-Reply-To: <1193385617.13638.3.camel@pasglop>
On Fri, 2007-10-26 at 18:00 +1000, Benjamin Herrenschmidt wrote:
> > > Interesting. That means I don't need to have a PTE page to be a struct
> > > page anymore ? I can have good use for that on powerpc as well...
> >
> > That would be good news. I'm curious, can you elaborate on what the use
> > case is?
>
> When using 64K pages, we use 32K of PTEs and 32K of "extension". The
> extension thing is used when using HW 4K pages, to keep track of the
> subpages. On setups where that isn't needed, we can save memory by
> allocating half pages...
Ahh, that is exactly the same reason as for s390. Page tables with a
size that is sub-page.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
WARNING: multiple messages have this Message-ID (diff)
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: benh@kernel.crashing.org
Cc: linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-s390@vger.kernel.org, borntraeger@de.ibm.com
Subject: Re: [patch 2/6] CONFIG_HIGHPTE vs. sub-page page tables.
Date: Fri, 26 Oct 2007 10:08:20 +0200 [thread overview]
Message-ID: <1193386100.31831.13.camel@localhost> (raw)
In-Reply-To: <1193385617.13638.3.camel@pasglop>
On Fri, 2007-10-26 at 18:00 +1000, Benjamin Herrenschmidt wrote:
> > > Interesting. That means I don't need to have a PTE page to be a struct
> > > page anymore ? I can have good use for that on powerpc as well...
> >
> > That would be good news. I'm curious, can you elaborate on what the use
> > case is?
>
> When using 64K pages, we use 32K of PTEs and 32K of "extension". The
> extension thing is used when using HW 4K pages, to keep track of the
> subpages. On setups where that isn't needed, we can save memory by
> allocating half pages...
Ahh, that is exactly the same reason as for s390. Page tables with a
size that is sub-page.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
--
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next prev parent reply other threads:[~2007-10-26 8:08 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-25 18:15 [patch 0/6] s390 page tables on steroids Martin Schwidefsky
2007-10-25 18:15 ` Martin Schwidefsky
2007-10-25 18:15 ` [patch 1/6] add mm argument to pte/pmd/pud/pgd_free Martin Schwidefsky
2007-10-25 18:15 ` Martin Schwidefsky, Benjamin Herrenschmidt, Martin Schwidefsky
2007-10-25 18:15 ` [patch 2/6] CONFIG_HIGHPTE vs. sub-page page tables Martin Schwidefsky
2007-10-25 18:15 ` Martin Schwidefsky, Martin Schwidefsky
2007-10-25 20:47 ` Benjamin Herrenschmidt
2007-10-25 20:47 ` Benjamin Herrenschmidt
2007-10-26 7:42 ` Martin Schwidefsky
2007-10-26 7:42 ` Martin Schwidefsky
2007-10-26 8:00 ` Benjamin Herrenschmidt
2007-10-26 8:00 ` Benjamin Herrenschmidt
2007-10-26 8:08 ` Martin Schwidefsky [this message]
2007-10-26 8:08 ` Martin Schwidefsky
2007-10-26 8:06 ` Martin Schwidefsky
2007-10-26 8:06 ` Martin Schwidefsky
2007-10-25 18:15 ` [patch 3/6] arch_update_pgd call Martin Schwidefsky
2007-10-25 18:15 ` Martin Schwidefsky, Martin Schwidefsky
2007-10-25 20:48 ` Benjamin Herrenschmidt
2007-10-25 20:48 ` Benjamin Herrenschmidt
2007-10-25 22:49 ` Benjamin Herrenschmidt
2007-10-25 22:49 ` Benjamin Herrenschmidt
2007-10-26 7:40 ` Martin Schwidefsky
2007-10-26 7:40 ` Martin Schwidefsky
2007-10-26 7:59 ` Benjamin Herrenschmidt
2007-10-26 7:59 ` Benjamin Herrenschmidt
2007-10-26 8:22 ` Martin Schwidefsky
2007-10-26 8:22 ` Martin Schwidefsky
2007-10-26 11:28 ` Benjamin Herrenschmidt
2007-10-26 11:28 ` Benjamin Herrenschmidt
2007-10-25 18:15 ` [patch 4/6] s390: 1K/2K page table pages Martin Schwidefsky
2007-10-25 18:15 ` Martin Schwidefsky, Martin Schwidefsky
2007-10-25 18:15 ` [patch 5/6] s390: Add four level page tables for CONFIG_64BIT=y Martin Schwidefsky
2007-10-25 18:15 ` Martin Schwidefsky, Martin Schwidefsky
2007-10-25 18:15 ` [patch 6/6] s390: dynamic page tables Martin Schwidefsky
2007-10-25 18:15 ` Martin Schwidefsky, Martin Schwidefsky
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