From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Shan Hai <haishan.bai@gmail.com>,
paulus@samba.org, tglx@linutronix.de, walken@google.com,
dhowells@redhat.com, cmetcalf@tilera.com, tony.luck@intel.com,
akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] Fixup write permission of TLB on powerpc e500 core
Date: Sun, 17 Jul 2011 13:02:41 +0200 [thread overview]
Message-ID: <1310900561.13765.22.camel@twins> (raw)
In-Reply-To: <1310860194.25044.17.camel@pasglop>
On Sun, 2011-07-17 at 09:49 +1000, Benjamin Herrenschmidt wrote:
> In the meantime, other than rewriting the futex code to not require
> those in-atomic accesses (can't it just access the pages via the linear
> mapping and/or kmap after the gup ?),
That'll wreck performance on things like ARM and SPARC that have to deal
with cache aliasing.
> all I see would be a way to force
> dirty and young after gup, with appropriate locks, or a variant of gup
> (via a flag ?) to require it to do so.
Again, _WHY_ isn't gup(.write=1) a complete write fault? Its supposed to
be, it needs to break COW, do dirty page tracking and call page_mkwrite.
I'm still thinking this e500 stuff is smoking crack.
ARM has no hardware dirty bit either, and yet it works for them. I can't
exactly tell how because I got lost in there, but it does, again,
suggest e500 is on crack.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: tony.luck@intel.com, Shan Hai <haishan.bai@gmail.com>,
linux-kernel@vger.kernel.org, cmetcalf@tilera.com,
dhowells@redhat.com, paulus@samba.org, tglx@linutronix.de,
walken@google.com, linuxppc-dev@lists.ozlabs.org,
akpm@linux-foundation.org
Subject: Re: [PATCH 1/1] Fixup write permission of TLB on powerpc e500 core
Date: Sun, 17 Jul 2011 13:02:41 +0200 [thread overview]
Message-ID: <1310900561.13765.22.camel@twins> (raw)
In-Reply-To: <1310860194.25044.17.camel@pasglop>
On Sun, 2011-07-17 at 09:49 +1000, Benjamin Herrenschmidt wrote:
> In the meantime, other than rewriting the futex code to not require
> those in-atomic accesses (can't it just access the pages via the linear
> mapping and/or kmap after the gup ?),
That'll wreck performance on things like ARM and SPARC that have to deal
with cache aliasing.
> all I see would be a way to force
> dirty and young after gup, with appropriate locks, or a variant of gup
> (via a flag ?) to require it to do so.=20
Again, _WHY_ isn't gup(.write=3D1) a complete write fault? Its supposed to
be, it needs to break COW, do dirty page tracking and call page_mkwrite.
I'm still thinking this e500 stuff is smoking crack.
ARM has no hardware dirty bit either, and yet it works for them. I can't
exactly tell how because I got lost in there, but it does, again,
suggest e500 is on crack.
next prev parent reply other threads:[~2011-07-17 11:03 UTC|newest]
Thread overview: 138+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-15 8:07 [PATCH 0/1] Fixup write permission of TLB on powerpc e500 core Shan Hai
2011-07-15 8:07 ` Shan Hai
2011-07-15 8:07 ` [PATCH 1/1] " Shan Hai
2011-07-15 8:07 ` Shan Hai
2011-07-15 10:23 ` Peter Zijlstra
2011-07-15 10:23 ` Peter Zijlstra
2011-07-15 15:18 ` Shan Hai
2011-07-15 15:18 ` Shan Hai
2011-07-15 15:24 ` Peter Zijlstra
2011-07-15 15:24 ` Peter Zijlstra
2011-07-16 15:36 ` Shan Hai
2011-07-16 15:36 ` Shan Hai
2011-07-16 14:50 ` Shan Hai
2011-07-16 14:50 ` Shan Hai
2011-07-16 23:49 ` Benjamin Herrenschmidt
2011-07-16 23:49 ` Benjamin Herrenschmidt
2011-07-17 9:38 ` Peter Zijlstra
2011-07-17 9:38 ` Peter Zijlstra
2011-07-17 14:29 ` Benjamin Herrenschmidt
2011-07-17 14:29 ` Benjamin Herrenschmidt
2011-07-17 23:14 ` Benjamin Herrenschmidt
2011-07-17 23:14 ` Benjamin Herrenschmidt
2011-07-18 3:53 ` Benjamin Herrenschmidt
2011-07-18 3:53 ` Benjamin Herrenschmidt
2011-07-18 4:02 ` Benjamin Herrenschmidt
2011-07-18 4:02 ` Benjamin Herrenschmidt
2011-07-18 4:01 ` Benjamin Herrenschmidt
2011-07-18 4:01 ` Benjamin Herrenschmidt
2011-07-18 6:48 ` Shan Hai
2011-07-18 6:48 ` Shan Hai
2011-07-18 7:01 ` Benjamin Herrenschmidt
2011-07-18 7:01 ` Benjamin Herrenschmidt
2011-07-18 7:26 ` Shan Hai
2011-07-18 7:26 ` Shan Hai
2011-07-18 7:36 ` Benjamin Herrenschmidt
2011-07-18 7:36 ` Benjamin Herrenschmidt
2011-07-18 7:50 ` Shan Hai
2011-07-18 7:50 ` Shan Hai
2011-07-19 3:30 ` Shan Hai
2011-07-19 3:30 ` Shan Hai
2011-07-19 4:20 ` Benjamin Herrenschmidt
2011-07-19 4:20 ` Benjamin Herrenschmidt
2011-07-19 4:29 ` [RFC/PATCH] mm/futex: Fix futex writes on archs with SW tracking of dirty & young Benjamin Herrenschmidt
2011-07-19 4:29 ` Benjamin Herrenschmidt
2011-07-19 4:55 ` Shan Hai
2011-07-19 4:55 ` Shan Hai
2011-07-19 5:17 ` Shan Hai
2011-07-19 5:17 ` Shan Hai
2011-07-19 5:24 ` Benjamin Herrenschmidt
2011-07-19 5:24 ` Benjamin Herrenschmidt
2011-07-19 5:38 ` Shan Hai
2011-07-19 5:38 ` Shan Hai
2011-07-19 7:46 ` Benjamin Herrenschmidt
2011-07-19 7:46 ` Benjamin Herrenschmidt
2011-07-19 8:24 ` Shan Hai
2011-07-19 8:24 ` Shan Hai
2011-07-19 8:26 ` [RFC/PATCH] mm/futex: Fix futex writes on archs with SW trackingof " David Laight
2011-07-19 8:26 ` David Laight
2011-07-19 8:45 ` Benjamin Herrenschmidt
2011-07-19 8:45 ` Benjamin Herrenschmidt
2011-07-19 8:45 ` Shan Hai
2011-07-19 8:45 ` Shan Hai
2011-07-19 11:10 ` [RFC/PATCH] mm/futex: Fix futex writes on archs with SW tracking of " Peter Zijlstra
2011-07-19 11:10 ` Peter Zijlstra
2011-07-20 14:39 ` Darren Hart
2011-07-20 14:39 ` Darren Hart
2011-07-21 22:36 ` Andrew Morton
2011-07-21 22:36 ` Andrew Morton
2011-07-21 22:52 ` Benjamin Herrenschmidt
2011-07-21 22:52 ` Benjamin Herrenschmidt
2011-07-21 22:57 ` Benjamin Herrenschmidt
2011-07-21 22:57 ` Benjamin Herrenschmidt
2011-07-21 22:59 ` Andrew Morton
2011-07-21 22:59 ` Andrew Morton
2011-07-22 1:40 ` Benjamin Herrenschmidt
2011-07-22 1:40 ` Benjamin Herrenschmidt
2011-07-22 1:54 ` Shan Hai
2011-07-22 1:54 ` Shan Hai
2011-07-27 6:50 ` Mike Frysinger
2011-07-27 6:50 ` Mike Frysinger
2011-07-27 7:58 ` Benjamin Herrenschmidt
2011-07-27 7:58 ` Benjamin Herrenschmidt
2011-07-27 8:59 ` Peter Zijlstra
2011-07-27 8:59 ` Peter Zijlstra
2011-07-27 10:09 ` David Howells
2011-07-27 10:09 ` David Howells
2011-07-27 10:17 ` Peter Zijlstra
2011-07-27 10:17 ` Peter Zijlstra
2011-07-27 10:20 ` Benjamin Herrenschmidt
2011-07-27 10:20 ` Benjamin Herrenschmidt
2011-07-28 0:12 ` Mike Frysinger
2011-07-28 0:12 ` Mike Frysinger
2011-08-08 2:31 ` Mike Frysinger
2011-08-08 2:31 ` Mike Frysinger
2011-07-28 10:55 ` David Howells
2011-07-28 10:55 ` David Howells
2011-07-17 11:02 ` Peter Zijlstra [this message]
2011-07-17 11:02 ` [PATCH 1/1] Fixup write permission of TLB on powerpc e500 core Peter Zijlstra
2011-07-17 13:33 ` Shan Hai
2011-07-17 13:33 ` Shan Hai
2011-07-17 14:48 ` Benjamin Herrenschmidt
2011-07-17 14:48 ` Benjamin Herrenschmidt
2011-07-17 15:40 ` Shan Hai
2011-07-17 15:40 ` Shan Hai
2011-07-17 22:34 ` Benjamin Herrenschmidt
2011-07-17 22:34 ` Benjamin Herrenschmidt
2011-07-17 14:34 ` Benjamin Herrenschmidt
2011-07-17 14:34 ` Benjamin Herrenschmidt
2011-07-15 8:20 ` [PATCH 0/1] " Peter Zijlstra
2011-07-15 8:20 ` Peter Zijlstra
2011-07-15 8:38 ` MailingLists
2011-07-15 8:38 ` MailingLists
2011-07-15 8:44 ` Peter Zijlstra
2011-07-15 8:44 ` Peter Zijlstra
2011-07-15 9:08 ` Shan Hai
2011-07-15 9:08 ` Shan Hai
2011-07-15 9:12 ` Benjamin Herrenschmidt
2011-07-15 9:12 ` Benjamin Herrenschmidt
2011-07-15 9:50 ` Peter Zijlstra
2011-07-15 9:50 ` Peter Zijlstra
2011-07-15 10:06 ` Shan Hai
2011-07-15 10:06 ` Shan Hai
2011-07-15 10:32 ` David Laight
2011-07-15 10:32 ` David Laight
2011-07-15 10:39 ` Peter Zijlstra
2011-07-15 10:39 ` Peter Zijlstra
2011-07-15 15:32 ` Shan Hai
2011-07-15 15:32 ` Shan Hai
2011-07-16 0:20 ` Benjamin Herrenschmidt
2011-07-16 0:20 ` Benjamin Herrenschmidt
2011-07-16 15:03 ` Shan Hai
2011-07-16 15:03 ` Shan Hai
2011-07-15 23:47 ` Benjamin Herrenschmidt
2011-07-15 23:47 ` Benjamin Herrenschmidt
2011-07-15 9:07 ` Benjamin Herrenschmidt
2011-07-15 9:07 ` Benjamin Herrenschmidt
2011-07-15 9:05 ` Benjamin Herrenschmidt
2011-07-15 9:05 ` Benjamin Herrenschmidt
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