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From: "David S. Miller" <davem@davemloft.net>
From: Andi Kleen <ak@suse.de>
To: ak@suse.de
Cc: alan@lxorguk.ukuu.org.uk, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, nickpiggin@yahoo.com.au
Subject: Re: [PATCH 2.6.13] lockless pagecache 2/7
Date: Fri, 02 Sep 2005 14:12:55 -0700 (PDT)	[thread overview]
Date: 02 Sep 2005 22:41:31 +0200	[thread overview]
Message-ID: <20050902.141255.50099210.davem@davemloft.net> (raw)
In-Reply-To: <p73k6hzqk1w.fsf@verdi.suse.de>

> > Yeah quite a few. I suspect most MIPS also would have a problem in this
> > area.
> 
> cmpxchg can be done with LL/SC can't it? Any MIPS should have that.

Right.

On PARISC, I don't see where they are emulating compare and swap
as indicated.  They are doing the funny hashed spinlocks for the
atomic_t operations and bitops, but that is entirely different.

cmpxchg() has to operate in an environment where, unlike the atomic_t
and bitops, you cannot control the accessors to the object at all.

The DRM is the only place in the kernel that requires cmpxchg()
and you can thus make a list of what platform can provide cmpxchg()
by which ones support DRM and thus provide the cmpxchg() macro already
in asm/system.h

We really can't require support for this primitive kernel wide, it's
simply not possible on a couple chips.
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  reply	other threads:[~2005-09-02 21:12 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-02  6:25 New lockless pagecache Nick Piggin
2005-09-02  6:28 ` [PATCH 2.6.13] lockless pagecache 1/7 Nick Piggin
2005-09-02  6:29   ` [PATCH 2.6.13] lockless pagecache 2/7 Nick Piggin
2005-09-02  6:30     ` [PATCH 2.6.13] lockless pagecache 3/7 Nick Piggin
2005-09-02  6:30       ` [PATCH 2.6.13] lockless pagecache 4/7 Nick Piggin
2005-09-02  6:31         ` [PATCH 2.6.13] lockless pagecache 5/7 Nick Piggin
2005-09-02  6:32           ` [PATCH 2.6.13] lockless pagecache 6/7 Nick Piggin
2005-09-02  6:32             ` [PATCH 2.6.13] lockless pagecache 7/7 Nick Piggin
2005-09-09 13:00               ` Christoph Lameter
2005-09-09 15:23                 ` Nick Piggin
2005-09-09  5:36           ` [PATCH 2.6.13] lockless pagecache 5/7 Christoph Lameter
2005-09-09  6:22             ` Nick Piggin
2005-09-02 13:08     ` [PATCH 2.6.13] lockless pagecache 2/7 Alan Cox
2005-09-02 20:41       ` Andi Kleen
2005-09-02 21:12         ` David S. Miller, Andi Kleen [this message]
2005-09-02 21:43           ` Nick Piggin
2005-09-02 21:22         ` Nick Piggin
2005-09-02 21:31           ` David S. Miller, Nick Piggin
2005-09-02 21:47             ` Nick Piggin
2005-09-02 21:57               ` David S. Miller, Nick Piggin
2005-09-02 23:57           ` Alan Cox
2005-09-03  1:40             ` Nick Piggin
2005-09-03 17:31               ` Alan Cox
2005-09-04  1:01                 ` Nick Piggin
2005-09-04  8:20                   ` Alan Cox
2005-09-06  1:03                     ` Nick Piggin
2005-09-02 18:26     ` Christoph Lameter
2005-09-02 21:26       ` Nick Piggin
2005-09-03  1:33         ` Christoph Lameter
2005-09-02  6:45 ` New lockless pagecache Nick Piggin
2005-09-15 19:50   ` Alok kataria
2005-09-16  3:12     ` Nick Piggin

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