From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Segher Boessenkool <segher@kernel.crashing.org>,
Jesse Barnes <jbarnes@virtuousgeek.org>,
David Miller <davem@davemloft.net>,
jeff@garzik.org, paulus@samba.org, torvalds@osdl.org,
linux-kernel@vger.kernel.org, akpm@osdl.org
Subject: Re: Opinion on ordering of writel vs. stores to RAM
Date: Mon, 11 Sep 2006 10:02:52 +0100 [thread overview]
Message-ID: <1157965372.23085.87.camel@localhost.localdomain> (raw)
In-Reply-To: <1157933531.31071.274.camel@localhost.localdomain>
Ar Llu, 2006-09-11 am 10:12 +1000, ysgrifennodd Benjamin Herrenschmidt:
> - writel/readl are fully synchronous (minus mmiowb for spinlocks)
> - we provide __writel/__readl with some barriers with relaxed ordering
> between memory and MMIO (though still _precise_ semantics, not arch
> specific)
I'd rather they were less precise than your later proposal but that
reflects the uses I'm considering perhaps.
> * Option B:
>
> - The driver decides at ioremap time wether it wants a fully ordered
> mapping or not using
That is expensive because writel/readl end up full of if() while at the
moment they are often 1 instruction.
next prev parent reply other threads:[~2006-09-11 8:40 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-09 2:03 Opinion on ordering of writel vs. stores to RAM Paul Mackerras
2006-09-09 2:42 ` Linus Torvalds
2006-09-09 3:02 ` Paul Mackerras
2006-09-09 3:54 ` Linus Torvalds
2006-09-09 7:24 ` Benjamin Herrenschmidt
2006-09-09 9:34 ` David Miller
2006-09-09 9:55 ` Jeff Garzik
2006-09-09 10:08 ` David Miller
2006-09-10 17:18 ` Jesse Barnes
2006-09-10 19:35 ` Alan Cox
2006-09-10 21:25 ` Benjamin Herrenschmidt
2006-09-10 22:23 ` Alan Cox
2006-09-10 22:18 ` Benjamin Herrenschmidt
2006-09-11 13:19 ` Jes Sorensen
2006-09-10 23:35 ` Segher Boessenkool
2006-09-11 0:12 ` Benjamin Herrenschmidt
2006-09-11 0:34 ` Jesse Barnes
2006-09-11 1:04 ` Benjamin Herrenschmidt
2006-09-11 1:13 ` Segher Boessenkool
2006-09-11 1:35 ` Benjamin Herrenschmidt
2006-09-11 9:02 ` Alan Cox [this message]
2006-09-11 9:23 ` Benjamin Herrenschmidt
2006-09-11 0:25 ` Jesse Barnes
2006-09-11 0:54 ` Segher Boessenkool
2006-09-11 1:10 ` Benjamin Herrenschmidt
2006-09-11 1:48 ` Segher Boessenkool
2006-09-11 3:53 ` Benjamin Herrenschmidt
2006-09-11 18:12 ` Jesse Barnes
2006-09-11 1:00 ` Benjamin Herrenschmidt
2006-09-11 18:08 ` Jesse Barnes
2006-09-11 21:32 ` Benjamin Herrenschmidt
2006-09-10 20:01 ` Segher Boessenkool
2006-09-11 13:21 ` David Miller
2006-09-11 14:17 ` Segher Boessenkool
2006-09-12 0:32 ` David Miller
2006-09-12 0:49 ` Benjamin Herrenschmidt
2006-09-12 16:47 ` Segher Boessenkool
2006-09-12 0:54 ` Roland Dreier
2006-09-09 11:16 ` Paul Mackerras
2006-09-09 7:23 ` Benjamin Herrenschmidt
2006-09-09 9:38 ` David Miller
2006-09-09 15:09 ` Alan Cox
2006-09-10 17:19 ` Jesse Barnes
2006-09-10 17:35 ` Michael Buesch
2006-09-10 17:49 ` Linus Torvalds
2006-09-10 18:02 ` Michael Buesch
2006-09-09 15:08 ` Alan Cox
2006-09-09 18:34 ` Auke Kok
2006-09-09 19:10 ` Patrick McFarland
2006-09-09 15:06 ` Alan Cox
-- strict thread matches above, loose matches on Subject: below --
2006-09-11 5:03 Michael Chan
2006-09-11 5:21 ` Benjamin Herrenschmidt
2006-09-12 4:30 Albert Cahalan
2006-09-12 5:30 ` Benjamin Herrenschmidt
2006-09-12 6:04 ` Albert Cahalan
2006-09-12 6:12 ` Benjamin Herrenschmidt
2006-09-12 7:09 ` Albert Cahalan
2006-09-12 7:17 ` Benjamin Herrenschmidt
2006-09-12 7:21 ` Albert Cahalan
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