From: Roland Dreier <rdreier@cisco.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>, Frans Pop <elendil@planet.nl>,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: Unable to continue testing of 2.6.25
Date: Mon, 18 Feb 2008 11:18:48 -0800 [thread overview]
Message-ID: <adahcg6jco7.fsf@cisco.com> (raw)
In-Reply-To: <20080218110706.221d3015@laptopd505.fenrus.org> (Arjan van de Ven's message of "Mon, 18 Feb 2008 11:07:06 -0800")
> > AFAIK mapping PCI memory WB is not allowed, so WC is really our only
> > choice.
> afaik that depends on the BAR being prefetchable or not.
In my case the BAR is prefetchable.
> (and by your argument, ioremap_cached() would not be useful, and since that was, until
> 2.6.25-rc1, the default behavior for ioremap(), would have caused massive problems)
I'm not sure what ioremap_cached() would really do in my case, since
the MTRRs for PCI memory are set to UC, so without monkeying with MTRR
contents (which can't really be done safely) the only choices we have
are leaving the mapping as UC or using PAT to get WC.
Also in my case I'm more concerned about latency of finishing a small
write rather than througput. So I'm not sure that I would really want
to do a write to a WB mapping followed by CLFLUSH anyway.
- R.
next prev parent reply other threads:[~2008-02-18 19:19 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-17 9:25 Unable to continue testing of 2.6.25 Frans Pop
2008-02-17 13:16 ` Adrian Bunk
2008-02-17 19:24 ` Tilman Schmidt
2008-02-17 19:44 ` Adrian Bunk
2008-02-17 20:38 ` Paul Jackson
2008-02-17 20:51 ` Arjan van de Ven
2008-02-19 22:41 ` Frans Pop
2008-02-18 2:33 ` David Miller
2008-02-18 11:40 ` Tilman Schmidt
2008-02-18 12:27 ` Andi Kleen
2008-02-19 21:55 ` Frans Pop
2008-02-19 21:59 ` Arjan van de Ven
2008-02-19 22:15 ` Harvey Harrison
2008-02-19 22:19 ` Adrian Bunk
2008-02-19 22:49 ` Frans Pop
2008-02-17 20:46 ` Arjan van de Ven
2008-02-18 12:31 ` Andi Kleen
2008-02-18 16:50 ` Arjan van de Ven
2008-02-18 17:11 ` Andi Kleen
2008-02-18 17:32 ` Arjan van de Ven
2008-02-18 18:40 ` Alan Cox
2008-02-18 18:52 ` Arjan van de Ven
2008-02-18 20:15 ` Alan Cox
2008-02-18 18:52 ` Andi Kleen
2008-02-18 18:32 ` Arjan van de Ven
2008-02-18 19:18 ` Ingo Molnar
2008-02-19 9:35 ` Andi Kleen
2008-02-18 18:53 ` Roland Dreier
2008-02-18 19:07 ` Arjan van de Ven
2008-02-18 19:18 ` Roland Dreier [this message]
2008-02-19 19:42 ` Siddha, Suresh B
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