From: Grant Grundler <grundler@parisc-linux.org>
To: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Matthew Wilcox <matthew@wil.cx>,
parisc-linux <parisc-linux@lists.parisc-linux.org>,
Thibaut VARENE <T-Bone@parisc-linux.org>
Subject: Re: [parisc-linux] The problem on the PA8800 is all in the data-cache.
Date: Mon, 24 Jul 2006 10:32:28 -0600 [thread overview]
Message-ID: <20060724163228.GA22560@colo.lackof.org> (raw)
In-Reply-To: <1153750204.1235.18.camel@mulgrave.il.steeleye.com>
On Mon, Jul 24, 2006 at 09:10:04AM -0500, James Bottomley wrote:
> What Matthew means is that the L2 cache is PIPT ... you can't get
> aliasing effects in a PIPT cache, so for the purposes of the problem it
> must be ignorable, since we can only get aliasing effects in the L1
> cache which is VIPT.
While I agree in general that a PIPT cache won't have aliasing effects.
ISTR the virtual coherence index (VCI) is part of the "physical address".
If it's not, I'm confused how CPUs on different sockets remain coherent.
I expect the VCI is visible across the Mckinley Bus and thus is part
of the physical address. IOMMU is also pushing out an address that
has VCI bits in it - so DMA remains coherent with CPU virtual addresses.
If I've got this right, then we can have aliasing in PIPT cache.
Willy, can you check the pa8800 ERS and look for "coherence index"
or similar, related words?
thanks,
grant
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next prev parent reply other threads:[~2006-07-24 16:32 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-22 17:50 [parisc-linux] The problem on the PA8800 is all in the data-cache Carlos O'Donell
2006-07-23 1:01 ` Thibaut VARENE
2006-07-23 16:28 ` Michael S. Zick
2006-07-23 22:03 ` Thibaut VARENE
2006-07-24 1:40 ` Kyle McMartin
2006-07-24 2:39 ` Thibaut VARENE
2006-07-24 2:33 ` James Bottomley
2006-07-24 2:54 ` Thibaut VARENE
2006-07-24 3:32 ` Matthew Wilcox
2006-07-24 4:15 ` Thibaut VARENE
[not found] ` <1153750204.1235.18.camel@mulgrave.il.steeleye.com>
2006-07-24 16:32 ` Grant Grundler [this message]
2006-07-25 14:51 ` James Bottomley
2006-07-25 16:13 ` John David Anglin
2006-07-25 16:17 ` James Bottomley
2006-07-25 16:46 ` Kyle McMartin
2006-07-25 22:02 ` Grant Grundler
2006-07-26 21:54 ` James Bottomley
2006-07-25 16:34 ` Thibaut VARENE
2006-07-25 16:37 ` Thibaut VARENE
2006-07-24 14:58 ` John David Anglin
[not found] ` <1153711459.1235.13.camel@mulgrave.il.steeleye.com>
2006-07-24 4:26 ` Thibaut VARENE
2006-07-24 4:31 ` Thibaut VARENE
2006-07-24 14:51 ` James Bottomley
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