From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Christoph Hellwig <hch@lst.de>
Cc: linuxppc-dev@ozlabs.org, Michael Neuling <mikey@neuling.org>,
paulus@samba.org, anton@samba.org, sfr@canb.auug.org.au
Subject: Re: [PATCH] SLB shadow buffer
Date: Wed, 09 Aug 2006 13:22:59 +0200 [thread overview]
Message-ID: <1155122580.4040.96.camel@localhost.localdomain> (raw)
In-Reply-To: <20060805124544.GB23494@lst.de>
On Sat, 2006-08-05 at 14:45 +0200, Christoph Hellwig wrote:
> On Fri, Aug 04, 2006 at 03:53:19PM +1000, Michael Neuling wrote:
> > This adds a shadow buffer for the SLBs and regsiters it with PHYP.
> > Only the bolted SLB entries (first 3) are saved.
>
> What is a SLB shadow buffer and why do we need it? (I don't want to
> question the patch but rather learn a little more about lowlevel ppc64
> mmu details)
Yeah, same question :) I don't have my PAPR at hand and I'm still
travellling but I'm curious about that one...
I would suspect it allows the HV to save/restore SLBs when sharing a
processor between partitions but then... the kernel requires that anyway
so either the current code is bogus and that's pretty bad (which I don't
think so) or maybe the fact that we didn't register the shadow caused HV
to always save/restore the entire SLB, while by using the shadow, we let
it save/restore only the bolted entries we put in there (and just
re-fault the other ones). If it's not that, then what ? :)
Ben.
next prev parent reply other threads:[~2006-08-09 12:35 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-04 5:53 [PATCH] SLB shadow buffer Michael Neuling
2006-08-05 12:45 ` Christoph Hellwig
2006-08-09 11:22 ` Benjamin Herrenschmidt [this message]
2006-08-09 13:01 ` Segher Boessenkool
-- strict thread matches above, loose matches on Subject: below --
2006-08-05 5:56 Milton Miller
2006-08-07 5:55 ` Michael Neuling
2006-08-05 21:18 Milton Miller
2006-08-06 1:27 ` Michael Neuling
2006-08-07 6:19 Michael Neuling
2006-08-08 1:15 Milton Miller
2006-08-08 4:21 ` Michael Neuling
2006-08-08 4:29 Michael Neuling
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