From: Grant Grundler <grundler@parisc-linux.org>
To: "Michael S. Zick" <mszick@morethan.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>,
John David Anglin <dave@hiauly1.hia.nrc.ca>,
parisc-linux@lists.parisc-linux.org
Subject: Re: [parisc-linux] Heavy Iron Reference Docs
Date: Tue, 2 May 2006 00:24:42 -0600 [thread overview]
Message-ID: <20060502062442.GC14414@colo.lackof.org> (raw)
In-Reply-To: <200604301828.26318.mszick@morethan.org>
On Sun, Apr 30, 2006 at 06:28:26PM -0500, Michael S. Zick wrote:
> On Sun April 30 2006 18:01, Michael S. Zick wrote:
> >
> > Scratches head...
> >
> > I wonder where Joel has his processors installed in relation to the
> > two busses? Both on same buss or one per buss? Would his lockups
> > go away if he picked the other relationship?
> >
> > I will ask him. (or perhaps I just did)
> >
>
> Browsing old parisc spinlock code, I find a comment that the N4K
> can only have one outstanding PxTLB transaction at a time.
The original document says:
The Merced bus is designed to only support a single broadcast
PxTLB transaction in progress at a time, and this must be guaranteed
by software. Software must semaphore to guarantee that only one
processor is trying to issue a broadcast PxTLB at a time.
Local PxTLBs, however, have no restrictions, since they are executed
entirely on the issuing processor.
> Is it not the PxTLB transactions that implement the inter-processor
> coherency?
I don't think so.
>
> Which is of course required for inter-processor spinlocks to work.
>
> And, of course, this being Linux, the queue is protected by a spinlock!
PA-RISC _only_ has a spinlock.
> Did someone just shoot themselves in the foot?
Do you honestly think the HP HW engineers were _that_ stupid?
They occasionally make mistakes....but designing an SMP machine
that doesn't have at least one working atomic op would be a bit
over the top. ;)
grant
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next prev parent reply other threads:[~2006-05-02 6:24 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-30 3:50 [parisc-linux] Heavy Iron Reference Docs Michael S. Zick
2006-04-30 4:36 ` John David Anglin
2006-04-30 17:13 ` Kyle McMartin
2006-04-30 21:25 ` John David Anglin
2006-04-30 23:01 ` Michael S. Zick
2006-04-30 23:28 ` Michael S. Zick
2006-05-02 6:24 ` Grant Grundler [this message]
2006-05-02 11:27 ` Michael S. Zick
2006-04-30 23:30 ` John David Anglin
2006-05-01 3:23 ` Michael S. Zick
2006-05-02 6:00 ` Grant Grundler
2006-05-02 15:10 ` John David Anglin
2006-05-02 15:13 ` Kyle McMartin
2006-05-02 15:41 ` John David Anglin
2006-04-30 7:03 ` Grant Grundler
2006-04-30 13:12 ` Michael S. Zick
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