From: James Bottomley <James.Bottomley@SteelEye.com>
To: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: PARISC list <parisc-linux@lists.parisc-linux.org>
Subject: Re: [parisc-linux] Proposal for implementing IRQ affinity
Date: 31 Aug 2004 13:29:32 -0400 [thread overview]
Message-ID: <1093973378.3642.5.camel@mulgrave> (raw)
In-Reply-To: <200408310913.47637.bjorn.helgaas@hp.com>
On Tue, 2004-08-31 at 11:13, Bjorn Helgaas wrote:
> You could support 32 (or 64) interrupts per processor if you wanted to,
> though I think right now it's only 32 or 64 for the whole system.
Yes, but in order to do the affinity thing, we have to make it appear as
if a single interrupt vector potentially belongs to all CPUs...
> Strictly speaking, iosapics are programmed with a 16-bit ID/EID (not
> an actual EIRR address) and an 8-bit vector (not a 5- or 6-bit bit
> number.) I think the chipset is responsible for routing the ID/EID
> to the correct processor, and on parisc, probably only 32 (or 64) of
> the 256 possible vectors are usable. I would guess that in addition
> to routing based on ID/EID, the chipset also translates the vector
> number to a 2^vector mask in the form the EIRR expects.
Yes, I'm sorry, sloppy terminology. I don't actually have any iosapic
based machines, so I only had to muck with the iosapic once getting an
a500 SMP working...I was going from memory instead of actually looking
in the code.
> I think it would be good if parisc adopted the more generic concepts,
> because it's a shame that ia64 and parisc have such totally different
> code to drive the identical iosapic hardware.
I agree.
James
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next prev parent reply other threads:[~2004-08-31 17:29 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-31 3:31 [parisc-linux] Proposal for implementing IRQ affinity James Bottomley
2004-08-31 15:13 ` Bjorn Helgaas
2004-08-31 17:29 ` James Bottomley [this message]
2004-08-31 17:43 ` Bjorn Helgaas
2004-08-31 17:14 ` Grant Grundler
2004-08-31 17:43 ` Matthew Wilcox
2004-08-31 18:06 ` Grant Grundler
[not found] ` <20040831185750.GS16196@parcelfarce.linux.theplanet.co.uk>
2004-08-31 19:21 ` Grant Grundler
2004-08-31 19:28 ` Matthew Wilcox
2004-08-31 19:48 ` Grant Grundler
2004-08-31 21:26 ` Michael S. Zick
2004-08-31 22:19 ` Matthew Wilcox
2004-08-31 17:49 ` James Bottomley
2004-08-31 18:34 ` Grant Grundler
2004-08-31 19:44 ` James Bottomley
2004-08-31 20:21 ` Grant Grundler
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