I have an 8-port SATA disk controller in a PCIe slot (thanks, Trevor!), and it seems to be sharing an interrupt. I'm running Ubuntu Server 9.10 64-bit. Is there some way to arrange for it to have its own interrupt, unshared?
Kevin
Short answer: no.
Sharing interrupts in PCIe is a normal state of affairs. You’d have to have a BIOS that allowed you to override that.
On the upside, the historical case of sharing interrupts being bad, both because of drivers that didn’t allow for that and because of the performance hit, is just that – historical. There is a theoretically measurable performance hit even under PCIe, but it’s negligibly small. (Or at least it’s supposed to be. Bad drivers can screw anything up.)
Why do you want it to have its own interrupt?
-Adam Thompson
(204) 291-7950
From: roundtable-bounces@muug.mb.ca [mailto:roundtable-bounces@muug.mb.ca] On Behalf Of Kevin McGregor Sent: Monday, April 05, 2010 17:36 To: MUUG Roundtable Subject: [RndTbl] PCIe interrupt assignments
I have an 8-port SATA disk controller in a PCIe slot (thanks, Trevor!), and it seems to be sharing an interrupt. I'm running Ubuntu Server 9.10 64-bit. Is there some way to arrange for it to have its own interrupt, unshared?
Kevin
Oh, it was just suggested by a (presumably very outdated) RAID article I found. I didn't think it would be a big deal for the reasons you mentioned. Plus it's sharing the interrupt with two USB ports which don't even have the motherboard adapter connected to them.
Thanks for the confirmation.
On Mon, Apr 5, 2010 at 5:39 PM, Adam Thompson athompso@athompso.net wrote:
On 2010-04-05 Kevin McGregor wrote:
a) You can possibly disable those unused usb ports, some mobo bios's allow you to somewhat granularly disable groups of ports.
b) Try changing the mobo BIOS from "PNP aware OS" enabled to disabled or vice-versa. That changes who sets the IRQ's, OS or BIOS. If your board has that option... Of course, it's still the luck of the draw in either case whether IRQs get shared. My take on it is these days you just don't worry about it anymore.
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Adam Thompson -
Kevin McGregor -
Trevor Cordes