linux-kernel - Re: automatic interrupt affinity for MSI/MSI-X capable devices V2

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Message-ID: <b8cdfc80-fa77-b7cc-69b8-fb6037114087@sandisk.com>
Date:	Thu, 16 Jun 2016 11:45:55 +0200
From:	Bart Van Assche <bart.vanassche@...disk.com>
To:	Christoph Hellwig <hch@....de>, <tglx@...utronix.de>,
	<axboe@...com>
CC:	<linux-block@...r.kernel.org>, <linux-pci@...r.kernel.org>,
	<linux-nvme@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: automatic interrupt affinity for MSI/MSI-X capable devices V2

On 06/14/2016 09:58 PM, Christoph Hellwig wrote:
> This series enhances the irq and PCI code to allow spreading around MSI and
> MSI-X vectors so that they have per-cpu affinity if possible, or at least
> per-node.  For that it takes the algorithm from blk-mq, moves it to
> a common place, and makes it available through a vastly simplified PCI
> interrupt allocation API.  It then switches blk-mq to be able to pick up
> the queue mapping from the device if available, and demonstrates all this
> using the NVMe driver.

Hello Christoph,

Is my interpretation correct that for an adapter that supports two 
interrupts and on a system with eight CPU cores and no hyperthreading 
this patch series will assign interrupt vector 0 to CPU 0 and interrupt 
vector 1 to CPU 1? Are you aware that drivers like ib_srp assume that 
interrupts have been spread evenly, that means assigning vector 0 to CPU 
0 and vector 1 to CPU 4?

Thanks,

Bart.