linux-kernel - Re: [PATCH] nvme: use the correct msix vector for each queue

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Message-ID: <CALZtONCTvpa4ctjN7QJaeKcXi2iEQ2EieqDkQac3wnmKoEyEcA@mail.gmail.com>
Date:   Wed, 7 Dec 2016 17:49:19 -0500
From:   Dan Streetman <ddstreet@...e.org>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Keith Busch <keith.busch@...el.com>, Jens Axboe <axboe@...com>,
        Dan Streetman <dan.streetman@...onical.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-nvme@...ts.infradead.org
Subject: Re: [PATCH] nvme: use the correct msix vector for each queue

On Wed, Dec 7, 2016 at 5:46 PM, Christoph Hellwig <hch@...radead.org> wrote:
> On Wed, Dec 07, 2016 at 05:49:42PM -0500, Keith Busch wrote:
>> I'm just saying that blk-mq's hctx mapping will end up choosing a queue
>> who's vector is mapped to a different CPU, and we don't want that.
>
> Right.  For 4.10 we could use the pci_alloc_irq_vectors_affinity helper
> to set away a pre_vector IFF we want a separate vector for the admin
> queue.
>
>> We are currently sharing the first IO queue's interrupt vector with
>> the admin queue's on purpose. Are you saying there's something wrong
>> with that?
>
> But given that the sharing was done intentionally and we had a long
> discussion on it back then there should be no real reason to change
> the assignment in NVMe.

sorry, i missed the past discussion.  It still seems strange and
obscure that it's intentional, from reading the code at least.