From: "jianchao.wang" <jianchao.w.wang@oracle.com>
To: Keith Busch <keith.busch@intel.com>
Cc: axboe@fb.com, linux-kernel@vger.kernel.org, hch@lst.de,
linux-nvme@lists.infradead.org, sagi@grimberg.me
Subject: Re: [PATCH] nvme-pci: assign separate irq vectors for adminq and ioq0
Date: Wed, 28 Feb 2018 10:53:31 +0800 [thread overview]
Message-ID: <9252f0a1-f3e5-414b-db49-e8053dfa48a6@oracle.com> (raw)
In-Reply-To: <20180227151311.GD10832@localhost.localdomain>
Hi Keith
Thanks for your precious time to review this.
On 02/27/2018 11:13 PM, Keith Busch wrote:
> On Tue, Feb 27, 2018 at 04:46:17PM +0800, Jianchao Wang wrote:
>> Currently, adminq and ioq0 share the same irq vector. This is
>> unfair for both amdinq and ioq0.
>> - For adminq, its completion irq has to be bound on cpu0.
>> - For ioq0, when the irq fires for io completion, the adminq irq
>> action has to be checked also.
>
> This change log could use some improvements. Why is it bad if admin
> interrupts affinity is with cpu0?
adminq interrupts should be able to fire everywhere.
do we have any reason to bound it on cpu0 ?
>
> Are you able to measure _any_ performance difference on IO queue 1 vs IO
> queue 2 that you can attribute to IO queue 1's sharing vector 0?
Actually, I didn't get any performance improving on my own NVMe card.
But it may be needed on some enterprise card, especially the media is persist memory.
nvme_irq will be invoked twice when ioq0 irq fires, this will introduce another unnecessary DMA
accessing on cq entry.
>
>> @@ -1945,11 +1947,11 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
>> * setting up the full range we need.
>> */
>> pci_free_irq_vectors(pdev);
>> - nr_io_queues = pci_alloc_irq_vectors(pdev, 1, nr_io_queues,
>> - PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY);
>> - if (nr_io_queues <= 0)
>> + ret = pci_alloc_irq_vectors_affinity(pdev, 1, (nr_io_queues + 1),
>> + PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd);
>> + if (ret <= 0)
>> return -EIO;
>> - dev->max_qid = nr_io_queues;
>> + dev->max_qid = ret - 1;
>
> So controllers that have only legacy or single-message MSI don't get any
> IO queues?
>
Yes. At the moment, we have to share the only one irq vector.
Thanks for your directive. :)
Jianchao
next prev parent reply other threads:[~2018-02-28 2:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-27 8:46 [PATCH] nvme-pci: assign separate irq vectors for adminq and ioq0 Jianchao Wang
2018-02-27 15:13 ` Keith Busch
2018-02-28 2:53 ` jianchao.wang [this message]
2018-02-28 15:27 ` Keith Busch
2018-02-28 15:42 ` jianchao.wang
2018-02-28 15:46 ` jianchao.wang
2018-02-28 15:53 ` Keith Busch
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9252f0a1-f3e5-414b-db49-e8053dfa48a6@oracle.com \
--to=jianchao.w.wang@oracle.com \
--cc=axboe@fb.com \
--cc=hch@lst.de \
--cc=keith.busch@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nvme@lists.infradead.org \
--cc=sagi@grimberg.me \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).