Linux-Block Archive on lore.kernel.org
 help / color / Atom feed
From: Ming Lei <ming.lei@redhat.com>
To: John Garry <john.garry@huawei.com>
Cc: Ming Lei <tom.leiming@gmail.com>, Hannes Reinecke <hare@suse.de>,
	Jens Axboe <axboe@kernel.dk>,
	linux-block <linux-block@vger.kernel.org>,
	Linux SCSI List <linux-scsi@vger.kernel.org>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	Bart Van Assche <bvanassche@acm.org>,
	Hannes Reinecke <hare@suse.com>,
	Don Brace <don.brace@microsemi.com>,
	Kashyap Desai <kashyap.desai@broadcom.com>,
	Sathya Prakash <sathya.prakash@broadcom.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 7/9] scsi: hisi_sas_v3: convert private reply queue to blk-mq hw queue
Date: Tue, 4 Jun 2019 21:37:10 +0800
Message-ID: <20190604133709.GB17248@ming.t460p> (raw)
In-Reply-To: <f1a66b3a-5549-b69d-79fa-7d89b5627a15@huawei.com>

On Mon, Jun 03, 2019 at 02:00:19PM +0100, John Garry wrote:
> On 03/06/2019 12:00, Ming Lei wrote:
> > On Fri, May 31, 2019 at 12:38:10PM +0100, John Garry wrote:
> > > 
> > > > > > -fallback:
> > > > > > -     for_each_possible_cpu(cpu)
> > > > > > -             hisi_hba->reply_map[cpu] = cpu % hisi_hba->queue_count;
> > > > > > -     /* Don't clean all CQ masks */
> > > > > > -}
> > > > > > -
> > > > > >  static int interrupt_init_v3_hw(struct hisi_hba *hisi_hba)
> > > > > >  {
> > > > > >       struct device *dev = hisi_hba->dev;
> > > > > > @@ -2383,11 +2359,6 @@ static int interrupt_init_v3_hw(struct hisi_hba *hisi_hba)
> > > > > > 
> > > > > >               min_msi = MIN_AFFINE_VECTORS_V3_HW;
> > > > > > 
> > > > > > -             hisi_hba->reply_map = devm_kcalloc(dev, nr_cpu_ids,
> > > > > > -                                                sizeof(unsigned int),
> > > > > > -                                                GFP_KERNEL);
> > > > > > -             if (!hisi_hba->reply_map)
> > > > > > -                     return -ENOMEM;
> > > > > >               vectors = pci_alloc_irq_vectors_affinity(hisi_hba->pci_dev,
> > > > > >                                                        min_msi, max_msi,
> > > > > >                                                        PCI_IRQ_MSI |
> > > > > > @@ -2395,7 +2366,6 @@ static int interrupt_init_v3_hw(struct hisi_hba *hisi_hba)
> > > > > >                                                        &desc);
> > > > > >               if (vectors < 0)
> > > > > >                       return -ENOENT;
> > > > > > -             setup_reply_map_v3_hw(hisi_hba, vectors - BASE_VECTORS_V3_HW);
> > > > > >       } else {
> > > > > >               min_msi = max_msi;
> > > > > >               vectors = pci_alloc_irq_vectors(hisi_hba->pci_dev, min_msi,
> > > > > > @@ -2896,6 +2866,18 @@ static void debugfs_snapshot_restore_v3_hw(struct hisi_hba *hisi_hba)
> > > > > >       clear_bit(HISI_SAS_REJECT_CMD_BIT, &hisi_hba->flags);
> > > > > >  }
> > > > > > 
> > > > > > +static int hisi_sas_map_queues(struct Scsi_Host *shost)
> > > > > > +{
> > > > > > +     struct hisi_hba *hisi_hba = shost_priv(shost);
> > > > > > +     struct blk_mq_queue_map *qmap = &shost->tag_set.map[HCTX_TYPE_DEFAULT];
> > > > > > +
> > > > > > +     if (auto_affine_msi_experimental)
> > > > > > +             return blk_mq_pci_map_queues(qmap, hisi_hba->pci_dev,
> > > > > > +                             BASE_VECTORS_V3_HW);
> > > > > > +     else
> > > > > > +             return blk_mq_map_queues(qmap);
> > > 
> > > I don't think that the mapping which blk_mq_map_queues() creates are not
> > > want we want. I'm guessing that we still would like a mapping similar to
> > > what blk_mq_pci_map_queues() produces, which is an even spread, putting
> > > adjacent CPUs on the same queue.
> > > 
> > > For my system with 96 cpus and 16 queues, blk_mq_map_queues() would map
> > > queue 0 to cpu 0, 16, 32, 48 ..., queue 1 to cpu 1, 17, 33 and so on.
> > 
> 
> Hi Ming,
> 
> > blk_mq_map_queues() is the default or fallback mapping in case that managed
> > irq isn't used. If the mapping isn't good enough, we still can improve it
> > in future, then any driver applying it can got improved.
> > 
> 
> That's the right attitude. However, as I see, we can only know the mapping
> when we know the interrupt affinity or some other mapping restriction or
> rule etc, which we don't know in this case.
> 
> For now, personally I would rather if we only expose multiple queues for
> when auto_affine_msi_experimental is set. I fear that we may make a
> performance regression for !auto_affine_msi_experimental with this patch. We
> would need to test.

I suggest to use the blk-mq generic helper.

The default queue mapping of blk_mq_map_queues() has been used for a
while, so far so good, such as, very similar way is applied on
megaraid_sas and mpt3sas, see _base_assign_reply_queues() and
megasas_setup_reply_map().

If performance drop is caused, just report it out, we could fix it.
Or even you can write a new .map_queues method just for hisi_sas v3.


Thanks,
Ming

  reply index

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-31  2:27 [PATCH 0/9] blk-mq/scsi: convert private reply queue into blk_mq " Ming Lei
2019-05-31  2:27 ` [PATCH 1/9] blk-mq: allow hw queues to share hostwide tags Ming Lei
2019-05-31  6:07   ` Hannes Reinecke
2019-05-31 15:37   ` Bart Van Assche
2019-06-24  8:44     ` Ming Lei
2019-06-05 14:10   ` John Garry
2019-06-24  8:46     ` Ming Lei
2019-06-24 13:14       ` John Garry
2019-05-31  2:27 ` [PATCH 2/9] block: null_blk: introduce module parameter of 'g_host_tags' Ming Lei
2019-05-31  6:08   ` Hannes Reinecke
2019-05-31 15:39   ` Bart Van Assche
2019-06-24  8:43     ` Ming Lei
2019-06-02  1:56   ` Minwoo Im
2019-05-31  2:27 ` [PATCH 3/9] scsi: Add template flag 'host_tagset' Ming Lei
2019-05-31  6:08   ` Hannes Reinecke
2019-05-31  2:27 ` [PATCH 4/9] scsi_debug: support host tagset Ming Lei
2019-05-31  6:09   ` Hannes Reinecke
2019-06-02  2:03   ` Minwoo Im
2019-06-02 17:01   ` Douglas Gilbert
2019-05-31  2:27 ` [PATCH 5/9] scsi: introduce scsi_cmnd_hctx_index() Ming Lei
2019-05-31  6:10   ` Hannes Reinecke
2019-05-31  2:27 ` [PATCH 6/9] scsi: hpsa: convert private reply queue to blk-mq hw queue Ming Lei
2019-05-31  6:15   ` Hannes Reinecke
2019-05-31  6:30     ` Ming Lei
2019-05-31  6:40       ` Hannes Reinecke
2019-05-31  2:27 ` [PATCH 7/9] scsi: hisi_sas_v3: " Ming Lei
2019-05-31  6:20   ` Hannes Reinecke
2019-05-31  6:34     ` Ming Lei
2019-05-31  6:42       ` Hannes Reinecke
2019-05-31  7:14         ` Ming Lei
2019-05-31 11:38       ` John Garry
2019-06-03 11:00         ` Ming Lei
2019-06-03 13:00           ` John Garry
2019-06-04 13:37             ` Ming Lei [this message]
2019-05-31  2:28 ` [PATCH 8/9] scsi: megaraid: " Ming Lei
2019-05-31  6:22   ` Hannes Reinecke
2019-06-01 21:41   ` Kashyap Desai
2019-06-02  6:42     ` Ming Lei
2019-06-02  7:48       ` Ming Lei
2019-06-02 16:34         ` Kashyap Desai
2019-06-03  3:56           ` Ming Lei
2019-06-03 10:00             ` Kashyap Desai
2019-06-07  9:45             ` Kashyap Desai
2019-05-31  2:28 ` [PATCH 9/9] scsi: mp3sas: " Ming Lei
2019-05-31  6:23   ` Hannes Reinecke
2019-06-06 11:58   ` Sreekanth Reddy
2019-06-04  8:49 ` [PATCH 0/9] blk-mq/scsi: convert private reply queue into blk_mq " John Garry
2019-08-13  8:30   ` John Garry

Reply instructions:

You may reply publically 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=20190604133709.GB17248@ming.t460p \
    --to=ming.lei@redhat.com \
    --cc=James.Bottomley@hansenpartnership.com \
    --cc=axboe@kernel.dk \
    --cc=bvanassche@acm.org \
    --cc=don.brace@microsemi.com \
    --cc=hare@suse.com \
    --cc=hare@suse.de \
    --cc=hch@lst.de \
    --cc=john.garry@huawei.com \
    --cc=kashyap.desai@broadcom.com \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-scsi@vger.kernel.org \
    --cc=martin.petersen@oracle.com \
    --cc=sathya.prakash@broadcom.com \
    --cc=tom.leiming@gmail.com \
    /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

Linux-Block Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-block/0 linux-block/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-block linux-block/ https://lore.kernel.org/linux-block \
		linux-block@vger.kernel.org
	public-inbox-index linux-block

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-block


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git