linux-kernel - [PATCH v3 13/15] virtio: blk/scsi: use block layer helpers to calculate num of queues

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Message-Id: <20240806-isolcpus-io-queues-v3-13-da0eecfeaf8b@suse.de>
Date: Tue, 06 Aug 2024 14:06:45 +0200
From: Daniel Wagner <dwagner@...e.de>
To: Jens Axboe <axboe@...nel.dk>, Keith Busch <kbusch@...nel.org>, 
 Sagi Grimberg <sagi@...mberg.me>, Thomas Gleixner <tglx@...utronix.de>, 
 Christoph Hellwig <hch@....de>, 
 "Martin K. Petersen" <martin.petersen@...cle.com>, 
 John Garry <john.g.garry@...cle.com>, "Michael S. Tsirkin" <mst@...hat.com>, 
 Jason Wang <jasowang@...hat.com>, 
 Kashyap Desai <kashyap.desai@...adcom.com>, 
 Sumit Saxena <sumit.saxena@...adcom.com>, 
 Shivasharan S <shivasharan.srikanteshwara@...adcom.com>, 
 Chandrakanth patil <chandrakanth.patil@...adcom.com>, 
 Sathya Prakash Veerichetty <sathya.prakash@...adcom.com>, 
 Suganath Prabu Subramani <suganath-prabu.subramani@...adcom.com>, 
 Nilesh Javali <njavali@...vell.com>, GR-QLogic-Storage-Upstream@...vell.com, 
 Jonathan Corbet <corbet@....net>
Cc: Frederic Weisbecker <frederic@...nel.org>, Mel Gorman <mgorman@...e.de>, 
 Hannes Reinecke <hare@...e.de>, 
 Sridhar Balaraman <sbalaraman@...allelwireless.com>, 
 "brookxu.cn" <brookxu.cn@...il.com>, Ming Lei <ming.lei@...hat.com>, 
 linux-kernel@...r.kernel.org, linux-block@...r.kernel.org, 
 linux-nvme@...ts.infradead.org, linux-scsi@...r.kernel.org, 
 virtualization@...ts.linux.dev, megaraidlinux.pdl@...adcom.com, 
 mpi3mr-linuxdrv.pdl@...adcom.com, MPT-FusionLinux.pdl@...adcom.com, 
 storagedev@...rochip.com, linux-doc@...r.kernel.org, 
 Daniel Wagner <dwagner@...e.de>
Subject: [PATCH v3 13/15] virtio: blk/scsi: use block layer helpers to
 calculate num of queues

Multiqueue devices should only allocate queues for the housekeeping CPUs
when isolcpus=io_queue is set. This avoids that the isolated CPUs get
disturbed with OS workload.

Use helpers which calculates the correct number of queues which should
be used when isolcpus is used.

Signed-off-by: Daniel Wagner <dwagner@...e.de>
---
 drivers/block/virtio_blk.c | 5 ++---
 drivers/scsi/virtio_scsi.c | 1 +
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 8f68037da00b..3584a1e00791 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -982,9 +982,8 @@ static int init_vq(struct virtio_blk *vblk)
 		return -EINVAL;
 	}

-	num_vqs = min_t(unsigned int,
-			min_not_zero(num_request_queues, nr_cpu_ids),
-			num_vqs);
+	num_vqs = blk_mq_num_possible_queues(
+			min_not_zero(num_request_queues, num_vqs));

 	num_poll_vqs = min_t(unsigned int, poll_queues, num_vqs - 1);

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 8013a082598b..1c1feec59781 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -921,6 +921,7 @@ static int virtscsi_probe(struct virtio_device *vdev)
 	/* We need to know how many queues before we allocate. */
 	num_queues = virtscsi_config_get(vdev, num_queues) ? : 1;
 	num_queues = min_t(unsigned int, nr_cpu_ids, num_queues);
+	num_queues = blk_mq_num_possible_queues(num_queues);

 	num_targets = virtscsi_config_get(vdev, max_target) + 1;

-- 
2.46.0