linux-kernel - Re: [PATCH v4 6/9] virtio: blk/scsi: use block layer helpers to calculate num of queues

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Message-ID: <20241219032956-mutt-send-email-mst@kernel.org>
Date: Thu, 19 Dec 2024 03:31:05 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Daniel Wagner <wagi@...nel.org>
Cc: Jens Axboe <axboe@...nel.dk>, Keith Busch <kbusch@...nel.org>,
	Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
	Kashyap Desai <kashyap.desai@...adcom.com>,
	Sumit Saxena <sumit.saxena@...adcom.com>,
	Shivasharan S <shivasharan.srikanteshwara@...adcom.com>,
	Chandrakanth patil <chandrakanth.patil@...adcom.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	Nilesh Javali <njavali@...vell.com>,
	GR-QLogic-Storage-Upstream@...vell.com,
	Don Brace <don.brace@...rochip.com>,
	Jason Wang <jasowang@...hat.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Stefan Hajnoczi <stefanha@...hat.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Costa Shulyupin <costa.shul@...hat.com>,
	Juri Lelli <juri.lelli@...hat.com>,
	Valentin Schneider <vschneid@...hat.com>,
	Waiman Long <llong@...hat.com>, Ming Lei <ming.lei@...hat.com>,
	Michal Koutný <mkoutny@...e.com>,
	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>, linux-kernel@...r.kernel.org,
	linux-block@...r.kernel.org, linux-nvme@...ts.infradead.org,
	megaraidlinux.pdl@...adcom.com, linux-scsi@...r.kernel.org,
	storagedev@...rochip.com, virtualization@...ts.linux.dev
Subject: Re: [PATCH v4 6/9] virtio: blk/scsi: use block layer helpers to
 calculate num of queues

On Tue, Dec 17, 2024 at 07:29:40PM +0100, Daniel Wagner wrote:
> Multiqueue devices should only allocate queues for the housekeeping CPUs
> when isolcpus=managed_irq 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 <wagi@...nel.org>

The subject is misleading, one thinks it is onlu virtio blk.
It's best to just split each driver in a patch by its own.
for the changes in virtio:

Acked-by: Michael S. Tsirkin <mst@...hat.com>

> ---
>  drivers/block/virtio_blk.c                | 5 ++---
>  drivers/scsi/megaraid/megaraid_sas_base.c | 3 ++-
>  drivers/scsi/virtio_scsi.c                | 1 +
>  3 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index ed514ff46dc82acd629ae594cb0fa097bd301a9b..0287ceaaf19972f3a18e81cd2e3252e4d539ba93 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -976,9 +976,8 @@ 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/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
> index 59d385e5a917979ae2f61f5db2c3355b9cab7e08..3ff0978b3acb5baf757fee25d9fccf4971976272 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_base.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
> @@ -6236,7 +6236,8 @@ static int megasas_init_fw(struct megasas_instance *instance)
>  		intr_coalescing = (scratch_pad_1 & MR_INTR_COALESCING_SUPPORT_OFFSET) ?
>  								true : false;
>  		if (intr_coalescing &&
> -			(blk_mq_num_online_queues(0) >= MR_HIGH_IOPS_QUEUE_COUNT) &&
> +			(blk_mq_num_online_queues(0) >=
> +			 MR_HIGH_IOPS_QUEUE_COUNT) &&
>  			(instance->msix_vectors == MEGASAS_MAX_MSIX_QUEUES))
>  			instance->perf_mode = MR_BALANCED_PERF_MODE;
>  		else
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 60be1a0c61836ba643adcf9ad8d5b68563a86cb1..46ca0b82f57ce2211c7e2817dd40ee34e65bcbf9 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -919,6 +919,7 @@ 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;
>  
> 
> -- 
> 2.47.1