linux-kernel - Re: [PATCH 1/6] blk-mq: introduce blk_mq_hctx_map

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Message-ID: <0bd0be63-5595-4aae-829f-6b278a5b5e60@kernel.dk>
Date: Sun, 15 Sep 2024 14:32:30 -0600
From: Jens Axboe <axboe@...nel.dk>
To: Bjorn Helgaas <helgaas@...nel.org>, Daniel Wagner <wagi@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, "Michael S. Tsirkin"
 <mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
 "Martin K. Petersen" <martin.petersen@...cle.com>,
 Keith Busch <kbusch@...nel.org>, Christoph Hellwig <hch@....de>,
 Sagi Grimberg <sagi@...mberg.me>, linux-block@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
 virtualization@...ts.linux.dev, linux-scsi@...r.kernel.org,
 megaraidlinux.pdl@...adcom.com, mpi3mr-linuxdrv.pdl@...adcom.com,
 MPT-FusionLinux.pdl@...adcom.com, storagedev@...rochip.com,
 linux-nvme@...ts.infradead.org, Daniel Wagner <dwagner@...e.de>,
 20240912-do-not-overwrite-pci-mapping-v1-1-85724b6cec49@...e.de,
 Ming Lei <ming.lei@...hat.com>
Subject: Re: [PATCH 1/6] blk-mq: introduce blk_mq_hctx_map_queues

On 9/13/24 10:26 AM, Bjorn Helgaas wrote:
> On Fri, Sep 13, 2024 at 09:41:59AM +0200, Daniel Wagner wrote:
>> From: Ming Lei <ming.lei@...hat.com>
>>
>> blk_mq_pci_map_queues and blk_mq_virtio_map_queues will create a CPU to
>> hardware queue mapping based on affinity information. These two
>> function share code which only differs on how the affinity information
>> is retrieved. Also there is the hisi_sas which open codes the same loop.
>>
>> Thus introduce a new helper function for creating these mappings which
>> takes an callback function for fetching the affinity mask. Also
>> introduce common helper function for PCI and virtio devices to retrieve
>> affinity masks.
> 
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index e3a49f66982d..84f9c16b813b 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -6370,6 +6370,26 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
>>  	return 0;
>>  }
>>  
>> +#ifdef CONFIG_BLK_MQ_PCI
>> +/**
>> + * pci_get_blk_mq_affinity - get affinity mask queue mapping for PCI device
>> + * @dev_data:	Pointer to struct pci_dev.
>> + * @offset:	Offset to use for the pci irq vector
>> + * @queue:	Queue index
>> + *
>> + * This function returns for a queue the affinity mask for a PCI device.
>> + * It is usually used as callback for blk_mq_hctx_map_queues().
>> + */
>> +const struct cpumask *pci_get_blk_mq_affinity(void *dev_data, int offset,
>> +					      int queue)
>> +{
>> +	struct pci_dev *pdev = dev_data;
>> +
>> +	return pci_irq_get_affinity(pdev, offset + queue);
>> +}
>> +EXPORT_SYMBOL_GPL(pci_get_blk_mq_affinity);
>> +#endif
> 
> IMO this doesn't really fit well in drivers/pci since it doesn't add
> any PCI-specific knowledge or require any PCI core internals, and the
> parameters are blk-specific.  I don't object to the code, but it seems
> like it could go somewhere in block/?

Probably not a bad idea.

Unrelated to that topic, but Daniel, all your email gets marked as spam.
I didn't see your series before this reply. This has been common
recently for people that haven't kept up with kernel.org changes, please
check for smtp changes there.

-- 
Jens Axboe