Re: [PATCH v5 7/9] blk-mq: use hk cpus only when isolcpus=managed_irq is enabled

[Hannes Reinecke]

On 1/10/25 17:26, Daniel Wagner wrote:
> When isolcpus=managed_irq is enabled all hardware queues should run on
> the housekeeping CPUs only. Thus ignore the affinity mask provided by
> the driver. Also we can't use blk_mq_map_queues because it will map all
> CPUs to first hctx unless, the CPU is the same as the hctx has the
> affinity set to, e.g. 8 CPUs with isolcpus=managed_irq,2-3,6-7 config
>
>    queue mapping for /dev/nvme0n1
>          hctx0: default 2 3 4 6 7
>          hctx1: default 5
>          hctx2: default 0
>          hctx3: default 1
>
>    PCI name is 00:05.0: nvme0n1
>          irq 57 affinity 0-1 effective 1 is_managed:0 nvme0q0
>          irq 58 affinity 4 effective 4 is_managed:1 nvme0q1
>          irq 59 affinity 5 effective 5 is_managed:1 nvme0q2
>          irq 60 affinity 0 effective 0 is_managed:1 nvme0q3
>          irq 61 affinity 1 effective 1 is_managed:1 nvme0q4
>
> where as with blk_mq_hk_map_queues we get
>
>    queue mapping for /dev/nvme0n1
>          hctx0: default 2 4
>          hctx1: default 3 5
>          hctx2: default 0 6
>          hctx3: default 1 7
>
>    PCI name is 00:05.0: nvme0n1
>          irq 56 affinity 0-1 effective 1 is_managed:0 nvme0q0
>          irq 61 affinity 4 effective 4 is_managed:1 nvme0q1
>          irq 62 affinity 5 effective 5 is_managed:1 nvme0q2
>          irq 63 affinity 0 effective 0 is_managed:1 nvme0q3
>          irq 64 affinity 1 effective 1 is_managed:1 nvme0q4
>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Daniel Wagner <wagi@xxxxxxxxxx>
> ---
>   block/blk-mq-cpumap.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 65 insertions(+)
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>

Cheers,

Hannes
--
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@xxxxxxx                                +49 911 74053 688
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