Re: [PATCH v5 8/9] blk-mq: issue warning when offlining hctx with online isolcpus

[Hannes Reinecke]

On 1/10/25 17:26, Daniel Wagner wrote:
> When isolcpus=managed_irq is enabled, and the last housekeeping CPU for
> a given hardware context goes offline, there is no CPU left which
> handles the IOs anymore. If isolated CPUs mapped to this hardware
> context are online and an application running on these isolated CPUs
> issue an IO this will lead to stalls.
>
> The kernel will not schedule IO to isolated CPUS thus this avoids IO
> stalls.
>
> Thus issue a warning when housekeeping CPUs are offlined for a hardware
> context while there are still isolated CPUs online.
>
> Signed-off-by: Daniel Wagner <wagi@xxxxxxxxxx>
> ---
>   block/blk-mq.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 42 insertions(+), 1 deletion(-)
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>

Cheers,

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