[PATCH v6 3/9] nvme-pci: use block layer helpers to calculate num of queues

Daniel Wagner dwagner at suse.de
Wed May 14 09:12:04 PDT 2025


On Fri, May 09, 2025 at 09:47:31AM +0800, Ming Lei wrote:
> On Thu, Apr 24, 2025 at 08:19:42PM +0200, Daniel Wagner wrote:
> > 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.
> 
> The commit log needs to be updated:
> 
> - io_queue isn't introduced yet
> 
> - this patch can only reduce nr_hw_queues, and queue mapping isn't changed
> yet, so nothing to do with
> 
>  "This avoids that the isolated CPUs get disturbed with OS workload"

What about:

  The calculation of the upper limit for queues does not depend solely on
  the number of possible CPUs; for example, the isolcpus kernel
  command-line option must also be considered.

  To account for this, the block layer provides a helper function to
  retrieve the maximum number of queues. Use it to set an appropriate
  upper queue number limit.

I would use this version for the other patches as well,
s/possible/online/ where necessary.



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