On 10/29/25 6:46 PM, Allison Henderson wrote:

From: Allison Henderson <redacted>

RDS was written to require ordered workqueues for "cp->cp_wq":
Work is executed in the order scheduled, one item at a time.

If these workqueues are shared across connections,
then work executed on behalf of one connection blocks work
scheduled for a different and unrelated connection.

Luckily we don't need to share these workqueues.
While it obviously makes sense to limit the number of
workers (processes) that ought to be allocated on a system,
a workqueue that doesn't have a rescue worker attached,
has a tiny footprint compared to the connection as a whole:
A workqueue costs ~800 bytes, while an RDS/IB connection
totals ~5 MBytes.

Still a workqueue per connection feels overkill. Have you considered
moving to WQ_PERCPU for rds_wq? Why does not fit?

Thanks,

Paolo