Re: [PATCH] io_uring: Use io_schedule* in cqring wait

[Phil Elwell]

Hi Andres,

With this commit applied to the 6.1 and later kernels (others not
tested) the iowait time ("wa" field in top) in an ARM64 build running
on a 4 core CPU (a Raspberry Pi 4 B) increases to 25%, as if one core
is permanently blocked on I/O. The change can be observed after
installing mariadb-server (no configuration or use is required). After
reverting just this commit, "wa" drops to zero again.

I can believe that this change hasn't negatively affected performance,
but the result is misleading. I also think it's pushing the boundaries
of what a back-port to stable should do.

Phil