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

[Greg KH]

On Mon, Jul 24, 2023 at 04:35:43PM +0100, Phil Elwell wrote:
> 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.

This has been discussed already:
	https://lore.kernel.org/r/12251678.O9o76ZdvQC@xxxxxxxxxxxxxx

It's not a bug, mariadb does have pending I/O, so the report is correct,
but the CPU isn't blocked at all.

thanks,

greg k-h