24 Jul
2023
24 Jul
'23
3:48 p.m.
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@natalenko.name
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