Re: [PATCH] x86/mm: Tracking linear mapping split events since boot

Tejun Heo
2021-01-26T10:42:58Z

Hello, Dave.

On Mon, Jan 25, 2021 at 04:47:42PM -0800, Dave Hansen wrote:
> The patch here does not actually separate out pre-boot from post-boot,
> so it's pretty hard to tell if the splits came from something like
> tracing which is totally unnecessary or they were the result of
> something at boot that we can't do anything about.

Ah, right, didn't know they also included splits during boot. It'd be a lot
more useful if they were counting post-boot splits.

> This would be a lot more useful if you could reset the counters. Then
> just reset them from userspace at boot. Adding read-write debugfs
> exports for these should be pretty trivial.

While this would work for hands-on cases, I'm a bit worried that this might
be more challenging to gain confidence in large production environments.

Thanks.

--
tejun