Re: [PATCH] swiotlb: eliminate per-map atomic contention on used/hiwater tracking

[Robin Murphy <robin.murphy@arm.com>]

On 2026-06-23 3:35 am, Michael Kelley wrote:
[...]
> Another approach to the contention problem would be to have a separate
> CONFIG option that is narrower than CONFIG_DEBUG_FS, so that the
> computation of the hiwater mark can be dropped entirely in production
> environments. Or the setting could be dynamic at runtime via a
> static_call, defaulting to not computing the hiwater mark while still
> allowing a sysadmin to turn it on to see workload usage of the swiotlb.

Yeah, in terms of usefulness to admins, I'd imagine a sysctl to enable 
stats collection would probably be better than a config option - I doubt 
that most folks who just want to tune a standard distro kernel for their 
VM workload would want to have to rebuild it. A command line option 
might also be a fair compromise if that's how the eventual SWIOTLB 
tuning will be controlled anyway.

Thanks,
Robin.