On Wed, May 07 2025 at 17:04, Zijiang Huang wrote:
> I think it's safe to make this change for user-space accessors as well,
> since user-space only reads from proc files.
Again. See pci_cfg_access_lock()
>> Why is performance of the user space accessors important?
>> Perhaps because of vfio?
>
> During stability testing on large-scale machines (384+ CPUs), we always > observed that heavy concurrent user-space access to PCI config space triggers
> kernel softlockups.
>
> Reproduction method: stress-ng --pci 384
This is not really interesting as stress-ng is not a real world work
load.
What's the actual real world use case which uses those interfaces so
that the lock becomes an issue?
Thanks,
tglx
