On 2021-07-08 15:36, Doug Anderson wrote:
[...]
Or document for the users that want performance how to
change the setting, so that they can decide.
Pushing this to the users can make sense for a Linux distribution but
probably less sense for an embedded platform. So I'm happy to make
some way for a user to override this (like via kernel command line),
but I also strongly believe there should be a default that users don't
have to futz with that we think is correct.
FYI I did make progress on the "punt it to userspace" approach. I'm not
posting it even as an RFC yet because I still need to set up a machine
to try actually testing any of it (it's almost certainly broken
somewhere), but in the end it comes out looking surprisingly not too bad
overall. If you're curious to take a look in the meantime I put it here:
https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/fq
Cheers,
Robin.
