Am 02.05.23 um 03:26 schrieb André Almeida:
Em 01/05/2023 16:24, Alex Deucher escreveu:
On Mon, May 1, 2023 at 2:58 PM André Almeida <andrealmeid@xxxxxxxxxx>
wrote:
I know that devcoredump is also used for this kind of information,
but I believe
that using an IOCTL is better for interfacing Mesa + Linux rather
than parsing
a file that its contents are subjected to be changed.
Can you elaborate a bit on that? Isn't the whole point of devcoredump
to store this sort of information?
I think that devcoredump is something that you could use to submit to
a bug report as it is, and then people can read/parse as they want,
not as an interface to be read by Mesa... I'm not sure that it's
something that I would call an API. But I might be wrong, if you know
something that uses that as an API please share.
Anyway, relying on that for Mesa would mean that we would need to
ensure stability for the file content and format, making it less
flexible to modify in the future and probe to bugs, while the IOCTL is
well defined and extensible. Maybe the dump from Mesa + devcoredump
could be complementary information to a bug report.
Neither using an IOCTL nor devcoredump is a good approach for this since
the values read from the hw register are completely unreliable. They
could not be available because of GFXOFF or they could be overwritten or
not even updated by the CP in the first place because of a hang etc....
If you want to track progress inside an IB what you do instead is to
insert intermediate fence write commands into the IB. E.g. something
like write value X to location Y when this executes.
This way you can not only track how far the IB processed, but also in
which stages of processing we where when the hang occurred. E.g. End of
Pipe, End of Shaders, specific shader stages etc...
Regards,
Christian.
