[Powertop] Intel GPU statistics on multi-GPU systems

[Niels Penneman <niels at penneman.org>]

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Hi all,

Currently powertop tries to find Intel GPU statistics in sysfs with a
hardcoded path; in src/cpu/cpu.cpp:353-354:

if (access("/sys/class/drm/card0/power/rc6_residency_ms", R_OK) == 0)
 handle_i965_gpu();

In systems with multiple GPUs it is not guaranteed that the Intel GPU is
labeled 'card0' in sysfs. In my system with both integrated Intel and
discrete AMD Radeon the Intel GPU is 'card1', and powertop will not
display GPU statistics.

One possible solution would be to scan all /sys/class/drm/card[0-9]+
folders and check the vendor & device IDs in 'device/vendor' and
'device/device'. Perhaps there is a better solution, e.g. by examining
the PCI device tree.


Regards,

-- 
Niels Penneman
Computer Systems Lab
Electronics and Information Systems Department
Ghent University


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