On 9/29/2022 3:37 PM, Lazar, Lijo wrote:
To be clear your understanding -
Nothing is automatic in PMFW. PMFW picks a priority based on the actual
mask sent by driver.
Assuming lower bits corresponds to highest priority -
If driver sends a mask with Bit3 and Bit 0 set, PMFW will chose profile
that corresponds to Bit0. If driver sends a mask with Bit4 Bit2 set and
rest unset, PMFW will chose profile that corresponds to Bit2. However if
driver sends a mask only with a single bit set, it chooses the profile
regardless of whatever was the previous profile. t doesn't check if the
existing profile > newly requested one. That is the behavior.
So if a job send chooses a profile that corresponds to Bit0, driver will
send that. Next time if another job chooses a profile that corresponds
to Bit1, PMFW will receive that as the new profile and switch to that.
It trusts the driver to send the proper workload mask.
Hope that gives the picture.
Thanks, my understanding is also similar, referring to the core power
switch profile function here: amd_powerplay.c::pp_dpm_switch_power_profile()
*snip code*
hwmgr->workload_mask |= (1 << hwmgr->workload_prority[type]);
index = fls(hwmgr->workload_mask);
index = index <= Workload_Policy_Max ? index - 1 : 0;
workload = hwmgr->workload_setting[index];
*snip_code*
hwmgr->hwmgr_func->set_power_profile_mode(hwmgr, &workload, 0);
Here I can see that the new workload mask is appended into the existing
workload mask (not overwritten). So if we keep sending new
workload_modes, they would be appended into the workload flags and
finally the PM will pick the most aggressive one of all these flags, as
per its policy.
Now, when we have a single workload:
-> Job1: requests profile P1 via UAPI, ref count = 1
-> driver sends flags for p1
-> PM FW applies profile P1
-> Job executes in profile P1
-> Job goes to reset function, ref_count = 0,
-> Power profile resets
Now, we have conflicts only when we see multiple workloads (Job1 and Job 2)
-> Job1: requests profile P1 via UAPI, ref count = 1
-> driver sends flags for p1
-> PM FW applies profile P1
-> Job executes in profile P1
-> Job2: requests profile P2 via UAPI, refcount = 2
-> driver sends flags for (P1|P2)
-> PM FW picks the more aggressive of the two (Say P1, stays in P1)
-> Job1 goes to reset function, ref_count = 1, job1 does not reset power
profile
-> Job2 goes to reset function, ref_counter = 2, job 2 resets Power profile
-> Power profile resets to None
So this state machine looks like if there is only 1 job, it will be
executed in desired mode. But if there are multiple, the most aggressive
profile will be picked, and every job will be executed in atleast the
requested power profile mode or higher.
Do you find any problem so far ?
- Shashank
Thanks,
Lijo
