On Fri, Oct 13, 2023 at 11:31:14AM +0800, Meng Li wrote:
+#define AMD_PSTATE_PREFCORE_THRESHOLD 166 +#define AMD_PSTATE_MAX_CPPC_PERF 255
+static void amd_pstate_init_prefcore(struct amd_cpudata *cpudata) +{
- int ret, prio;
- u32 highest_perf;
- static u32 max_highest_perf = 0, min_highest_perf = U32_MAX;
What serializes these things?
Also, *why* are you using u32 here, what's wrong with something like:
int max_hp = INT_MIN, min_hp = INT_MAX;
- ret = amd_pstate_get_highest_perf(cpudata->cpu, &highest_perf);
- if (ret)
return;- cpudata->hw_prefcore = true;
- /* check if CPPC preferred core feature is enabled*/
- if (highest_perf == AMD_PSTATE_MAX_CPPC_PERF) {
Which effectively means <255 (also, seems to suggest MAX_CPPC_PERF might not be the best name, hmm?)
Should you not write '>= 255' then? Just in case something 'funny' happens?
pr_debug("AMD CPPC preferred core is unsupported!\n");cpudata->hw_prefcore = false;return;- }
- if (!amd_pstate_prefcore)
return;- /* The maximum value of highest perf is 255 */
- prio = (int)(highest_perf & 0xff);
If for some weird reason you get 0x1ff or whatever above (dodgy BIOS never happens, right) then this makes sense how?
Perhaps stop sending patches at break-nek speed and think for a little while on how to write this and not be confused?
- /*
* The priorities can be set regardless of whether or not* sched_set_itmt_support(true) has been called and it is valid to* update them at any time after it has been called.*/- sched_set_itmt_core_prio(prio, cpudata->cpu);
- if (max_highest_perf <= min_highest_perf) {
if (highest_perf > max_highest_perf)max_highest_perf = highest_perf;if (highest_perf < min_highest_perf)min_highest_perf = highest_perf;if (max_highest_perf > min_highest_perf) {/** This code can be run during CPU online under the* CPU hotplug locks, so sched_set_itmt_support()* cannot be called from here. Queue up a work item* to invoke it.*/schedule_work(&sched_prefcore_work);}- }
Not a word about what serializes these variables.
+}