perf/x86/amd/uncore: Add parameter to configure hrtimer

Introduce a module parameter for configuring the hrtimer duration in
milliseconds. The default duration is 60000 milliseconds and the intent
is to allow users to customize it to suit jitter tolerances. It should
be noted that a longer duration will reduce jitter but affect accuracy
if the programmed events cause the counters to overflow multiple times
in a single interval.

Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/6cb0101da74955fa9c8361f168ffdf481ae8a200.1744906694.git.sandipan.das@amd.com

diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
index e09bfbb4a4cdf32ef6e916d279fa32e451386217..70e0af36c3781f5240a60724c913ddfc6eaea919 100644 (file)
--- a/arch/x86/events/amd/uncore.c
+++ b/arch/x86/events/amd/uncore.c
@@ -87,6 +87,10 @@ struct amd_uncore {
 
 static struct amd_uncore uncores[UNCORE_TYPE_MAX];
 
+/* Interval for hrtimer, defaults to 60000 milliseconds */
+static unsigned int update_interval = 60 * MSEC_PER_SEC;
+module_param(update_interval, uint, 0444);
+
 static struct amd_uncore_pmu *event_to_amd_uncore_pmu(struct perf_event *event)
 {
        return container_of(event->pmu, struct amd_uncore_pmu, pmu);
@@ -545,7 +549,7 @@ static int amd_uncore_ctx_init(struct amd_uncore *uncore, unsigned int cpu)
                        }
 
                        amd_uncore_init_hrtimer(curr);
-                       curr->hrtimer_duration = 60LL * NSEC_PER_SEC;
+                       curr->hrtimer_duration = (u64)update_interval * NSEC_PER_MSEC;
 
                        cpumask_set_cpu(cpu, &pmu->active_mask);
                }