A fundamental assumption is that at lower frequencies,
not only do we run slower, but we save power compared to
higher frequencies.
live_slpc_power checks if running at low frequency saves power
v2: re-use code to measure power
fixed cosmetic review comments (Vinay)
Signed-off-by: Riana Tauro <riana.ta...@intel.com>
---
drivers/gpu/drm/i915/gt/selftest_slpc.c | 127 ++++++++++++++++++++++--
1 file changed, 118 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/selftest_slpc.c
b/drivers/gpu/drm/i915/gt/selftest_slpc.c
index 928f74718881..4c6e9257e593 100644
--- a/drivers/gpu/drm/i915/gt/selftest_slpc.c
+++ b/drivers/gpu/drm/i915/gt/selftest_slpc.c
@@ -11,7 +11,8 @@
enum test_type {
VARY_MIN,
VARY_MAX,
- MAX_GRANTED
+ MAX_GRANTED,
+ SLPC_POWER,
};
static int slpc_set_min_freq(struct intel_guc_slpc *slpc, u32 freq)
@@ -41,6 +42,39 @@ static int slpc_set_max_freq(struct intel_guc_slpc *slpc,
u32 freq)
return ret;
}
+static int slpc_set_freq(struct intel_gt *gt, u32 freq)
+{
+ int err;
+ struct intel_guc_slpc *slpc = >->uc.guc.slpc;
+
+ err = slpc_set_max_freq(slpc, freq);
+ if (err) {
+ pr_err("Unable to update max freq");
+ return err;
+ }
+
+ err = slpc_set_min_freq(slpc, freq);
+ if (err) {
+ pr_err("Unable to update min freq");
+ return err;
+ }
+
+ return err;
+}
+
+static u64 measure_power_at_freq(struct intel_gt *gt, int *freq, u64 *power)
+{
+ int err = 0;
+
+ err = slpc_set_freq(gt, *freq);
+ if (err)
+ return err;
+ *freq = intel_rps_read_actual_frequency(>->rps);
+ *power = measure_power(>->rps, freq);
+
+ return err;
+}
+
static int vary_max_freq(struct intel_guc_slpc *slpc, struct intel_rps *rps,
u32 *max_act_freq)
{
@@ -113,6 +147,58 @@ static int vary_min_freq(struct intel_guc_slpc *slpc,
struct intel_rps *rps,
return err;
}
+static int slpc_power(struct intel_gt *gt, struct intel_engine_cs *engine)
+{
+ struct intel_guc_slpc *slpc = >->uc.guc.slpc;
+ struct {
+ u64 power;
+ int freq;
+ } min, max;
+ int err = 0;
+
+ /*
+ * Our fundamental assumption is that running at lower frequency
+ * actually saves power. Let's see if our RAPL measurement supports
+ * that theory.
+ */
+ if (!librapl_supported(gt->i915))
+ return 0;
+
+ min.freq = slpc->min_freq;
+ err = measure_power_at_freq(gt, &min.freq, &min.power);
+
+ if (err)
+ return err;
+
+ max.freq = slpc->rp0_freq;
+ err = measure_power_at_freq(gt, &max.freq, &max.power);
+
+ if (err)
+ return err;
+
+ pr_info("%s: min:%llumW @ %uMHz, max:%llumW @ %uMHz\n",
+ engine->name,
+ min.power, min.freq,
+ max.power, max.freq);
+
+ if (10 * min.freq >= 9 * max.freq) {
+ pr_notice("Could not control frequency, ran at [%uMHz,
%uMhz]\n",
+ min.freq, max.freq);
+ }
+
+ if (11 * min.power > 10 * max.power) {
+ pr_err("%s: did not conserve power when setting lower
frequency!\n",
+ engine->name);
+ err = -EINVAL;
+ }
+
+ /* Restore min/max frequencies */
+ slpc_set_max_freq(slpc, slpc->rp0_freq);
+ slpc_set_min_freq(slpc, slpc->min_freq);
+
+ return err;
+}
+
static int max_granted_freq(struct intel_guc_slpc *slpc, struct intel_rps
*rps, u32 *max_act_freq)
{
struct intel_gt *gt = rps_to_gt(rps);
@@ -233,17 +319,23 @@ static int run_test(struct intel_gt *gt, int test_type)
err = max_granted_freq(slpc, rps, &max_act_freq);
break;
+
+ case SLPC_POWER:
+ err = slpc_power(gt, engine);
+ break;
}
- pr_info("Max actual frequency for %s was %d\n",
- engine->name, max_act_freq);
+ if (test_type != SLPC_POWER) {
+ pr_info("Max actual frequency for %s was %d\n",
+ engine->name, max_act_freq);
- /* Actual frequency should rise above min */
- if (max_act_freq <= slpc_min_freq) {
- pr_err("Actual freq did not rise above min\n");
- pr_err("Perf Limit Reasons: 0x%x\n",
- intel_uncore_read(gt->uncore,
GT0_PERF_LIMIT_REASONS));
- err = -EINVAL;
+ /* Actual frequency should rise above min */
+ if (max_act_freq <= slpc_min_freq) {
+ pr_err("Actual freq did not rise above min\n");
+ pr_err("Perf Limit Reasons: 0x%x\n",
+ intel_uncore_read(gt->uncore,
GT0_PERF_LIMIT_REASONS));
+ err = -EINVAL;
+ }
}
igt_spinner_end(&spin);
@@ -316,12 +408,29 @@ static int live_slpc_max_granted(void *arg)
return ret;
}
+static int live_slpc_power(void *arg)
+{
+ struct drm_i915_private *i915 = arg;
+ struct intel_gt *gt;
+ unsigned int i;
+ int ret;
+
+ for_each_gt(gt, i915, i) {
+ ret = run_test(gt, SLPC_POWER);
+ if (ret)
+ return ret;
+ }
+
+ return ret;
+}
+
int intel_slpc_live_selftests(struct drm_i915_private *i915)
{
static const struct i915_subtest tests[] = {
SUBTEST(live_slpc_vary_max),
SUBTEST(live_slpc_vary_min),
SUBTEST(live_slpc_max_granted),
+ SUBTEST(live_slpc_power),
};
struct intel_gt *gt;
--
2.25.1
