On Tue, Mar 24, 2020 at 1:45 PM Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
>
> Measure and compare the energy consumed, as reported by the rapl MSR,
> by the GPU while in RC0 and RC6 states. Throw an error if RC6 does not
> at least halve the energy consumption of RC0, as this more than likely
> means we failed to enter RC0 correctly.
>
> If we can't measure the energy draw with the MSR, then it will report 0
> for both measurements. Since the measurement works on all gen6+, this seems
> worth flagging as an error.
I'm confused by this statement here. MSR is a *CPU* register and you are using
it here, mixed with RC6. How is that supposed to work with, e.g., dgfx?
thanks
Lucas De Marchi
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Cc: Andi Shyti <andi.shyti@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/selftest_rc6.c | 39 ++++++++++++++++++++++++++
> 1 file changed, 39 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/selftest_rc6.c b/drivers/gpu/drm/i915/gt/selftest_rc6.c
> index 95b165faeba7..3ac9a8925218 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_rc6.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_rc6.c
> @@ -12,6 +12,22 @@
>
> #include "selftests/i915_random.h"
>
> +#define MCH_SECP_NRG_STTS _MMIO(MCHBAR_MIRROR_BASE_SNB + 0x592c)
> +
> +static u64 energy_uJ(struct intel_rc6 *rc6)
> +{
> + unsigned long long power;
> + u32 units;
> +
> + if (rdmsrl_safe(MSR_RAPL_POWER_UNIT, &power))
> + return 0;
> +
> + units = (power & 0x1f00) >> 8;
> + power = intel_uncore_read_fw(rc6_to_uncore(rc6), MCH_SECP_NRG_STTS);
> +
> + return (1000000 * power) >> units; /* convert to uJ */
> +}
> +
> static u64 rc6_residency(struct intel_rc6 *rc6)
> {
> u64 result;
> @@ -31,7 +47,9 @@ int live_rc6_manual(void *arg)
> {
> struct intel_gt *gt = arg;
> struct intel_rc6 *rc6 = >->rc6;
> + u64 rc0_power, rc6_power;
> intel_wakeref_t wakeref;
> + ktime_t dt;
> u64 res[2];
> int err = 0;
>
> @@ -53,22 +71,35 @@ int live_rc6_manual(void *arg)
> __intel_rc6_disable(rc6);
> msleep(1); /* wakeup is not immediate, takes about 100us on icl */
>
> + dt = ktime_get();
> + rc0_power = energy_uJ(rc6);
> res[0] = rc6_residency(rc6);
> msleep(250);
> res[1] = rc6_residency(rc6);
> + rc0_power = div64_u64(energy_uJ(rc6) - rc0_power,
> + ktime_to_ns(ktime_sub(ktime_get(), dt)));
> if ((res[1] - res[0]) >> 10) {
> pr_err("RC6 residency increased by %lldus while disabled for 250ms!\n",
> (res[1] - res[0]) >> 10);
> err = -EINVAL;
> goto out_unlock;
> }
> + if (!rc0_power) {
> + pr_err("No power measured while in RC0\n");
> + err = -EINVAL;
> + goto out_unlock;
> + }
>
> /* Manually enter RC6 */
> intel_rc6_park(rc6);
>
> + dt = ktime_get();
> + rc6_power = energy_uJ(rc6);
> res[0] = rc6_residency(rc6);
> msleep(100);
> res[1] = rc6_residency(rc6);
> + rc6_power = div64_u64(energy_uJ(rc6) - rc6_power,
> + ktime_to_ns(ktime_sub(ktime_get(), dt)));
>
> if (res[1] == res[0]) {
> pr_err("Did not enter RC6! RC6_STATE=%08x, RC6_CONTROL=%08x, residency=%lld\n",
> @@ -78,6 +109,14 @@ int live_rc6_manual(void *arg)
> err = -EINVAL;
> }
>
> + pr_info("GPU consumed %llduW in RC0 and %llduW in RC6\n",
> + rc0_power, rc6_power);
> + if ((rc6_power >> 10) > (rc0_power >> 10) / 2) { /* compare mW */
> + pr_err("GPU leaked energy while in RC6!\n");
> + err = -EINVAL;
> + goto out_unlock;
> + }
> +
> /* Restore what should have been the original state! */
> intel_rc6_unpark(rc6);
>
> --
> 2.20.1
>
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