[Intel-gfx] [PATCH 5/8] drm/i915/perf: lock powergating configuration to default when active
Lionel Landwerlin
lionel.g.landwerlin at intel.com
Tue Aug 14 14:59:58 UTC 2018
Hey Tvrtko,
Thanks for taking over this series.
I've been talking to developers using the i915/perf interface and from
their point of view, they expect the system to be in a stable
configuration when doing measurements.
One issue with this patch on Gen11 is that it will lock the system in a
configuration that isn't workable for media workloads (all subslices
enabled).
So I think we should set the value for the locked configuration per
generation (gen8-10: all slices/subslices, gen11: only subslices that
contain VME samplers) so that we always get a functional configurations
for all workloads.
Could we want to select that configuration when opening perf?
Another question is how do we expose the selected value to the user. But
that can be solved in a different series.
Cheers,
-
Lionel
On 14/08/18 15:40, Tvrtko Ursulin wrote:
> From: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>
> If some of the contexts submitting workloads to the GPU have been
> configured to shutdown slices/subslices, we might loose the NOA
> configurations written in the NOA muxes.
>
> One possible solution to this problem is to reprogram the NOA muxes
> when we switch to a new context. We initially tried this in the
> workaround batchbuffer but some concerns where raised about the cost
> of reprogramming at every context switch. This solution is also not
> without consequences from the userspace point of view. Reprogramming
> of the muxes can only happen once the powergating configuration has
> changed (which happens after context switch). This means for a window
> of time during the recording, counters recorded by the OA unit might
> be invalid. This requires userspace dealing with OA reports to discard
> the invalid values.
>
> Minimizing the reprogramming could be implemented by tracking of the
> last programmed configuration somewhere in GGTT and use MI_PREDICATE
> to discard some of the programming commands, but the command streamer
> would still have to parse all the MI_LRI instructions in the
> workaround batchbuffer.
>
> Another solution, which this change implements, is to simply disregard
> the user requested configuration for the period of time when i915/perf
> is active. There is no known issue with this apart from a performance
> penality for some media workloads that benefit from running on a
> partially powergated GPU. We already prevent RC6 from affecting the
> programming so it doesn't sound completely unreasonable to hold on
> powergating for the same reason.
>
> v2: Leave RPCS programming in intel_lrc.c (Lionel)
>
> v3: Update for s/union intel_sseu/struct intel_sseu/ (Lionel)
> More to_intel_context() (Tvrtko)
> s/dev_priv/i915/ (Tvrtko)
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 15 +++++++++++++++
> drivers/gpu/drm/i915/i915_perf.c | 23 ++++++++++++++++++-----
> drivers/gpu/drm/i915/intel_lrc.c | 11 +++++++----
> drivers/gpu/drm/i915/intel_lrc.h | 3 +++
> 4 files changed, 43 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index d6049c3f911b..5c12d2676435 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -3851,4 +3851,19 @@ static inline int intel_hws_csb_write_index(struct drm_i915_private *i915)
> return I915_HWS_CSB_WRITE_INDEX;
> }
>
> +static inline struct intel_sseu
> +intel_engine_prepare_sseu(struct intel_engine_cs *engine,
> + struct intel_sseu sseu)
> +{
> + struct drm_i915_private *i915 = engine->i915;
> +
> + /*
> + * If i915/perf is active, we want a stable powergating configuration
> + * on the system. The most natural configuration to take in that case
> + * is the default (i.e maximum the hardware can do).
> + */
> + return i915->perf.oa.exclusive_stream ?
> + intel_device_default_sseu(i915) : sseu;
> +}
> +
> #endif
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> index ccb20230df2c..c2fc2399e0ed 100644
> --- a/drivers/gpu/drm/i915/i915_perf.c
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -1631,7 +1631,8 @@ static void hsw_disable_metric_set(struct drm_i915_private *dev_priv)
> */
> static void gen8_update_reg_state_unlocked(struct i915_gem_context *ctx,
> u32 *reg_state,
> - const struct i915_oa_config *oa_config)
> + const struct i915_oa_config *oa_config,
> + struct intel_sseu sseu)
> {
> struct drm_i915_private *dev_priv = ctx->i915;
> u32 ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
> @@ -1677,6 +1678,9 @@ static void gen8_update_reg_state_unlocked(struct i915_gem_context *ctx,
>
> CTX_REG(reg_state, state_offset, flex_regs[i], value);
> }
> +
> + CTX_REG(reg_state, CTX_R_PWR_CLK_STATE, GEN8_R_PWR_CLK_STATE,
> + gen8_make_rpcs(&INTEL_INFO(dev_priv)->sseu, sseu));
> }
>
> /*
> @@ -1807,6 +1811,7 @@ static int gen8_switch_to_updated_kernel_context(struct drm_i915_private *dev_pr
> static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
> const struct i915_oa_config *oa_config)
> {
> + struct intel_sseu default_sseu = intel_device_default_sseu(dev_priv);
> struct intel_engine_cs *engine = dev_priv->engine[RCS];
> struct i915_gem_context *ctx;
> int ret;
> @@ -1854,7 +1859,8 @@ static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
> ce->state->obj->mm.dirty = true;
> regs += LRC_STATE_PN * PAGE_SIZE / sizeof(*regs);
>
> - gen8_update_reg_state_unlocked(ctx, regs, oa_config);
> + gen8_update_reg_state_unlocked(ctx, regs, oa_config,
> + oa_config ? default_sseu : ce->sseu);
>
> i915_gem_object_unpin_map(ce->state->obj);
> }
> @@ -2226,14 +2232,21 @@ void i915_oa_init_reg_state(struct intel_engine_cs *engine,
> struct i915_gem_context *ctx,
> u32 *reg_state)
> {
> + struct drm_i915_private *i915 = engine->i915;
> struct i915_perf_stream *stream;
>
> if (engine->id != RCS)
> return;
>
> - stream = engine->i915->perf.oa.exclusive_stream;
> - if (stream)
> - gen8_update_reg_state_unlocked(ctx, reg_state, stream->oa_config);
> + stream = i915->perf.oa.exclusive_stream;
> + if (stream) {
> + struct intel_sseu default_sseu =
> + intel_device_default_sseu(i915);
> +
> + gen8_update_reg_state_unlocked(ctx, reg_state,
> + stream->oa_config,
> + default_sseu);
> + }
> }
>
> /**
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 7b2f2d6bb057..8a2997be7ef7 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -2484,8 +2484,8 @@ int logical_xcs_ring_init(struct intel_engine_cs *engine)
> return logical_ring_init(engine);
> }
>
> -static u32 make_rpcs(const struct sseu_dev_info *sseu,
> - struct intel_sseu ctx_sseu)
> +u32 gen8_make_rpcs(const struct sseu_dev_info *sseu,
> + struct intel_sseu ctx_sseu)
> {
> u32 rpcs = 0;
>
> @@ -2635,10 +2635,13 @@ static void execlists_init_reg_state(u32 *regs,
> }
>
> if (rcs) {
> + struct intel_sseu sseu = to_intel_context(ctx, engine)->sseu;
> +
> regs[CTX_LRI_HEADER_2] = MI_LOAD_REGISTER_IMM(1);
> CTX_REG(regs, CTX_R_PWR_CLK_STATE, GEN8_R_PWR_CLK_STATE,
> - make_rpcs(&INTEL_INFO(dev_priv)->sseu,
> - to_intel_context(ctx, engine)->sseu));
> + gen8_make_rpcs(&INTEL_INFO(dev_priv)->sseu,
> + intel_engine_prepare_sseu(engine,
> + sseu)));
>
> i915_oa_init_reg_state(engine, ctx, regs);
> }
> diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
> index f5a5502ecf70..bf3acdc3d0af 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.h
> +++ b/drivers/gpu/drm/i915/intel_lrc.h
> @@ -104,4 +104,7 @@ void intel_lr_context_resume(struct drm_i915_private *dev_priv);
>
> void intel_execlists_set_default_submission(struct intel_engine_cs *engine);
>
> +u32 gen8_make_rpcs(const struct sseu_dev_info *sseu,
> + struct intel_sseu ctx_sseu);
> +
> #endif /* _INTEL_LRC_H_ */
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