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Message-ID: <CAF6AEGufJhPMbyJJ7kV6-2cknmOwKD15Z5foYfje0bVjH7G0MQ@mail.gmail.com>
Date: Wed, 4 Sep 2024 07:30:16 -0700
From: Rob Clark <robdclark@...il.com>
To: Antonino Maniscalco <antomani103@...il.com>
Cc: Sean Paul <sean@...rly.run>, Konrad Dybcio <konrad.dybcio@...aro.org>,
Abhinav Kumar <quic_abhinavk@...cinc.com>, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Marijn Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, linux-arm-msm@...r.kernel.org,
dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 6/9] drm/msm/A6xx: Use posamble to reset counters on preemption
On Wed, Sep 4, 2024 at 6:39 AM Antonino Maniscalco
<antomani103@...il.com> wrote:
>
> On 8/30/24 8:32 PM, Rob Clark wrote:
> > On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
> > <antomani103@...il.com> wrote:
> >>
> >> Use the postamble to reset perf counters when switching between rings,
> >> except when sysprof is enabled, analogously to how they are reset
> >> between submissions when switching pagetables.
> >>
> >> Signed-off-by: Antonino Maniscalco <antomani103@...il.com>
> >> ---
> >> drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 14 +++++++++++++-
> >> drivers/gpu/drm/msm/adreno/a6xx_gpu.h | 6 ++++++
> >> drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 26 +++++++++++++++++++++++++-
> >> drivers/gpu/drm/msm/adreno/adreno_gpu.h | 7 +++++--
> >> 4 files changed, 49 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> >> index 1a90db5759b8..3528ecbbc1ab 100644
> >> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> >> @@ -366,7 +366,8 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
> >> static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
> >> struct a6xx_gpu *a6xx_gpu, struct msm_gpu_submitqueue *queue)
> >> {
> >> - u64 preempt_offset_priv_secure;
> >> + bool sysprof = refcount_read(&a6xx_gpu->base.base.sysprof_active) > 1;
> >> + u64 preempt_offset_priv_secure, preempt_postamble;
> >>
> >> OUT_PKT7(ring, CP_SET_PSEUDO_REG, 15);
> >>
> >> @@ -403,6 +404,17 @@ static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
> >> /* seems OK to set to 0 to disable it */
> >> OUT_RING(ring, 0);
> >> OUT_RING(ring, 0);
> >> +
> >> + if (!sysprof && a6xx_gpu->preempt_postamble_len) {
> >> + preempt_postamble = SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu);
> >> +
> >> + OUT_PKT7(ring, CP_SET_AMBLE, 3);
> >> + OUT_RING(ring, lower_32_bits(preempt_postamble));
> >> + OUT_RING(ring, upper_32_bits(preempt_postamble));
> >> + OUT_RING(ring, CP_SET_AMBLE_2_DWORDS(
> >> + a6xx_gpu->preempt_postamble_len) |
> >> + CP_SET_AMBLE_2_TYPE(KMD_AMBLE_TYPE));
> >> + }
> >
> > Hmm, ok, we set this in the submit path.. but do we need to clear it
> > somehow when transitioning from !sysprof to sysprof?
> >
>
> We can always emit the packet and 0 fields out when sysprof is enabled.
> Would that be ok for you? Only emitting it when needed might be
> nontrivial given that there are multiple rings and we would be paying
> the overhead for emitting it in the more common case (not profiling) anyway.
That sounds like it would work
> > Also, how does this interact with UMD perfctr queries, I would expect
> > they would prefer save/restore?
>
> Right so my understanding given previous discussions is that we want to
> disable preemption from userspace in that case? The vulkan extension
> requires to acquire and release a lock so we could use that to emit the
> packets that enable and disable preemption perhaps.
ack
BR,
-R
> >
> > BR,
> > -R
> >
> >> }
> >>
> >> static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
> >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> >> index 652e49f01428..2338e36c8f47 100644
> >> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> >> @@ -66,6 +66,7 @@ struct a6xx_gpu {
> >> atomic_t preempt_state;
> >> spinlock_t eval_lock;
> >> struct timer_list preempt_timer;
> >> + uint64_t preempt_postamble_len;
> >>
> >> unsigned int preempt_level;
> >> bool uses_gmem;
> >> @@ -99,6 +100,11 @@ struct a6xx_gpu {
> >> #define SCRATCH_USER_CTX_IOVA(ring_id, a6xx_gpu) \
> >> (a6xx_gpu->scratch_iova + (ring_id * sizeof(uint64_t)))
> >>
> >> +#define SCRATCH_PREEMPT_POSTAMBLE_OFFSET (100 * sizeof(u64))
> >> +
> >> +#define SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu) \
> >> + (a6xx_gpu->scratch_iova + SCRATCH_PREEMPT_POSTAMBLE_OFFSET)
> >> +
> >> /*
> >> * In order to do lockless preemption we use a simple state machine to progress
> >> * through the process.
> >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> >> index 4b61b993f75f..f586615db97e 100644
> >> --- a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> >> @@ -351,6 +351,28 @@ static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
> >> return 0;
> >> }
> >>
> >> +static void preempt_prepare_postamble(struct a6xx_gpu *a6xx_gpu)
> >> +{
> >> + u32 *postamble = a6xx_gpu->scratch_ptr + SCRATCH_PREEMPT_POSTAMBLE_OFFSET;
> >> + u32 count = 0;
> >> +
> >> + postamble[count++] = PKT7(CP_REG_RMW, 3);
> >> + postamble[count++] = REG_A6XX_RBBM_PERFCTR_SRAM_INIT_CMD;
> >> + postamble[count++] = 0;
> >> + postamble[count++] = 1;
> >> +
> >> + postamble[count++] = PKT7(CP_WAIT_REG_MEM, 6);
> >> + postamble[count++] = CP_WAIT_REG_MEM_0_FUNCTION(WRITE_EQ);
> >> + postamble[count++] = CP_WAIT_REG_MEM_1_POLL_ADDR_LO(
> >> + REG_A6XX_RBBM_PERFCTR_SRAM_INIT_STATUS);
> >> + postamble[count++] = CP_WAIT_REG_MEM_2_POLL_ADDR_HI(0);
> >> + postamble[count++] = CP_WAIT_REG_MEM_3_REF(0x1);
> >> + postamble[count++] = CP_WAIT_REG_MEM_4_MASK(0x1);
> >> + postamble[count++] = CP_WAIT_REG_MEM_5_DELAY_LOOP_CYCLES(0);
> >> +
> >> + a6xx_gpu->preempt_postamble_len = count;
> >> +}
> >> +
> >> void a6xx_preempt_fini(struct msm_gpu *gpu)
> >> {
> >> struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> >> @@ -382,10 +404,12 @@ void a6xx_preempt_init(struct msm_gpu *gpu)
> >> a6xx_gpu->skip_save_restore = 1;
> >>
> >> a6xx_gpu->scratch_ptr = msm_gem_kernel_new(gpu->dev,
> >> - gpu->nr_rings * sizeof(uint64_t), MSM_BO_WC,
> >> + PAGE_SIZE, MSM_BO_WC,
> >> gpu->aspace, &a6xx_gpu->scratch_bo,
> >> &a6xx_gpu->scratch_iova);
> >>
> >> + preempt_prepare_postamble(a6xx_gpu);
> >> +
> >> if (IS_ERR(a6xx_gpu->scratch_ptr))
> >> goto fail;
> >>
> >> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> >> index 6b1888280a83..87098567483b 100644
> >> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> >> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> >> @@ -610,12 +610,15 @@ OUT_PKT4(struct msm_ringbuffer *ring, uint16_t regindx, uint16_t cnt)
> >> OUT_RING(ring, PKT4(regindx, cnt));
> >> }
> >>
> >> +#define PKT7(opcode, cnt) \
> >> + (CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) | \
> >> + ((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23))
> >> +
> >> static inline void
> >> OUT_PKT7(struct msm_ringbuffer *ring, uint8_t opcode, uint16_t cnt)
> >> {
> >> adreno_wait_ring(ring, cnt + 1);
> >> - OUT_RING(ring, CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) |
> >> - ((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23));
> >> + OUT_RING(ring, PKT7(opcode, cnt));
> >> }
> >>
> >> struct msm_gpu *a2xx_gpu_init(struct drm_device *dev);
> >>
> >> --
> >> 2.46.0
> >>
>
> Best regards,
> --
> Antonino Maniscalco <antomani103@...il.com>
>
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