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Message-ID: <20240920170949.vp3642gghhey3pjb@hu-akhilpo-hyd.qualcomm.com>
Date: Fri, 20 Sep 2024 22:39:49 +0530
From: Akhil P Oommen <quic_akhilpo@...cinc.com>
To: Neil Armstrong <neil.armstrong@...aro.org>
CC: Antonino Maniscalco <antomani103@...il.com>,
Rob Clark
<robdclark@...il.com>, 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>,
Jonathan Corbet <corbet@....net>, <linux-arm-msm@...r.kernel.org>,
<dri-devel@...ts.freedesktop.org>, <freedreno@...ts.freedesktop.org>,
<linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
Sharat Masetty <smasetty@...eaurora.org>
Subject: Re: [PATCH v4 00/11] Preemption support for A7XX
On Wed, Sep 18, 2024 at 09:46:33AM +0200, Neil Armstrong wrote:
> Hi,
>
> On 17/09/2024 13:14, Antonino Maniscalco wrote:
> > This series implements preemption for A7XX targets, which allows the GPU to
> > switch to an higher priority ring when work is pushed to it, reducing latency
> > for high priority submissions.
> >
> > This series enables L1 preemption with skip_save_restore which requires
> > the following userspace patches to function:
> >
> > https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30544
> >
> > A flag is added to `msm_submitqueue_create` to only allow submissions
> > from compatible userspace to be preempted, therefore maintaining
> > compatibility.
> >
> > Preemption is currently only enabled by default on A750, it can be
> > enabled on other targets through the `enable_preemption` module
> > parameter. This is because more testing is required on other targets.
> >
> > For testing on other HW it is sufficient to set that parameter to a
> > value of 1, then using the branch of mesa linked above, `TU_DEBUG=hiprio`
> > allows to run any application as high priority therefore preempting
> > submissions from other applications.
> >
> > The `msm_gpu_preemption_trigger` and `msm_gpu_preemption_irq` traces
> > added in this series can be used to observe preemption's behavior as
> > well as measuring preemption latency.
> >
> > Some commits from this series are based on a previous series to enable
> > preemption on A6XX targets:
> >
> > https://lkml.kernel.org/1520489185-21828-1-git-send-email-smasetty@codeaurora.org
> >
> > Signed-off-by: Antonino Maniscalco <antomani103@...il.com>
> > ---
> > Changes in v4:
> > - Added missing register in pwrup list
> > - Removed and rearrange barriers
> > - Renamed `skip_inline_wptr` to `restore_wptr`
> > - Track ctx seqno per ring
> > - Removed secure preempt context
> > - NOP out postamble to disable it instantly
> > - Only emit pwrup reglist once
> > - Document bv_rptr_addr
> > - Removed unused A6XX_PREEMPT_USER_RECORD_SIZE
> > - Set name on preempt record buffer
> > - Link to v3: https://lore.kernel.org/r/20240905-preemption-a750-t-v3-0-fd947699f7bc@gmail.com
> >
> > Changes in v3:
> > - Added documentation about preemption
> > - Use quirks to determine which target supports preemption
> > - Add a module parameter to force disabling or enabling preemption
> > - Clear postamble when profiling
> > - Define A6XX_CP_CONTEXT_SWITCH_CNTL_LEVEL fields in a6xx.xml
> > - Make preemption records MAP_PRIV
> > - Removed user ctx record (NON_PRIV) and patch 2/9 as it's not needed
> > anymore
> > - Link to v2: https://lore.kernel.org/r/20240830-preemption-a750-t-v2-0-86aeead2cd80@gmail.com
> >
> > Changes in v2:
> > - Added preept_record_size for X185 in PATCH 3/7
> > - Added patches to reset perf counters
> > - Dropped unused defines
> > - Dropped unused variable (fixes warning)
> > - Only enable preemption on a750
> > - Reject MSM_SUBMITQUEUE_ALLOW_PREEMPT for unsupported targets
> > - Added Akhil's Reviewed-By tags to patches 1/9,2/9,3/9
> > - Added Neil's Tested-By tags
> > - Added explanation for UAPI changes in commit message
> > - Link to v1: https://lore.kernel.org/r/20240815-preemption-a750-t-v1-0-7bda26c34037@gmail.com
> >
> > ---
> > Antonino Maniscalco (11):
> > drm/msm: Fix bv_fence being used as bv_rptr
> > drm/msm/A6XX: Track current_ctx_seqno per ring
> > drm/msm: Add a `preempt_record_size` field
> > drm/msm: Add CONTEXT_SWITCH_CNTL bitfields
> > drm/msm/A6xx: Implement preemption for A7XX targets
> > drm/msm/A6xx: Sync relevant adreno_pm4.xml changes
> > drm/msm/A6xx: Use posamble to reset counters on preemption
> > drm/msm/A6xx: Add traces for preemption
> > drm/msm/A6XX: Add a flag to allow preemption to submitqueue_create
> > drm/msm/A6xx: Enable preemption for A750
> > Documentation: document adreno preemption
> >
> > Documentation/gpu/msm-preemption.rst | 98 +++++
> > drivers/gpu/drm/msm/Makefile | 1 +
> > drivers/gpu/drm/msm/adreno/a2xx_gpu.c | 2 +-
> > drivers/gpu/drm/msm/adreno/a3xx_gpu.c | 2 +-
> > drivers/gpu/drm/msm/adreno/a4xx_gpu.c | 2 +-
> > drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 6 +-
> > drivers/gpu/drm/msm/adreno/a6xx_catalog.c | 7 +-
> > drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 325 ++++++++++++++-
> > drivers/gpu/drm/msm/adreno/a6xx_gpu.h | 174 ++++++++
> > drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 440 +++++++++++++++++++++
> > drivers/gpu/drm/msm/adreno/adreno_gpu.h | 9 +-
> > drivers/gpu/drm/msm/msm_drv.c | 4 +
> > drivers/gpu/drm/msm/msm_gpu.c | 2 +-
> > drivers/gpu/drm/msm/msm_gpu.h | 11 -
> > drivers/gpu/drm/msm/msm_gpu_trace.h | 28 ++
> > drivers/gpu/drm/msm/msm_ringbuffer.h | 18 +
> > drivers/gpu/drm/msm/msm_submitqueue.c | 3 +
> > drivers/gpu/drm/msm/registers/adreno/a6xx.xml | 7 +-
> > .../gpu/drm/msm/registers/adreno/adreno_pm4.xml | 39 +-
> > include/uapi/drm/msm_drm.h | 5 +-
> > 20 files changed, 1117 insertions(+), 66 deletions(-)
> > ---
> > base-commit: 7c626ce4bae1ac14f60076d00eafe71af30450ba
> > change-id: 20240815-preemption-a750-t-fcee9a844b39
> >
> > Best regards,
>
> I've been running vulkan-cts (1.3.7.3-0-gd71a36db16d98313c431829432a136dbda692a08 from Yocto)
> on SM8650-QRD, SM8550-QRD & SM8450-HDK boards with enable_preemption in default value
> and forced to 1, and I've seen no regression so far
>
> On SM8550, I've seen a few:
> platform 3d6a000.gmu: [drm:a6xx_hfi_send_msg.constprop.0 [msm]] *ERROR* Message HFI_H2F_MSG_GX_BW_PERF_VOTE id 2743 timed out waiting for response
> platform 3d6a000.gmu: [drm:a6xx_hfi_send_msg.constprop.0 [msm]] *ERROR* Unexpected message id 2743 on the response queue
> but it's unrelated to preempt
>
> and on SM8450:
> platform 3d6a000.gmu: [drm:a6xx_gmu_set_oob [msm]] *ERROR* Timeout waiting for GMU OOB set GPU_SET: 0x0
> msm_dpu ae01000.display-controller: [drm:hangcheck_handler [msm]] *ERROR* 7.3.0.1: hangcheck detected gpu lockup rb 0!
> msm_dpu ae01000.display-controller: [drm:hangcheck_handler [msm]] *ERROR* 7.3.0.1: completed fence: 331235
> msm_dpu ae01000.display-controller: [drm:hangcheck_handler [msm]] *ERROR* 7.3.0.1: submitted fence: 331236
> adreno 3d00000.gpu: [drm:a6xx_irq [msm]] *ERROR* gpu fault ring 0 fence 50de4 status 00800005 rb 0000/0699 ib1 0000000000000000/0000 ib2 0000000000000000/0000
> msm_dpu ae01000.display-controller: [drm:recover_worker [msm]] *ERROR* 7.3.0.1: hangcheck recover!
> msm_dpu ae01000.display-controller: [drm:recover_worker [msm]] *ERROR* 7.3.0.1: offending task: deqp-vk (/usr/lib/vulkan-cts/deqp-vk)
> msm_dpu ae01000.display-controller: [drm:recover_worker [msm]] *ERROR* 7.3.0.1: hangcheck recover!
> leading to a VK_ERROR_DEVICE_LOST, but again unrelated to preempt support.
>
> So you can also add:
> Tested-by: Neil Armstrong <neil.armstrong@...aro.org> # on SM8550-QRD
> Tested-by: Neil Armstrong <neil.armstrong@...aro.org> # on SM8450-HDK
>
Niel,
On my x1e device, all submissions were somehow going into only a single
ring, even the compositor's. Not sure why. So effectively preemption was
not really exercised. I had to force one of the two benchmark I ran
using the "highprio" mesa debug flag force submittions to ring 0.
If possible it is a good idea to check the new preemption traces to
ensure preemption kicks in.
-Akhil
> Thanks,
> Neil
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