[PATCH v4 00/11] Preemption support for A7XX
Antonino Maniscalco
antomani103 at gmail.com
Tue Sep 24 17:45:34 UTC 2024
On 9/24/24 4:47 PM, Rob Clark wrote:
> On Tue, Sep 24, 2024 at 4:54 AM Antonino Maniscalco
> <antomani103 at gmail.com> wrote:
>>
>> On 9/20/24 7:09 PM, Akhil P Oommen wrote:
>>> 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 at gmail.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 at linaro.org> # on SM8550-QRD
>>>> Tested-by: Neil Armstrong <neil.armstrong at linaro.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.
>>
>> I think that is because GL applications (so most compositors) run
>> through zink which does not forward GL preemption to vulkan so yeah, for
>> GL applications the only way of getting preemption is the debug flag.
>
> I guess if it is mesa 24.2.x or newer it would be using the gallium
> driver. Which I guess would need xAMBLE stuff wired up. Outside of
> fd6_emit_restore() and fd6_gmem.cc there isn't really any state emit
> in IB1, so I guess it probably wouldn't be too hard to get preemption
> support wired up.
I hadn't realized a7xx supportd had landed for the gallium driver.
That's good news! This is definitely a shorter path towards getting
compositors to use preemption.
>
> BR,
> -R
>
>> Unfortunately this is not easy to fix in Zink because it creates one
>> VkDevice at screen creation and uses it for all GL contexts. Since GL
>> priority is provided per context and at context creation time Zink has
>> no way of handling this.
>>
>> Once TU will support more than one queue it will be possible for Zink to
>> create one queue per priority then pick one at context creation time.
>> Doing so would require a new vulkan extension for per queue global
>> priority. I had started working on this some time ago
>> https://gitlab.freedesktop.org/antonino/mesa/-/tree/priority_ext?ref_type=heads
>> but this solution will only be viable once TU can expose more than one
>> queue.
>>
>>>
>>> If possible it is a good idea to check the new preemption traces to
>>> ensure preemption kicks in.
>>>
>>> -Akhil
>>>
>>>> Thanks,
>>>> Neil
>>
>>
>> Best regards,
>> --
>> Antonino Maniscalco <antomani103 at gmail.com>
Best regards,
--
Antonino Maniscalco <antomani103 at gmail.com>
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