linux-kernel - Re: [PATCH 4/7] drm/msm/A6xx: Implement preemption for A7XX targets

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Message-ID: <27840bd4-aac4-49ca-9c98-60913c352076@gmail.com>
Date: Fri, 23 Aug 2024 02:19:49 +0200
From: Antonino Maniscalco <antomani103@...il.com>
To: Akhil P Oommen <quic_akhilpo@...cinc.com>
Cc: 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>,
 linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 Sharat Masetty <smasetty@...eaurora.org>
Subject: Re: [PATCH 4/7] drm/msm/A6xx: Implement preemption for A7XX targets

On 8/22/24 9:23 PM, Akhil P Oommen wrote:
> On Wed, Aug 21, 2024 at 04:34:15PM +0200, Antonino Maniscalco wrote:
>> On 8/19/24 10:08 PM, Akhil P Oommen wrote:
>>> On Thu, Aug 15, 2024 at 08:26:14PM +0200, Antonino Maniscalco wrote:
>>>> This patch implements preemption feature for A6xx targets, this allows
>>>> the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
>>>> hardware as such supports multiple levels of preemption granularities,
>>>> ranging from coarse grained(ringbuffer level) to a more fine grained
>>>> such as draw-call level or a bin boundary level preemption. This patch
>>>> enables the basic preemption level, with more fine grained preemption
>>>> support to follow.
>>>>
>>>> Signed-off-by: Sharat Masetty <smasetty@...eaurora.org>
>>>> Signed-off-by: Antonino Maniscalco <antomani103@...il.com>
>>>> ---
>>>
>>> No postamble packets which resets perfcounters? It is necessary. Also, I
>>> think we should disable preemption during profiling like we disable slumber.
>>>
>>> -Akhil.
>>>
>>
>> You mention that we disable slumber during profiling however I wasn't able
>> to find code doing that. Can you please clarify which code you are referring
>> to or a mechanism through which the kernel can know when we are profiling?
>>
> 
> Please check msm_file_private_set_sysprof().
> 
> -Akhil
> 
>> Best regards,
>> -- 
>> Antonino Maniscalco <antomani103@...il.com>
>>

I see, thank you. So as Connor said in the other message we want to 
distinguish the case of system profiling where we do want preemption and 
application level profiling where we do not want it. So sysprof is not 
the condition we want to check for to disable preemption, correct?

Best regards,
-- 
Antonino Maniscalco <antomani103@...il.com>