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Subject: Re: [PATCH] drm/lima: add governor data with pre-defined thresholds
From:   Christian Hewitt <christianshewitt@gmail.com>
In-Reply-To: <88ae6467-07fc-2c4e-9db9-a02a00d01347@arm.com>
Date:   Wed, 27 Jan 2021 23:35:01 +0400
Cc:     Qiang Yu <yuq825@gmail.com>, David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, lima@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, Steven Price <steven.price@arm.com>
Content-Transfer-Encoding: quoted-printable
Message-Id: <08B992A3-6A8C-4585-8B0D-EE0DA6C5F4E2@gmail.com>
References: <20210125081804.13016-1-christianshewitt@gmail.com>
 <9e30a8e1-ef69-5929-17f1-cdb603686495@arm.com>
 <88ae6467-07fc-2c4e-9db9-a02a00d01347@arm.com>
To:     Lukasz Luba <lukasz.luba@arm.com>
Precedence: bulk


> On 27 Jan 2021, at 3:11 pm, Lukasz Luba <lukasz.luba@arm.com> wrote:
>=20
> On 1/27/21 10:24 AM, Lukasz Luba wrote:
>> Hi Christian,
>> On 1/25/21 8:18 AM, Christian Hewitt wrote:
>>> This patch adapts the panfrost pre-defined thresholds change [0] to =
the
>>> lima driver to improve real-world performance. The upthreshold value =
has
>>> been set to ramp GPU frequency to max freq faster (compared to =
panfrost)
>>> to compensate for the lower overall performance of utgard devices.
>>>=20
>>> [0] =
https://patchwork.kernel.org/project/dri-devel/patch/20210121170445.19761-=
1-lukasz.luba@arm.com/=20
>>>=20
>>> Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
>>> ---
>>> I have been using Kodi as my test application. If you scroll in =
library
>>> views with hundreds of list items and the panfrost values the slow =
GPU
>>> ramp up is quite noticeable and the GUI feels sluggish. As =
everything
>>> lima runs on is inherently slower than panfrost using devices I =
believe
>>> it's better to ramp up to max freq quicker.
>> It's quite low value for the upthreshold, but I believe you have
>> experimented and observed that a bit higher (30, 40?) don't work =
well.
>> I don't know the Kodi system, though.
>> You can check if the other frequencies are also used in statistics =
for
>> devfreq device:
>> cat /sys/class/devfreq/<your_gpu>/trans_stats
>> If they are also used, then it OK (better than stuck at min freq).
>=20
> I've just realized that your board might suffer a another issue.
> Please apply this patch [1] and run your experiments with =
upthresholds.
>=20
> [1] =
https://lore.kernel.org/lkml/20210127105121.20345-1-lukasz.luba@arm.com/

I=E2=80=99ve included the patch and with unscientific testing it feels =
snappier with a larger value than
before. I did revert back to 45 first, but again this feels sluggish =
when navigating around the
Kodi GUI. My main test is to enter =E2=80=98Movies=E2=80=99 in Kodi then =
start scrolling in a long list. When
the GPU ramps up quickly the experience is snappy, but when it ramps =
more conservatively
scrolling feels like it stutters, then (once you hit max freq) it =
becomes fluid.

WP2:~ # cat /sys/class/devfreq/d00c0000.gpu/trans_stat=20
     =46rom  :   To
           : 125000000 250000000 285714285 400000000 500000000 666666666 =
744000000   time(ms)
* 125000000:         0         0         0         0         0         0 =
      264     52720
  250000000:         9         0         0         0         0         0 =
       36      3404
  285714285:         9         3         0         0         0         0 =
       32      2628
  400000000:        18        20        13         0         0         0 =
      191     21140
  500000000:        12        12         8        63         0         0 =
       31     10068
  666666666:       179         5        16       133        66         0 =
       24     29360
  744000000:        37         5         7        46        60       423 =
        0     46016

I=E2=80=99ll send v2 with the value set to 30.

Christian=