[drm/mgag200] 90f479ae51: vm-scalability.median -18.8% regression
Thomas Zimmermann
tzimmermann at suse.de
Wed Jan 8 05:20:47 UTC 2020
Hi
Am 08.01.20 um 03:25 schrieb Rong Chen:
> Hi Thomas,
>
> The previous throughput was reduced from 43955 to 35691, and there is a little increase in next-20200106,
> but there is no obvious change after the patchset:
OK, I would have hoped for some improvements. Anyway, thanks for testing.
Best regards
Thomas
>
> commit:
> f1f8555dfb ("drm/bochs: Use shadow buffer for bochs framebuffer console")
> 90f479ae51 ("drm/mgag200: Replace struct mga_fbdev with generic framebuffer emulation")
>
> f1f8555dfb9a70a2 90f479ae51afa45efab97afdde9
> ---------------- ---------------------------
> %stddev %change %stddev
> \ | \
> 43955 ± 2% -18.8% 35691 vm-scalability.median
>
> commit:
>
> 9eb1b48ca4 ("Add linux-next specific files for 20200106")
> 5f20199bac ("drm/fb-helper: Synchronize dirty worker with vblank")
>
> next-20200106 5f20199bac9b2de71fd2158b90
> ---------------- --------------------------
> %stddev change %stddev
> \ | \
> 38550 38744
> 38549 38744 vm-scalability.median
>
>
> Best Regards,
> Rong Chen
>
> On 1/6/20 9:19 PM, Thomas Zimmermann wrote:
>> Hi Feng,
>>
>> do you still have the test setup that produced the performance penalty?
>>
>> If so, could you give a try to the patchset at [1]? I think I've fixed
>> the remaining issues in earlier versions and I'd like to see if it
>> actually improves performance.
>>
>> Best regards
>> Thomas
>>
>> [1]
>> https://lists.freedesktop.org/archives/dri-devel/2019-December/247771.html
>>
>> Am 05.08.19 um 14:52 schrieb Feng Tang:
>>> Hi Thomas,
>>>
>>> On Mon, Aug 05, 2019 at 12:22:11PM +0200, Thomas Zimmermann wrote:
>>>
>>> [snip]
>>>
>>>>>> 2019-08-03 19:29:17 ./case-anon-cow-seq-hugetlb
>>>>>> 2019-08-03 19:29:17 ./usemem --runtime 300 -n 4 --prealloc --prefault
>>>>>> -O -U 815394406
>>>>>> 917318700 bytes / 659419 usecs = 1358497 KB/s
>>>>>> 917318700 bytes / 659658 usecs = 1358005 KB/s
>>>>>> 917318700 bytes / 659916 usecs = 1357474 KB/s
>>>>>> 917318700 bytes / 660168 usecs = 1356956 KB/s
>>>>>>
>>>>>> Rong, Feng, could you confirm this by disabling the cursor or blinking?
>>>>> Glad to know this method restored the drop. Rong is running the case.
>>>>>
>>>>> While I have another finds, as I noticed your patch changed the bpp from
>>>>> 24 to 32, I had a patch to change it back to 24, and run the case in
>>>>> the weekend, the -18% regrssion was reduced to about -5%. Could this
>>>>> be related?
>>>> In the original code, the fbdev console already ran with 32 bpp [1] and
>>>> 16 bpp was selected for low-end devices. [2][3] The patch only set the
>>>> same values for userspace; nothing changed for the console.
>>> I did the experiment becasue I checked the commit
>>>
>>> 90f479ae51afa4 drm/mgag200: Replace struct mga_fbdev with generic framebuffer emulation
>>>
>>> in which there is code:
>>>
>>> diff --git a/drivers/gpu/drm/mgag200/mgag200_main.c b/drivers/gpu/drm/mgag200/mgag200_main.c
>>> index b10f726..a977333 100644
>>> --- a/drivers/gpu/drm/mgag200/mgag200_main.c
>>> +++ b/drivers/gpu/drm/mgag200/mgag200_main.c
>>> @@ -162,7 +162,7 @@ int mgag200_driver_load(struct drm_device *dev, unsigned long flags)
>>> if (IS_G200_SE(mdev) && mdev->mc.vram_size < (2048*1024))
>>> dev->mode_config.preferred_depth = 16;
>>> else
>>> - dev->mode_config.preferred_depth = 24;
>>> + dev->mode_config.preferred_depth = 32;
>>> dev->mode_config.prefer_shadow = 1;
>>>
>>> My debug patch was kind of restoring of this part.
>>>
>>> Thanks,
>>> Feng
>>>
>>>> Best regards
>>>> Thomas
>>>>
>>>> [1]
>>>> https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/mgag200/mgag200_fb.c?id=5d17718997367c435dbe5341a8e270d9b19478d3#n259
>>>> [2]
>>>> https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/mgag200/mgag200_fb.c?id=5d17718997367c435dbe5341a8e270d9b19478d3#n263
>>>> [3]
>>>> https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/mgag200/mgag200_fb.c?id=5d17718997367c435dbe5341a8e270d9b19478d3#n286
>>>>
>>>>> commit:
>>>>> f1f8555dfb9 drm/bochs: Use shadow buffer for bochs framebuffer console
>>>>> 90f479ae51a drm/mgag200: Replace struct mga_fbdev with generic framebuffer emulation
>>>>> 01e75fea0d5 mgag200: restore the depth back to 24
>>>>>
>>>>> f1f8555dfb9a70a2 90f479ae51afa45efab97afdde9 01e75fea0d5ff39d3e588c20ec5
>>>>> ---------------- --------------------------- ---------------------------
>>>>> 43921 ± 2% -18.3% 35884 -4.8% 41826 vm-scalability.median
>>>>> 14889337 -17.5% 12291029 -4.1% 14278574 vm-scalability.throughput
>>>>>
>>>>> commit 01e75fea0d5ff39d3e588c20ec52e7a4e6588a74
>>>>> Author: Feng Tang <feng.tang at intel.com>
>>>>> Date: Fri Aug 2 15:09:19 2019 +0800
>>>>>
>>>>> mgag200: restore the depth back to 24
>>>>>
>>>>> Signed-off-by: Feng Tang <feng.tang at intel.com>
>>>>>
>>>>> diff --git a/drivers/gpu/drm/mgag200/mgag200_main.c b/drivers/gpu/drm/mgag200/mgag200_main.c
>>>>> index a977333..ac8f6c9 100644
>>>>> --- a/drivers/gpu/drm/mgag200/mgag200_main.c
>>>>> +++ b/drivers/gpu/drm/mgag200/mgag200_main.c
>>>>> @@ -162,7 +162,7 @@ int mgag200_driver_load(struct drm_device *dev, unsigned long flags)
>>>>> if (IS_G200_SE(mdev) && mdev->mc.vram_size < (2048*1024))
>>>>> dev->mode_config.preferred_depth = 16;
>>>>> else
>>>>> - dev->mode_config.preferred_depth = 32;
>>>>> + dev->mode_config.preferred_depth = 24;> dev->mode_config.prefer_shadow = 1;
>>>>>
>>>>> r = mgag200_modeset_init(mdev);
>>>>>
>>>>> Thanks,
>>>>> Feng
>>>>>
>>>>>> The difference between mgag200's original fbdev support and generic
>>>>>> fbdev emulation is generic fbdev's worker task that updates the VRAM
>>>>>> buffer from the shadow buffer. mgag200 does this immediately, but relies
>>>>>> on drm_can_sleep(), which is deprecated.
>>>>>>
>>>>>> I think that the worker task interferes with the test case, as the
>>>>>> worker has been in fbdev emulation since forever and no performance
>>>>>> regressions have been reported so far.
>>>>>>
>>>>>>
>>>>>> So unless there's a report where this problem happens in a real-world
>>>>>> use case, I'd like to keep code as it is. And apparently there's always
>>>>>> the workaround of disabling the cursor blinking.
>>>>>>
>>>>>> Best regards
>>>>>> Thomas
>>>>>>
>>>> --
>>>> Thomas Zimmermann
>>>> Graphics Driver Developer
>>>> SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
>>>> GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
>>>> HRB 21284 (AG Nürnberg)
>>>>
>>>
>>> _______________________________________________
>>> dri-devel mailing list
>>> dri-devel at lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>>
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer
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