[drm/mgag200] 90f479ae51: vm-scalability.median -18.8% regression
Thomas Zimmermann
tzimmermann at suse.de
Mon Aug 5 10:25:50 UTC 2019
Hi
Am 05.08.19 um 09:28 schrieb Rong Chen:
> Hi,
>
> On 8/5/19 3:02 PM, Feng Tang wrote:
>> Hi Thomas,
>>
>> On Sun, Aug 04, 2019 at 08:39:19PM +0200, Thomas Zimmermann wrote:
>>> Hi
>>>
>>> I did some further analysis on this problem and found that the blinking
>>> cursor affects performance of the vm-scalability test case.
>>>
>>> I only have a 4-core machine, so scalability is not really testable. Yet
>>> I see the effects of running vm-scalibility against drm-tip, a revert of
>>> the mgag200 patch and the vmap fixes that I posted a few days ago.
>>>
>>> After reverting the mgag200 patch, running the test as described in the
>>> report
>>>
>>> bin/lkp run job.yaml
>>>
>>> gives results like
>>>
>>> 2019-08-02 19:34:37 ./case-anon-cow-seq-hugetlb
>>> 2019-08-02 19:34:37 ./usemem --runtime 300 -n 4 --prealloc
>>> --prefault
>>> -O -U 815395225
>>> 917319627 bytes / 756534 usecs = 1184110 KB/s
>>> 917319627 bytes / 764675 usecs = 1171504 KB/s
>>> 917319627 bytes / 766414 usecs = 1168846 KB/s
>>> 917319627 bytes / 777990 usecs = 1151454 KB/s
>>>
>>> Running the test against current drm-tip gives slightly worse results,
>>> such as.
>>>
>>> 2019-08-03 19:17:06 ./case-anon-cow-seq-hugetlb
>>> 2019-08-03 19:17:06 ./usemem --runtime 300 -n 4 --prealloc
>>> --prefault
>>> -O -U 815394406
>>> 917318700 bytes / 871607 usecs = 1027778 KB/s
>>> 917318700 bytes / 894173 usecs = 1001840 KB/s
>>> 917318700 bytes / 919694 usecs = 974040 KB/s
>>> 917318700 bytes / 923341 usecs = 970193 KB/s
>>>
>>> The test puts out roughly one result per second. Strangely sending the
>>> output to /dev/null can make results significantly worse.
>>>
>>> bin/lkp run job.yaml > /dev/null
>>>
>>> 2019-08-03 19:23:04 ./case-anon-cow-seq-hugetlb
>>> 2019-08-03 19:23:04 ./usemem --runtime 300 -n 4 --prealloc
>>> --prefault
>>> -O -U 815394406
>>> 917318700 bytes / 1207358 usecs = 741966 KB/s
>>> 917318700 bytes / 1210456 usecs = 740067 KB/s
>>> 917318700 bytes / 1216572 usecs = 736346 KB/s
>>> 917318700 bytes / 1239152 usecs = 722929 KB/s
>>>
>>> I realized that there's still a blinking cursor on the screen, which I
>>> disabled with
>>>
>>> tput civis
>>>
>>> or alternatively
>>>
>>> echo 0 > /sys/devices/virtual/graphics/fbcon/cursor_blink
>>>
>>> Running the the test now gives the original or even better results,
>>> such as
>>>
>>> bin/lkp run job.yaml > /dev/null
>>>
>>> 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.
>
> I set "echo 0 > /sys/devices/virtual/graphics/fbcon/cursor_blink" for
> both commits,
> and the regression has no obvious change.
Ah, I see. Thank you for testing. There are two questions that come to
my mind: did you send the regular output to /dev/null? And what happens
if you disable the cursor with 'tput civis'?
If there is absolutely nothing changing on the screen, I don't see how
the regression could persist.
Best regards
Thomas
> commit:
> f1f8555dfb9 drm/bochs: Use shadow buffer for bochs framebuffer console
> 90f479ae51a drm/mgag200: Replace struct mga_fbdev with generic
> framebuffer emulation
>
> f1f8555dfb9a70a2 90f479ae51afa45efab97afdde testcase/testparams/testbox
> ---------------- -------------------------- ---------------------------
> %stddev change %stddev
> \ | \
> 43394 -20% 34575 ± 3%
> vm-scalability/performance-300s-8T-anon-cow-seq-hugetlb/lkp-knm01
> 43393 -20% 34575 GEO-MEAN
> vm-scalability.median
>
> Best Regards,
> Rong Chen
>
>>
>> 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?
>>
>> 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)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/dri-devel/attachments/20190805/8ff2aaa8/attachment-0001.sig>
More information about the dri-devel
mailing list