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.
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@xxxxxxxxx>
Date: Fri Aug 2 15:09:19 2019 +0800
mgag200: restore the depth back to 24
Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
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
>
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