Hi
Am 05.08.19 um 09:02 schrieb Feng Tang:
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?
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.
Best regards Thomas
[1] https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/mgag200/mgag20... [2] https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/mgag200/mgag20... [3] https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/mgag200/mgag20...
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.median14889337 -17.5% 12291029 -4.1% 14278574 vm-scalability.throughput
commit 01e75fea0d5ff39d3e588c20ec52e7a4e6588a74 Author: Feng Tang feng.tang@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@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