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/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@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 >> -- Thomas Zimmermann Graphics Driver Developer SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 21284 (AG Nürnberg)
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