<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body text="#000000" bgcolor="#FFFFFF"> Hi Thomas, <div class="moz-cite-prefix">On 9/4/2019 4:43 PM, Thomas Zimmermann wrote: </div> <blockquote type="cite" cite="mid:33d3ce15-6221-bd96-3f26-b710e4da6b1a@suse.de"> <pre class="moz-quote-pre" wrap="">Hi Am 04.09.19 um 10:35 schrieb Feng Tang: </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap="">Hi Daniel, On Wed, Sep 04, 2019 at 10:11:11AM +0200, Daniel Vetter wrote: </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap="">On Wed, Sep 4, 2019 at 8:53 AM Thomas Zimmermann <a class="moz-txt-link-rfc2396E" href="mailto:tzimmermann@suse.de"><tzimmermann@suse.de></a> wrote: </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""> Hi Am 04.09.19 um 08:27 schrieb Feng Tang: </pre> <blockquote type="cite"> <blockquote type="cite"> <pre class="moz-quote-pre" wrap="">Thank you for testing. But don't get too excited, because the patch simulates a bug that was present in the original mgag200 code. A significant number of frames are simply skipped. That is apparently the reason why it's faster. </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> Thanks for the detailed info, so the original code skips time-consuming work inside atomic context on purpose. Is there any space to optmise it? If 2 scheduled update worker are handled at almost same time, can one be skipped? </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> To my knowledge, there's only one instance of the worker. Re-scheduling the worker before a previous instance started, will not create a second instance. The worker's instance will complete all pending updates. So in some way, skipping workers already happens. </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> So I think that the most often fbcon update from atomic context is the blinking cursor. If you disable that one you should be back to the old performance level I think, since just writing to dmesg is from process context, so shouldn't change. </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> Hmm, then for the old driver, it should also do the most update in non-atomic context? One other thing is, I profiled that updating a 3MB shadow buffer needs 20 ms, which transfer to 150 MB/s bandwidth. Could it be related with the cache setting of DRM shadow buffer? say the orginal code use a cachable buffer? </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""> <a class="moz-txt-link-freetext" href="https://unix.stackexchange.com/questions/3759/how-to-stop-cursor-from-blinking">https://unix.stackexchange.com/questions/3759/how-to-stop-cursor-from-blinking</a> Bunch of tricks, but tbh I haven't tested them. </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> Thomas has suggested to disable curson by echo 0 > /sys/devices/virtual/graphics/fbcon/cursor_blink We tried that way, and no change for the performance data. </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> There are several ways of disabling the cursor. On my test system, I entered tput civis before the test and got better performance. Did you try this as well?</pre> </blockquote> There's no obvious change on our system. Best Regards, Rong Chen <blockquote type="cite" cite="mid:33d3ce15-6221-bd96-3f26-b710e4da6b1a@suse.de"> <pre class="moz-quote-pre" wrap=""> Best regards Thomas </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""> Thanks, Feng </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""> In any case, I still strongly advice you don't print anything to dmesg or fbcon while benchmarking, because dmesg/printf are anything but fast, especially if a gpu driver is involved. There's some efforts to make the dmesg/printk side less painful (untangling the console_lock from printk), but fundamentally printing to the gpu from the kernel through dmesg/fbcon won't be cheap. It's just not something we optimize beyond "make sure it works for emergencies". -Daniel </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""> Best regards Thomas </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""> Thanks, Feng </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""> Best regards Thomas </pre> </blockquote> <pre class="moz-quote-pre" wrap="">_______________________________________________ dri-devel mailing list <a class="moz-txt-link-abbreviated" href="mailto:dri-devel@lists.freedesktop.org">dri-devel@lists.freedesktop.org</a> <a class="moz-txt-link-freetext" href="https://lists.freedesktop.org/mailman/listinfo/dri-devel">https://lists.freedesktop.org/mailman/listinfo/dri-devel</a> </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> -- 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 <a class="moz-txt-link-abbreviated" href="mailto:dri-devel@lists.freedesktop.org">dri-devel@lists.freedesktop.org</a> <a class="moz-txt-link-freetext" href="https://lists.freedesktop.org/mailman/listinfo/dri-devel">https://lists.freedesktop.org/mailman/listinfo/dri-devel</a> </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - <a class="moz-txt-link-freetext" href="http://blog.ffwll.ch">http://blog.ffwll.ch</a> </pre> </blockquote> </blockquote> <pre class="moz-quote-pre" wrap=""> </pre> <fieldset class="mimeAttachmentHeader"></fieldset> <pre class="moz-quote-pre" wrap="">_______________________________________________ LKP mailing list <a class="moz-txt-link-abbreviated" href="mailto:LKP@lists.01.org">LKP@lists.01.org</a> <a class="moz-txt-link-freetext" href="https://lists.01.org/mailman/listinfo/lkp">https://lists.01.org/mailman/listinfo/lkp</a> </pre> </blockquote> </body> </html>