<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - Acceleration still too slow with medium finger movements" href="https://bugs.freedesktop.org/show_bug.cgi?id=101139#c22">Comment # 22</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - Acceleration still too slow with medium finger movements" href="https://bugs.freedesktop.org/show_bug.cgi?id=101139">bug 101139</a> from <a class="email" href="mailto:peter.hutterer@who-t.net" title="Peter Hutterer <peter.hutterer@who-t.net>"> Peter Hutterer</a> <pre>Some notes after another afternoon of playing around with this: The script that produces the output above measures *physical* movements on the touchpad, thus the 'speed' on the right column represent 10mm/s physical movement, not pointer movement. IMO it makes sense that the majority comes in at below 20mm/s. Slow movements generate more events, fast movements are *short* movements with few events. I played around with a bunch of acceleration curves similar to attachment 136584. I used a linear curve instead for simplicity with varying inclines, starting acceleration at 40mm/s, inclines from 'roughly parallel to current' to 'roughly like <a href="attachment.cgi?id=136584" name="attach_136584" title="Accel Profile Comparison at Zero Speed">attachment 136584</a> <a href="attachment.cgi?id=136584&action=edit" title="Accel Profile Comparison at Zero Speed">[details]</a>'. They showed the same thing every time: the pointer is uncontrollable once we hit accel factor 3 [1] at anything but very low speeds. The fast pointer movement is multiplied by a high factor, resulting in ridiculous deltas and unpredictable pointers. A fixed factor 3 is just about controllable but would cause RSI after 5 min. I have in front of me: Lenovo T440s, Lenovo T450s, Dell XPS 13 9365, Asus E402S. All with Fedora 27, up-to-date (libinput 1.10.1). The touchpad behaviour is effectively identical [2] on all four machines. <a class="bz_bug_link bz_status_NEW " title="NEW - Add libinput events to libinput-record output" href="show_bug.cgi?id=105375">Bug 105375</a> is the next step here, once that's implemented we can at least compare full output. But right now, I know just as much as before :( All that aside, please confirm that you do *not* have a hidpi screen though. [1] factor 3 not accounting for the TP_MAGIC_SLOWDOWN, so effective factor 3 * 0.37 [2] The XPS has a hidpi screen and is slow under X, GNOME on wayland makes up for this but that's not a libinput issue.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>