4 ms·
It appears to be at least a 150ms lag from the motion of the finger to the scroll animation in the demo video. Can someone who has a devkit do a detailed break
by jancsika 8y ago
It appears to be at least a 150ms lag from the motion of the finger to the scroll animation in the demo video.
Can someone who has a devkit do a detailed breakdown of the CPU usage during that 150ms? What processes are involved, who is waiting on whom, and how could it be improved?
- xutopia 8y agoThat is absolutely brutal lag! It would feel like using a 10 year old phone with today's bloatware!
- newnewpdro 8y agoIt's a devkit running in-development software, for all we know there's thousands of lines of logging being written somewhere while interacting with the display. What's important to take away is that the devkit is stable enough to demo, the touchscreen, display, and backlight control are all working.
- solarkraft 8y agoOne one hand: Of course. On the other hand: How good will it ever be? I'm really concerned about the UX.
- newnewpdro 8y agoDoesn't the ability to trivially iterate on the entire software stack running the device allay those concerns? If a good chunk of the GNOME/free software community ends up with a librem5 in their pockets I think userspace progress should be pretty well covered.
- jancsika 8y agoThat you can potentially read the code for the entire software stack doesn't mean you can trivially iterate on it. For example, suppose the latency culprit were Firefox's CPU-based repainting. (I don't think it is as I can scroll just fine on my Chromebook with FF.) Changing Firefox to fill the scrolled area using the old Iphone checkerboard-style as someone mentioned above is non-trivial. There's nothing Gnome devs can do to make that happen, short of stopping work on Gnome, becoming FF devs, and submitting a large patch to FF. On the other hand, having access to the entire software stack plus specs (and firmware?) for the entire phone definitely gives them a higher probability of cutting into that touch latency.
- megous 8y agoI would guess software rendering/compositing. Firefox on 4 core 1.3GHz ARMv7 with software rendering and no GPU acceleration on a FullHD monitor is qicker and has smoother scrolling than that devkit though. So who knows. It just looks like unoptimized software.
- jancsika 8y agoHow does that compare to an ARM Cortex-A17? That's what I have in my rockchip chromebook running Firefox in a chroot with no GPU acceleration at all and it scrolls just fine. Moreoever there isn't the same amount of lag from touchpad to the start of the scroll event as there is in this demo. And I'm so used to latency at this point that switching tabs in GPU-accelerated ChromeOS feels like it happens too soon. :)
- megous 8y agoI have no idea.
- craftyguy 8y agoThe Mesa driver is still under development.