bug#29737: 27.0.50; pixel-scroll-mode is laggy

[Valentin Ignatyev <valentjedi@gmail.com>]

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Just tried it on mac os. pixel-scroll-mode works much better here though
there is still small noticeable lag. And also I can see that scroll up
lagging more than scroll down.
Hope it'll help


--------------------------------
С уважением,
Игнатьев Валентин

On Sat, Dec 23, 2017 at 9:30 PM, Valentin Ignatyev <valentjedi@gmail.com>
wrote:

> Hi all.
> I just tested this fix. While it doesn't solve the issue, I saw a little
> improvement. And now I see the lag pattern. When I slowly start scrolling,
> it scrolls for a while and then jumps about 10 rows at the time, then
> scrolls a bit more and jumps again
> If I swipe my trackpad too fast, emacs instantly eats 100% CPU and hangs
> infinitely (it hangs not every time, but rather once in a while. It can
> just go to the end of the file).
> If I scroll with Ctrl-key as Eli suggested in the first thread mail, it
> scrolls better than before the fix, but I still see this lag pattern
> (scroll a bit and then jump), but in the smaller scale and it doesn't kill
> emacs.
> Setting mouse-wheel-progressive-speed to nil seem to make no difference.
>
> Btw, while I do use macbook, my OS is Arch Linux here :)
> I think I'll try to compile latest emacs-26 branch on macos itself and
> tell there is defference. Maybe it'll shrink down the scope
>
> Thanks for your work on this, I really appreciate it
>
>
>
> On Sat, Dec 23, 2017 at 7:20 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>
>> > Date: Sat, 23 Dec 2017 12:18:56 +0900 (JST)
>> > Cc: valentjedi@gmail.com, 29737@debbugs.gnu.org,
>> tkk@misasa.okayama-u.ac.jp
>> > From: Tak Kunihiro <tkk@misasa.okayama-u.ac.jp>
>> >
>> > > I'd like to fix this on the release branch, not on master.  Is the
>> > > patch you sent good to go to the release branch?  Does it solve the
>> > > display lags mentioned in the bug report?
>> >
>> > Yes, the patch I sent is good to go to the release branch.
>>
>> Thanks, pushed to the release branch.
>>
>> > I'm not 100% sure what 'the display lag' meant.
>>
>> It meant very slow scrolling, with redisplay falling far behind.
>> After applying the patch, I see a definite improvement on my system.
>>
>> > After the patch, at least I tested with MacBook and do not recognize
>> > 'the display lag'.
>>
>> Right.  Valentin, could you please see whether this change makes the
>> problem go away, or at least makes it much less of a problem?  TIA.
>>
>
>

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