Subject: Re: bug#46981: Severe Emacs shell mode performance regression in recent Linux-libre

From: Christopher Baines <[email-masked]>
Date: Sun, 07 Mar 2021 14:51:05 +0000

Mark H Weaver <[email-masked]> writes:

> Mark H Weaver <[email-masked]> writes:
>
>> FYI, for those who use Emacs shell mode (M-x shell), I wanted to give a
>> heads-up about a severe performance regression in Linux-libre 5.10.20,
>> and I suspect the same regression exists in 5.11.3.
>>
>> For details, see the bug report I submitted to the Emacs developers,
>> here: <https://bugs.gnu.org/46978>.
>
> I've since confirmed that reverting the two upstream commits mentioned
> in <https://bugs.gnu.org/46978> fixes the performance regression.  I've
> attached a preliminary patch for Guix that reverts those upstream
> commits for [email-masked], and which I've tested on my system.
>
> I guess that the same fix is also needed for [email-masked], but I've
> not checked.  I'll leave it to others to try applying the same reverts
> to 5.11.3 if they wish, and to decide what (if anything) should be done
> in Guix about this issue.

Ah, thanks so much for investigating this Mark! I only got as far as
asking around on #emacs.

I can confirm that 5.11.3 is affected, and that reverting to 5.10.19
avoids the issue. I haven't tried your patch yet.