bug#21028: Performance regression in revision af1a69f4d17a482c359d98c00ef86fac835b5fac (Apr 2014).

[Dmitry Antipov]

On 07/10/2015 07:55 PM, Clément Pit--Claudel wrote:

> The figures are very similar to the tests above: with that patch inserting 50 
> lines takes 3 seconds,
> and without it it's instantaneous. Thus I think it's safe to say that this 
> particular patch is indeed
> responsible for the performance regression. But maybe I'm missing something?

As of c40ea1328bb33abaec14f1fc92ac2349b5ee2715, I can't reproduce this issue, 
with your fontset setup
from http://debbugs.gnu.org/cgi/bugreport.cgi?bug=21028#17. Cursor motion and 
keyboard/mouse selection
are smooth, and CPU/memory usage looks normal.

My suggestions are:

1) Re-run your timed tests from 
http://debbugs.gnu.org/cgi/bugreport.cgi?bug=21028#20 under /usr/bin/time,
not time (the latter is a simple shell builtin). /usr/bin/time also shows memory usage; 
if "bad" (current)
instance consumes more memory than "good" (with reverted change) one, there may 
be nasty GC issue.

2) 3 seconds is large enough to leave the traces in profiled runs. On 
GNU/Linux, it may be worth trying
to run under perf, both "good" and "bad" cases, and comparing reports.

Dmitry