Re: Filtering out process filters

[Dmitry Gutov]

On 05/06/2025 12:02, Eli Zaretskii wrote:

> > > In batch mode, quite a lot of display stuff is bypassed entirely, and
> > > the only frame we have there is 10x10, much smaller than anything in
> > > interactive sessions.  That should account for some differences
> > > between batch and TTY cases.
> >
> > Depends on where the profile lands.
>
> Sure, that's why I suggested 'perf'.  profiler.el is not accurate
> enough, and cannot look inside C code.

It's as much profiler.c as it is profiler.el, so if someone wanted to 
add more visibility into native code, that should be possible.

> > 2. Get rid of the bounce buffer by read(2)-ing read directly into the
> > buffer. Saves a memcpy.
>
> Again, does memcpy take any significant percentage of CPU cycles?
>
> Also, reading into the buffer will be less memory-efficient because
> you don't know in advance how many bytes will be read, so we will
> need to enlarge the gap by the value of read-process-output-max, which
> could be large.
>
> I also have a vague recollection that we already tried these
> techniques, and decided against them.  Perhaps Dmitry remembers the
> details.

We probably did not, and my intuition also is that we'll hit diminishing 
returns, if the scenario is improving a process as complex as 
Eglot/jsonrpc (and not just basic char-counting routine).

But it would be good to see someone try.