[Texmacs-dev] disk caches and startup time

[David Allouche]

On Tue, May 25, 2004 at 10:24:18AM +0200, Joris van der Hoeven wrote:
> 
> On Tue, 25 May 2004, Gilles LAMIRAL wrote:
> > > But what I still don't understand is why TeXmacs
> > > is so much slower at the *first* time one boots it.
> >
> > Because code is already cached in memory.
> 
> Yes, OK, but why is it so *much* slower compared to other programs.
> The TeXmacs binary is quite small. Is it the fact that we load many
> small font, scheme, and other files?

Maybe the file loading patterns are causing a lot of hard disk head
motion, and that really kills the i/o performance (head motion time is
measured in miliseconds).

Something to try would be first reading all the relevant texmacs
files, then all the revelant tex files, then maybe some relevant guile
files to prime the disk cache. Since the files for a given software
package are likely to be close to one another on the disk, that might
end up improving the performance.

> 
> > > And this is hard to bench (modulo turning on/off the computer).
> >
> > You have to clear the cached code by running a command
> > taking all the cache memory (a simple dd ?).
> 
> What would be the exact command?

Attached is my pet memory filler, complete with an ascii spinner.

Compile with "make fill_mem". Run as "./fill_mem 1024" if your system
has 1024 MB of RAM. Do not run with a parameter which is much bigger
than your RAM or you will likely throw your system into endless
thrashing.

-- 
                                                            -- ddaa

fill_mem.c
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