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Re: Emacs benchmark workload to run and time instead of hunch performanc


From: Emanuel Berg
Subject: Re: Emacs benchmark workload to run and time instead of hunch performance
Date: Wed, 09 Jul 2014 01:30:24 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux)

Emanuel Berg <address@hidden> did write:

> What I can see from looking a the screenshot and
> skimming the README.md this measures Emacs startup
> time (esup) - but if you read my post, I said there
> is no reason (for me at least) to do that, as I have
> the OS automatically start Emacs after booting, so
> for me it is part of the boot process. After that I
> never close Emacs until I'm done for the time being,
> closing Emacs as well as shutting down the
> computer. And that is the recommended usage. It can
> of course be interesting to measure startup time but
> for my practical situation it wouldn't hurt (really)
> if Emacs took 10 minutes to start! No, I asked for
> some benchmark workload to run that would emulate or
> to a degree actually perform what could be considered
> normal emaxing - that way, the exact same workload
> could be run with and without (emacs -Q) extensive
> configuration and the require and load of modules,
> and then the times could be compared. In C, there is
> a way of hammering the DRAM and the memory bus (both
> of which might be shared on a multiprocessor
> architecture) with memory accesses that will crash
> through the core-local caches: it is called pointer
> chasing and is basically creating lots of pointers
> and then assigning values and dereferencing the
> pointers... Pretty simple and effective. Because
> Emacs is much more complicated, the method perhaps
> must be, too (?); but actually any Elisp could be
> executed and timed this way to give some estimate.

It is as I feared. Blinded by success, the bright side
has grown complacent, allowing the dark side to regroup
unhindered. Only the super-senses of the
sleep-and-food-deprived Jedi Knights alerted us to this
grave danger!

Not-very-ambitious workload but still:

(defun bench ()
  (interactive)
  (define-abbrev global-abbrev-table "rsb" "rec.sport.boxing")
  (insert "rsb")
  (expand-abbrev)

  (insert "  3")
  (backward-char 3)
  (delete-char 2)

  (buffer-menu)

  (man "ls")

  (beginning-of-buffer) )

(progn
  (elp-instrument-function 'bench)
  (bench)
  (elp-results) )

Execution times for first invocation:

emacs -Q:

bench          1           0.038667778   0.038667778

emacs, with tons of configuration:

bench          1           0.05604648    0.05604648

Keep calling it I guess it ends up in a cache because
it gets much faster - but the emacs -Q is still faster.

So the next question is just what configs slows it down
- if there is indeed a difference there...

-- 
underground experts united


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