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Re: Correct line/column numbers in byte compiler messages
From: |
Alan Mackenzie |
Subject: |
Re: Correct line/column numbers in byte compiler messages |
Date: |
Sat, 21 Mar 2020 20:19:54 +0000 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
Hello, Andrea.
On Sat, Mar 21, 2020 at 18:37:13 +0000, Andrea Corallo wrote:
> Have to apologize this is probably the quarantine effect ....
As of today, we're under quarantine, too. :-(
> .... but I couldn't resist testing this:
> #+BEGIN_SRC lisp
> ;; -*- lexical-binding: t; -*-
> (require 'cl-lib)
> (defvar elb-list (cl-loop for i from 0 to 1500000
> if (cl-oddp i)
> collect 'a
> else
> collect 'b))
> (defun elb-eq ()
> (let ((n 0))
> (dolist (l elb-list n)
> (when (eq 'b l)
> (cl-incf n)))))
> (defun elb-eq-entry ()
> (dotimes (_ 1000)
> (elb-eq)))
> #+END_SRC
> Results:
> b619777dd6 (baseline) 50.09s
> accurate-warning-pos 51.28s
> This is about 2% perf penalty.
On my Ryzen, I'm seeing a 50% penalty. :-( (Admittedly that's
comparing the year old branch to current master. I suppose I should
build the correct comparable revision and try again.) This suggests
that the branch prediction logic isn't present (or isn't active) on the
Ryzen.
> Interestingly with the __builtin_expect trick applied exec time gets
> back to 50.65s.
How do you do this? I couldn't make much sense of the documentation of
__builtin_expect. :-(
> We could probably find a benchmark that better highlights the difference
> (this is potentially dominated by cache misses while pointer chasing the
> list) but is it worth?
Could I ask you to do the following timing.
Evaluate the following (e.g. in *scratch*):
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defmacro time-it (&rest forms)
"Time the running of a sequence of forms using `float-time'.
Call like this: \"M-: (time-it (foo ...) (bar ...) ...)\"."
`(let ((start (float-time)))
,@forms
(- (float-time) start)))
(defun time-scroll (&optional arg)
(interactive "P")
(message "%s"
(time-it
(condition-case nil
(while t
(if arg (scroll-down) (scroll-up))
(sit-for 0))
(error nil)))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
, visit .../emacs/src/xdisp.c, and do M-: (time-scroll). This scrolls
through the buffer and prints a timing in the minibuffer. (N.B. to run
this again, type something at BOB and undo it, thus marking the
fontification as stale.)
I'm seeing 19.4s vs. 22.2s, which is around 15% difference. :-(
> Regards
> Andrea
> --
> address@hidden
--
Alan Mackenzie (Nuremberg, Germany).
- Re: GNU is looking for Google Summer of Code Projects, (continued)
Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Alan Mackenzie, 2020/03/19
- Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Andrea Corallo, 2020/03/19
- Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Alan Mackenzie, 2020/03/20
- Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Andrea Corallo, 2020/03/21
- Re: Correct line/column numbers in byte compiler messages, Alan Mackenzie, 2020/03/21
- Re: Correct line/column numbers in byte compiler messages, Andrea Corallo, 2020/03/21
- Re: Correct line/column numbers in byte compiler messages, Andrea Corallo, 2020/03/21
- Re: Correct line/column numbers in byte compiler messages,
Alan Mackenzie <=
- Re: Correct line/column numbers in byte compiler messages, Andrea Corallo, 2020/03/21
- Re: Correct line/column numbers in byte compiler messages, Andrea Corallo, 2020/03/21
Re: Correct line/column numbers in byte compiler messages, Alan Mackenzie, 2020/03/22
Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Rocky Bernstein, 2020/03/19
Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Stefan Monnier, 2020/03/19
Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Alan Mackenzie, 2020/03/20
Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Stefan Monnier, 2020/03/19
Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Stefan Monnier, 2020/03/19
Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Alan Mackenzie, 2020/03/20
Re: Correct line/column numbers in byte compiler messages [Was: GNU is looking for Google Summer of Code Projects], Rocky Bernstein, 2020/03/20