From: Andy Wingo <INVALID.NOREPLY@gnu.org>
To: Andy Wingo <wingo@pobox.com>, bug-guile@gnu.org
Subject: [bug #30901] High runtime variance
Date: Sun, 29 Aug 2010 19:49:06 +0000 [thread overview]
Message-ID: <20100829-194905.sv20118.717@savannah.gnu.org> (raw)
In-Reply-To:
URL:
<http://savannah.gnu.org/bugs/?30901>
Summary: High runtime variance
Project: Guile
Submitted by: wingo
Submitted on: Sun Aug 29 19:49:05 2010
Category: None
Severity: 3 - Normal
Item Group: None
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
_______________________________________________________
Details:
Luca Saiu made an interesting test case:
http://thread.gmane.org/gmane.lisp.guile.bugs/4538
It runs Guile ten times, each time running a recursive fibonacci function
three times in a row. Within each Guile run, the three fibonacci runs do take
the same amount of time, but times vary considerably between the various Guile
runs.
For example, here the run results in the following:
$ rm -rf ~/.cache/guile/; for i in `seq 10`; do
> guile --autocompile q.scm; echo; done
;;; note: autocompilation is enabled, set GUILE_AUTO_COMPILE=0
;;; or pass the --no-autocompile argument to disable.
;;; compiling q.scm
;;; compiled /home/wingo/.cache/guile/ccache/2.0-0.R-LE-8/tmp/q.scm.go
(begin (fibo n)) returned 9227465 in 3.13 seconds.
(begin (fibo n)) returned 9227465 in 3.13 seconds.
(begin (fibo n)) returned 9227465 in 3.13 seconds.
(begin (fibo n)) returned 9227465 in 3.04 seconds.
(begin (fibo n)) returned 9227465 in 3.04 seconds.
(begin (fibo n)) returned 9227465 in 3.04 seconds.
(begin (fibo n)) returned 9227465 in 3.24 seconds.
(begin (fibo n)) returned 9227465 in 3.24 seconds.
(begin (fibo n)) returned 9227465 in 3.25 seconds.
(begin (fibo n)) returned 9227465 in 3.13 seconds.
(begin (fibo n)) returned 9227465 in 3.15 seconds.
(begin (fibo n)) returned 9227465 in 3.14 seconds.
(begin (fibo n)) returned 9227465 in 3.25 seconds.
(begin (fibo n)) returned 9227465 in 3.24 seconds.
(begin (fibo n)) returned 9227465 in 3.25 seconds.
(begin (fibo n)) returned 9227465 in 3.65 seconds.
(begin (fibo n)) returned 9227465 in 3.65 seconds.
(begin (fibo n)) returned 9227465 in 3.63 seconds.
(begin (fibo n)) returned 9227465 in 3.36 seconds.
(begin (fibo n)) returned 9227465 in 3.37 seconds.
(begin (fibo n)) returned 9227465 in 3.38 seconds.
(begin (fibo n)) returned 9227465 in 3.33 seconds.
(begin (fibo n)) returned 9227465 in 3.35 seconds.
(begin (fibo n)) returned 9227465 in 3.33 seconds.
(begin (fibo n)) returned 9227465 in 3.6 seconds.
(begin (fibo n)) returned 9227465 in 3.6 seconds.
(begin (fibo n)) returned 9227465 in 3.61 seconds.
(begin (fibo n)) returned 9227465 in 3.4 seconds.
(begin (fibo n)) returned 9227465 in 3.41 seconds.
(begin (fibo n)) returned 9227465 in 3.4 seconds.
In that thread I mentioned that I suspected it was GC, but that doesn't sound
likely, as this benchmark doesn't cons. So perhaps it is indeed alignment.
The next step here is to run Guile under oprofile or perf, detecting such
things as cache misses.
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?30901>
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next reply other threads:[~2010-08-29 19:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-29 19:49 Andy Wingo [this message]
2011-06-09 16:00 ` [bug #30901] High runtime variance Stefan Israelsson Tampe
2011-06-17 18:07 ` Andy Wingo
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