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* [Bug lto/41578] New: 7% slower runtime with -flto than without
@ 2009-10-05 12:33 burnus at gcc dot gnu dot org
2009-10-05 13:10 ` [Bug lto/41578] " rguenth at gcc dot gnu dot org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: burnus at gcc dot gnu dot org @ 2009-10-05 12:33 UTC (permalink / raw)
To: gcc-bugs
AMD Athlon64 4800+ (dual core, 1MB L2 cache each, SSE, SSE2, SSE3), 4GB DDR400
with
[LTO] gfortran -march=native -ffast-math -funroll-loops -flto -O3
[noLTO] gfortran -march=opteron -ffast-math -funroll-loops -ftree-loop-linear
-ftree-vectorize -msse3
When running the Polyhedron Benchmark suite, the LTO version beats the non-LTO
version in the geometric mean value: 23.91s [100%] vs 23.83s [99%]
(http://www.polyhedron.co.uk/MFL6VW74649).
However, the capacita benchmark is significantly slower, others are also a bit
slower:
[noLTO] [LTO]
capacita 81.54 [100] 87.41 [107]
mdbx 19.49 [100] 20.07 [102]
rnflow 34.91 [100] 36.04 [103]
test_fpu 21.66 [100] 22.40 [103]
(Largest performance gain: aermod (35.14 [100], 31.46 [89]) followed by induct
(36.51 [100], 35.18 [96]); the others are 2% to 0% faster with LTO.)
--
Summary: 7% slower runtime with -flto than without
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: lto
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: burnus at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41578
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug lto/41578] 7% slower runtime with -flto than without
2009-10-05 12:33 [Bug lto/41578] New: 7% slower runtime with -flto than without burnus at gcc dot gnu dot org
@ 2009-10-05 13:10 ` rguenth at gcc dot gnu dot org
2009-10-06 12:14 ` burnus at gcc dot gnu dot org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2009-10-05 13:10 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from rguenth at gcc dot gnu dot org 2009-10-05 13:10 -------
Try enabling -fwhole-program together with -flto.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41578
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug lto/41578] 7% slower runtime with -flto than without
2009-10-05 12:33 [Bug lto/41578] New: 7% slower runtime with -flto than without burnus at gcc dot gnu dot org
2009-10-05 13:10 ` [Bug lto/41578] " rguenth at gcc dot gnu dot org
@ 2009-10-06 12:14 ` burnus at gcc dot gnu dot org
2009-10-23 19:38 ` steven at gcc dot gnu dot org
2009-10-23 22:27 ` rguenth at gcc dot gnu dot org
3 siblings, 0 replies; 5+ messages in thread
From: burnus at gcc dot gnu dot org @ 2009-10-06 12:14 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from burnus at gcc dot gnu dot org 2009-10-06 12:14 -------
(In reply to comment #1)
> Try enabling -fwhole-program together with -flto.
I did now - and thanks to sanitizing the tree, there is no failure (contrary to
using only -fwhole-program w/o -flto).
capacita is now only <1% slower; but mdbx, rnflow, and test_fpu are still 2% to
3% slower. (The overall performance [geometric mean] is still 1% faster.)
(Comparison just for fun: Pathscale 3.2.99 is (geometric mean) 9%, ifort 11.1
is 8% faster.)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41578
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug lto/41578] 7% slower runtime with -flto than without
2009-10-05 12:33 [Bug lto/41578] New: 7% slower runtime with -flto than without burnus at gcc dot gnu dot org
2009-10-05 13:10 ` [Bug lto/41578] " rguenth at gcc dot gnu dot org
2009-10-06 12:14 ` burnus at gcc dot gnu dot org
@ 2009-10-23 19:38 ` steven at gcc dot gnu dot org
2009-10-23 22:27 ` rguenth at gcc dot gnu dot org
3 siblings, 0 replies; 5+ messages in thread
From: steven at gcc dot gnu dot org @ 2009-10-23 19:38 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from steven at gcc dot gnu dot org 2009-10-23 19:38 -------
This one should just be monitored from week to week. There is so much stuff
going into the trunk right now that results vary from one day to another by +5%
to -5% in the last four days alone.
--
steven at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2009-10-23 19:38:35
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41578
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug lto/41578] 7% slower runtime with -flto than without
2009-10-05 12:33 [Bug lto/41578] New: 7% slower runtime with -flto than without burnus at gcc dot gnu dot org
` (2 preceding siblings ...)
2009-10-23 19:38 ` steven at gcc dot gnu dot org
@ 2009-10-23 22:27 ` rguenth at gcc dot gnu dot org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2009-10-23 22:27 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from rguenth at gcc dot gnu dot org 2009-10-23 22:27 -------
The bugreport is not useful in its current form anyway (no testcase). Let's
close it.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |INVALID
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41578
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2009-10-23 22:27 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2009-10-05 12:33 [Bug lto/41578] New: 7% slower runtime with -flto than without burnus at gcc dot gnu dot org
2009-10-05 13:10 ` [Bug lto/41578] " rguenth at gcc dot gnu dot org
2009-10-06 12:14 ` burnus at gcc dot gnu dot org
2009-10-23 19:38 ` steven at gcc dot gnu dot org
2009-10-23 22:27 ` rguenth at gcc dot gnu dot org
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