public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug c++/96750] New: 10-12% performance decrease in benchmark going from GCC8 to GCC9/GCC10
@ 2020-08-23  6:03 mattreecebentley at gmail dot com
  2020-08-24  8:47 ` [Bug middle-end/96750] " marxin at gcc dot gnu.org
                   ` (12 more replies)
  0 siblings, 13 replies; 14+ messages in thread
From: mattreecebentley at gmail dot com @ 2020-08-23  6:03 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96750

            Bug ID: 96750
           Summary: 10-12% performance decrease in benchmark going from
                    GCC8 to GCC9/GCC10
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mattreecebentley at gmail dot com
  Target Milestone: ---

Created attachment 49102
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49102&action=edit
Compiler output

Have recently been working on a new version of the plf::colony container
(plflib.org) and found GCC9 was giving ~10% worse performance on average in a
given benchmark than GCC8. Further investigation found GCC10 was just as bad.

The effect is repeatable across architectures - I've tested on xubuntu, windows
running nuwen mingw, and on Core2 and Haswell CPUs, with and without
-march=native specified.

Compiler flags are: -O2;-march=native;-std=c++17

Code presented is with an absolute minimum use-case - other benchmarks have not
shown such strong performance differences - including both simpler and more
complex tests.
So I cannot reduce further, please do not ask me to do so.

The benchmark in question inserts into a container initially then iterates over
container elements repeatedly, randomly erasing and/or inserting new elements.

Compilers/environments used:
Xubuntu 20: GCC8.4, GCC9.3, GCC10.0.1
Windows 7: Nuwen mingw GCC8.2, nuwen mingw GCC9.2

The attached code output is from the Xubuntu environment.

Any questions let me know. I will help where I can, but my knowledge of
assembly is limited.

Information on code components:
Nanotimer is a ~nanosecond-precision sub-timeslice cross-platform timer.
Colony is a bucket-array-like unordered sequence container.

The attached zip contains the build logs and compiler preprocessed outputs for
GCC 8.4, 9.3 and 10.0.1

Thanks-
Mat

^ permalink raw reply	[flat|nested] 14+ messages in thread
end of thread, other threads:[~2023-07-07 10:37 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-08-23  6:03 [Bug c++/96750] New: 10-12% performance decrease in benchmark going from GCC8 to GCC9/GCC10 mattreecebentley at gmail dot com
2020-08-24  8:47 ` [Bug middle-end/96750] " marxin at gcc dot gnu.org
2020-08-24  9:17 ` glisse at gcc dot gnu.org
2020-08-24  9:38 ` marxin at gcc dot gnu.org
2020-08-24 23:21 ` mattreecebentley at gmail dot com
2020-09-27 23:34 ` mattreecebentley at gmail dot com
2020-09-27 23:35 ` mattreecebentley at gmail dot com
2021-12-22 10:41 ` [Bug ipa/96750] [9/10/11/12 Regression] " pinskia at gcc dot gnu.org
2022-01-21 13:27 ` rguenth at gcc dot gnu.org
2022-05-27  9:43 ` [Bug ipa/96750] [10/11/12/13 " rguenth at gcc dot gnu.org
2022-06-28 10:41 ` jakub at gcc dot gnu.org
2022-10-19  9:21 ` rguenth at gcc dot gnu.org
2022-10-19  9:22 ` rguenth at gcc dot gnu.org
2023-07-07 10:37 ` [Bug ipa/96750] [11/12/13/14 " rguenth at gcc dot gnu.org

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).