public inbox for gcc-help@gcc.gnu.org
 help / color / mirror / Atom feed
From: "Anand Patil" <anand.prabhakar.patil@gmail.com>
To: gcc-help@gcc.gnu.org
Subject: OpenMP+gfortran performance extremely variable between dlopen's of libgomp
Date: Tue, 15 Jan 2008 02:33:00 -0000	[thread overview]
Message-ID: <2bc7a5a50801131919q146b8c18s76e33a811bb0db4b@mail.gmail.com> (raw)

Hi all,

As in my last help request, I'm using gfortran 4.2.1 from Ubuntu
Gutsy's apt-get, with the patch from bug 28482 (
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28482 ) applied so that I
can dlopen libgomp. I find that the performance of my subroutines
varies greatly if I reload libgomp, but if I rerun the subroutines
several times for the same load of libgomp performance is fairly
constant. Other information that may be relevant:

- The number of threads stays the same (I have OMP_DYNAMIC=False).
- The relative speedup from OpenMP (wall time / CPU time) stays
relatively constant.

I don't even know where to start looking for the source of this
behavior. Any tips?

Thanks,
Anand Patil

             reply	other threads:[~2008-01-14  3:20 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-15  2:33 Anand Patil [this message]
2008-01-15  9:19 ` Nick Maclaren

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=2bc7a5a50801131919q146b8c18s76e33a811bb0db4b@mail.gmail.com \
    --to=anand.prabhakar.patil@gmail.com \
    --cc=gcc-help@gcc.gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
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).