From: Zan Lynx <zlynx@acm.org>
To: Paul Menzel <pmenzel+gcc.gnu.org@molgen.mpg.de>
Cc: gcc@gcc.gnu.org
Subject: Re: How to get GCC on par with ICC?
Date: Wed, 06 Jun 2018 22:43:00 -0000 [thread overview]
Message-ID: <0edea081-246f-6192-ae74-f55b2b23df5c@acm.org> (raw)
In-Reply-To: <CAJoDaPaxrmF80-ptO87_WxRFpUxq41uz4oDKB1mdJrFJ5ypE8A@mail.gmail.com>
On 06/06/2018 10:22 AM, Dmitry Mikushin wrote:
> The opinion you've mentioned is common in scientific community. However, in
> more detail it often surfaces that the used set of GCC compiler options
> simply does not correspond to that "fast" version of Intel. For instance,
> when you do "-O3" for Intel it actually corresponds to (at least) "-O3
> -ffast-math -march=native" of GCC. Omitting "-ffast-math" obviously
> introduces significant performance gap.
>
Please note that if your compute cluster uses different models of CPU,
be extremely careful with -march=native.
I've been bitten by it in VMs, several times. Unless you always run on
the same system that did the build, you are running a risk of illegal
instructions.
--
Knowledge is Power -- Power Corrupts
Study Hard -- Be Evil
next prev parent reply other threads:[~2018-06-06 21:10 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-06 15:57 Paul Menzel
2018-06-06 16:14 ` Joel Sherrill
2018-06-06 16:20 ` Paul Menzel
2018-06-20 22:42 ` NightStrike
2018-06-21 9:20 ` Richard Biener
2018-06-22 0:48 ` Steve Ellcey
2018-06-06 16:22 ` Bin.Cheng
2018-06-06 18:31 ` Dmitry Mikushin
2018-06-06 21:10 ` Ryan Burn
2018-06-07 10:02 ` Richard Biener
2018-06-06 22:43 ` Zan Lynx [this message]
2018-06-07 9:54 ` Richard Biener
2018-06-07 10:06 ` Richard Biener
2018-06-08 22:08 ` Steve Ellcey
2018-06-09 15:32 ` Marc Glisse
2018-06-11 14:50 ` Martin Jambor
2018-06-22 22:41 ` Szabolcs Nagy
2018-06-15 11:48 Wilco Dijkstra
2018-06-15 17:03 ` Jeff Law
2018-06-15 18:01 ` Joseph Myers
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