* An unexplained 10% speed-up with gcc-4.8
@ 2013-12-23 10:40 Michael Veksler
2013-12-23 13:27 ` Michael Veksler
0 siblings, 1 reply; 2+ messages in thread
From: Michael Veksler @ 2013-12-23 10:40 UTC (permalink / raw)
To: gcc
Hello All,
When I started using gcc-4.8.1 I was glad to observe a substantial
speed-up of about 10% in my code, as compared with gcc-4.7.3.
Usually, switching to newer compilers has a relatively minor effect
and definitely not a 10% speed-up. Was there anything significant
in gcc-4.8.1 which may explain this dramatic improvement?
My code is C++98 which is compiled with profile-driven optimizations,
with -O2. My target is generic 32 bit Intel architecture. The result is run
on Intel Xeon. The application is CPU intensive.
Michael
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: An unexplained 10% speed-up with gcc-4.8
2013-12-23 10:40 An unexplained 10% speed-up with gcc-4.8 Michael Veksler
@ 2013-12-23 13:27 ` Michael Veksler
0 siblings, 0 replies; 2+ messages in thread
From: Michael Veksler @ 2013-12-23 13:27 UTC (permalink / raw)
To: gcc
On 23/12/13 12:40, Michael Veksler wrote:
> Hello All,
>
> When I started using gcc-4.8.1 I was glad to observe a substantial
> speed-up of about 10% in my code, as compared with gcc-4.7.3.
>
> Usually, switching to newer compilers has a relatively minor effect
> and definitely not a 10% speed-up. Was there anything significant
> in gcc-4.8.1 which may explain this dramatic improvement?
>
> My code is C++98 which is compiled with profile-driven optimizations,
> with -O2. My target is generic 32 bit Intel architecture. The result
> is run
> on Intel Xeon. The application is CPU intensive.
>
After some more testing, I found out that there is about 12% improvement
even when comparing two executables compiled without profile-driven
optimization.
Unfortunately, the vast improvement is observed only for x86, not for
x86-64. The speed-up on x86-64 is "only" 2-3%.
Michael.
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2013-12-23 13:27 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-12-23 10:40 An unexplained 10% speed-up with gcc-4.8 Michael Veksler
2013-12-23 13:27 ` Michael Veksler
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).