This is the mail archive of the
cygwin
mailing list for the Cygwin project.
Re: Performance problem with gcc 4.9.2-3 on 64 bit
- From: Bengt Larsson <lists dot cygwin4 at bengtl dot net>
- To: cygwin at cygwin dot com
- Date: Sat, 28 Feb 2015 18:56:39 +0100
- Subject: Re: Performance problem with gcc 4.9.2-3 on 64 bit
- Authentication-results: sourceware.org; auth=none
- References: <cm61fadkltbqshdmtiil4nb50b0gf1n3qg at 4ax dot com> <54F13EA8 dot 9060609 at gmail dot com>
- Reply-to: cygwin at cygwin dot com
Marco Atzeri wrote:
>On 2/27/2015 5:49 PM, Bengt Larsson wrote:
>> Below are two benchmarks that explore maximum floating point
>> performance. loopm6 is double precision floating point and loopm6fp is
>> parallell single-precision. They are manually unrolled multiply-add
>> loops.
>>
>> I used to reach 2.8 and 11 GFlops on these. Now I only get
>> 2 and 6.
>>
>> If you explore the inner loop with gcc -O2 -S you can see that it seems
>> to use few registers.
>>
>> If you run them, there is a parameter expected. I use 30000 - 50000.
>>
>> gcc 4.9.2-3 on 64-bit. I use gcc -O2.
>>
>
>May be
>https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53967
I think that was longer ago. On the version before 4.9.* on Cygwin I got
full speed.
--
Problem reports: http://cygwin.com/problems.html
FAQ: http://cygwin.com/faq/
Documentation: http://cygwin.com/docs.html
Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple