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Re: App runs 8x slower on dual core machine (with test case to replicate issue)


Zach Saw wrote:
Corinna Vinschen <corinna-cygwin <at> cygwin.com> writes:
Thanks for the testcase, but... would you mind to change it to take the
boost lib out of the picture, by using just plain pthread functions, if
possible in plain C?

Apparently someone else has already encountered similar problems in cygwin perl (http://www.nntp.perl.org/group/perl.perl5.porters/2011/07/msg174491.html)
--------------
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I can confirm the perl test case:

Using the referenced prog:
on Linux:
cyg-perl-thread-test.pl
This is perl 5, version 14, subversion 2 (v5.14.2) built for x86_64-linux-thread-multi
Processing 10 tasks in 1 threads completed in 0.468952secs
Processing 10 tasks in 4 threads completed in 0.156822secs
cat /proc/cpuinfo/Hz|sort |uniq
model name : Intel(R) Xeon(R) CPU X5660 @ 2.80GHz
cpu MHz : 1596.000



On Cygwin:
This is perl 5, version 14, subversion 2 (v5.14.2) built for cygwin-thread-multi-64int
Processing 10 tasks in 1 threads completed in 1.060806secs
Processing 10 tasks in 4 threads completed in 9.640635secs
/Users/law> cat /proc/cpuinfo|grep Hz|sort -r |uniq
model name : Intel(R) Xeon(R) CPU X5680 @ 3.33GHz
cpu MHz : 3325


---
Note -- neither of my cpu's have "HT" enabled.. So in both
cases 'threads' must use separate processes...



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