I have a problem with the new version of Intel C++ Compiler 18.104.22.168 (Parallel Studio 2011 SP1). My x86 application has degradation of performance about 30-40% at multicore systems (two x5690 processors, Windows 7 x64) comparing to the same code compiled with earlier version of C++ Compiler.
Withsmaller number of cores (single i7-M640) performancesare almost the same.
After some experiments I discovered thatsimple replacement of OpenMP DLL libiomp5md.dll with the earlier version resores previous performance. In particular I replaced libiomp5md.dll version 5.0.2011.606 with libiomp5md.dll version 5.0.2011.325.
Therefore the question is: what changed in libiomp5md.dll that could be a reason of such degradation? How can I restore previous performance?
As a note: I compared performances at relatively simple problems when small number of cores were sufficient, and growing number of cores most likely caused degradation. But I want to minimize this negative effect!