performance is more poor for namd 2.12

From: Yi Huizhan (yihz_at_paratera.com)
Date: Wed Sep 13 2017 - 22:25:13 CDT

Hi, I have test the namd 2.11 and namd 2.12 on Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz.
The case is stmv, the performance result is as follows:
namd 2.11, 2 cpu with 24cores: 214.28s
namd 2.12, 2 cpu with 24cores: 276.62-314.73s

I am curious why the version 2.12 give poor performace?

My configuration is:

NAMD_ARCH = Linux-x86_64
CHARMARCH = multicore-linux64-iccstatic

FLOATOPTS = -ip -axAVX -xHOST

CXX = icpc -std=c++11
CXXOPTS = -static-intel -O2 $(FLOATOPTS)
CXXNOALIASOPTS = -O2 -fno-alias $(FLOATOPTS)
CXXCOLVAROPTS = -O2 -ip

CC = icc
COPTS = -static-intel -O2 $(FLOATOPTS)

The intel compiler version is composer_xe_2015.1.133.

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