hg: jdk7/hotspot-gc/hotspot: 6973570: OrderAccess::storestore() scales poorly on multi-socket x64 and sparc: cache-line ping-ponging

[y.s.ramakrishna at oracle.com]

Changeset: a6bff45449bc
Author:    ysr
Date:      2010-08-10 14:53 -0700
URL:       http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/a6bff45449bc

6973570: OrderAccess::storestore() scales poorly on multi-socket x64 and sparc: cache-line ping-ponging
Summary: volatile store to static variable removed in favour of a volatile store to stack to avoid excessive cache coherency traffic; verified that the volatile store is not elided by any of our current compilers.
Reviewed-by: dholmes, dice, jcoomes, kvn

! src/os_cpu/linux_sparc/vm/orderAccess_linux_sparc.inline.hpp
! src/os_cpu/linux_x86/vm/orderAccess_linux_x86.inline.hpp
! src/os_cpu/solaris_sparc/vm/orderAccess_solaris_sparc.inline.hpp
! src/os_cpu/solaris_x86/vm/orderAccess_solaris_x86.inline.hpp
! src/os_cpu/windows_x86/vm/orderAccess_windows_x86.inline.hpp
! src/share/vm/runtime/orderAccess.cpp
! src/share/vm/runtime/orderAccess.hpp