Mercurial > hg > graal-compiler
changeset 1711: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
author | ysr |
---|---|
date | Tue, 10 Aug 2010 14:53:35 -0700 |
parents | 94251661de76 |
children | 2d6b74c9a797 |
files | 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 |
diffstat | 7 files changed, 33 insertions(+), 27 deletions(-) [+] |
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--- a/src/os_cpu/linux_sparc/vm/orderAccess_linux_sparc.inline.hpp Mon Aug 09 18:03:50 2010 -0700 +++ b/src/os_cpu/linux_sparc/vm/orderAccess_linux_sparc.inline.hpp Tue Aug 10 14:53:35 2010 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -36,8 +36,8 @@ } inline void OrderAccess::release() { - jint* dummy = (jint*)&dummy; - __asm__ volatile("stw %%g0, [%0]" : : "r" (dummy) : "memory"); + jint* local_dummy = (jint*)&local_dummy; + __asm__ volatile("stw %%g0, [%0]" : : "r" (local_dummy) : "memory"); } inline void OrderAccess::fence() {
--- a/src/os_cpu/linux_x86/vm/orderAccess_linux_x86.inline.hpp Mon Aug 09 18:03:50 2010 -0700 +++ b/src/os_cpu/linux_x86/vm/orderAccess_linux_x86.inline.hpp Tue Aug 10 14:53:35 2010 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2003, 2009, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -30,16 +30,18 @@ inline void OrderAccess::storeload() { fence(); } inline void OrderAccess::acquire() { - volatile intptr_t dummy; + volatile intptr_t local_dummy; #ifdef AMD64 - __asm__ volatile ("movq 0(%%rsp), %0" : "=r" (dummy) : : "memory"); + __asm__ volatile ("movq 0(%%rsp), %0" : "=r" (local_dummy) : : "memory"); #else - __asm__ volatile ("movl 0(%%esp),%0" : "=r" (dummy) : : "memory"); + __asm__ volatile ("movl 0(%%esp),%0" : "=r" (local_dummy) : : "memory"); #endif // AMD64 } inline void OrderAccess::release() { - dummy = 0; + // Avoid hitting the same cache-line from + // different threads. + volatile jint local_dummy = 0; } inline void OrderAccess::fence() {
--- a/src/os_cpu/solaris_sparc/vm/orderAccess_solaris_sparc.inline.hpp Mon Aug 09 18:03:50 2010 -0700 +++ b/src/os_cpu/solaris_sparc/vm/orderAccess_solaris_sparc.inline.hpp Tue Aug 10 14:53:35 2010 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2003, 2009, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -42,8 +42,8 @@ } inline void OrderAccess::release() { - jint* dummy = (jint*)&dummy; - __asm__ volatile("stw %%g0, [%0]" : : "r" (dummy) : "memory"); + jint* local_dummy = (jint*)&local_dummy; + __asm__ volatile("stw %%g0, [%0]" : : "r" (local_dummy) : "memory"); } inline void OrderAccess::fence() { @@ -57,7 +57,9 @@ } inline void OrderAccess::release() { - dummy = 0; + // Avoid hitting the same cache-line from + // different threads. + volatile jint local_dummy = 0; } inline void OrderAccess::fence() {
--- a/src/os_cpu/solaris_x86/vm/orderAccess_solaris_x86.inline.hpp Mon Aug 09 18:03:50 2010 -0700 +++ b/src/os_cpu/solaris_x86/vm/orderAccess_solaris_x86.inline.hpp Tue Aug 10 14:53:35 2010 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2003, 2009, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -40,7 +40,9 @@ } inline void OrderAccess::release() { - dummy = 0; + // Avoid hitting the same cache-line from + // different threads. + volatile jint local_dummy = 0; } inline void OrderAccess::fence() { @@ -53,11 +55,11 @@ extern "C" { inline void _OrderAccess_acquire() { - volatile intptr_t dummy; + volatile intptr_t local_dummy; #ifdef AMD64 - __asm__ volatile ("movq 0(%%rsp), %0" : "=r" (dummy) : : "memory"); + __asm__ volatile ("movq 0(%%rsp), %0" : "=r" (local_dummy) : : "memory"); #else - __asm__ volatile ("movl 0(%%esp),%0" : "=r" (dummy) : : "memory"); + __asm__ volatile ("movl 0(%%esp),%0" : "=r" (local_dummy) : : "memory"); #endif // AMD64 } inline void _OrderAccess_fence() {
--- a/src/os_cpu/windows_x86/vm/orderAccess_windows_x86.inline.hpp Mon Aug 09 18:03:50 2010 -0700 +++ b/src/os_cpu/windows_x86/vm/orderAccess_windows_x86.inline.hpp Tue Aug 10 14:53:35 2010 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2003, 2009, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -41,7 +41,7 @@ inline void OrderAccess::release() { // A volatile store has release semantics. - dummy = 0; + volatile jint local_dummy = 0; } inline void OrderAccess::fence() {
--- a/src/share/vm/runtime/orderAccess.cpp Mon Aug 09 18:03:50 2010 -0700 +++ b/src/share/vm/runtime/orderAccess.cpp Tue Aug 10 14:53:35 2010 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2003, 2009, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -25,8 +25,6 @@ # include "incls/_precompiled.incl" # include "incls/_orderAccess.cpp.incl" -volatile intptr_t OrderAccess::dummy = 0; - void OrderAccess::StubRoutines_fence() { // Use a stub if it exists. It may not exist during bootstrap so do // nothing in that case but assert if no fence code exists after threads have been created
--- a/src/share/vm/runtime/orderAccess.hpp Mon Aug 09 18:03:50 2010 -0700 +++ b/src/share/vm/runtime/orderAccess.hpp Tue Aug 10 14:53:35 2010 -0700 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2003, 2009, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -166,6 +166,12 @@ // and release must include a sequence point, usually via a volatile memory // access. Other ways to guarantee a sequence point are, e.g., use of // indirect calls and linux's __asm__ volatile. +// Note: as of 6973570, we have replaced the originally static "dummy" field +// (see above) by a volatile store to the stack. All of the versions of the +// compilers that we currently use (SunStudio, gcc and VC++) respect the +// semantics of volatile here. If you build HotSpot using other +// compilers, you may need to verify that no compiler reordering occurs +// across the sequence point respresented by the volatile access. // // // os::is_MP Considered Redundant @@ -297,10 +303,6 @@ static void release_store_ptr_fence(volatile intptr_t* p, intptr_t v); static void release_store_ptr_fence(volatile void* p, void* v); - // In order to force a memory access, implementations may - // need a volatile externally visible dummy variable. - static volatile intptr_t dummy; - private: // This is a helper that invokes the StubRoutines::fence_entry() // routine if it exists, It should only be used by platforms that