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109 lines
3.8 KiB
C
109 lines
3.8 KiB
C
/* Copyright (C) 2006 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#ifndef _atomic_h_cleanup_
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#define _atomic_h_cleanup_ "atomic/generic-msvc.h"
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/*
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We don't implement anything specific for MY_ATOMIC_MODE_DUMMY, always use
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intrinsics.
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8 and 16-bit atomics are not implemented, but it can be done if necessary.
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*/
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/*
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x86 compilers (both VS2003 or VS2005) never use instrinsics, but generate
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function calls to kernel32 instead, even in the optimized build.
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We force intrinsics as described in MSDN documentation for
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_InterlockedCompareExchange.
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*/
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#ifdef _M_IX86
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#if (_MSC_VER >= 1400)
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#include <intrin.h>
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#else
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/*Visual Studio 2003 and earlier do not have prototypes for atomic intrinsics*/
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LONG _InterlockedExchange (LONG volatile *Target,LONG Value);
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LONG _InterlockedCompareExchange (LONG volatile *Target, LONG Value, LONG Comp);
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LONG _InterlockedExchangeAdd (LONG volatile *Addend, LONG Value);
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#pragma intrinsic(_InterlockedExchangeAdd)
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#pragma intrinsic(_InterlockedCompareExchange)
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#pragma intrinsic(_InterlockedExchange)
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#endif
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#define InterlockedExchange _InterlockedExchange
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#define InterlockedExchangeAdd _InterlockedExchangeAdd
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#define InterlockedCompareExchange _InterlockedCompareExchange
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/*
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No need to do something special for InterlockedCompareExchangePointer
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as it is a #define to InterlockedCompareExchange. The same applies to
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InterlockedExchangePointer.
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*/
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#endif /*_M_IX86*/
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#define MY_ATOMIC_MODE "msvc-intrinsics"
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#define IL_EXCHG_ADD32(X,Y) InterlockedExchangeAdd((volatile LONG *)(X),(Y))
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#define IL_COMP_EXCHG32(X,Y,Z) InterlockedCompareExchange((volatile LONG *)(X),(Y),(Z))
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#define IL_COMP_EXCHGptr InterlockedCompareExchangePointer
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#define IL_EXCHG32 InterlockedExchange
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#define IL_EXCHGptr InterlockedExchangePointer
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#define make_atomic_add_body(S) \
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v= IL_EXCHG_ADD ## S (a, v)
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#define make_atomic_cas_body(S) \
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int ## S initial_cmp= *cmp; \
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int ## S initial_a= IL_COMP_EXCHG ## S (a, set, initial_cmp); \
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if (!(ret= (initial_a == initial_cmp))) *cmp= initial_a;
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#define make_atomic_swap_body(S) \
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v= IL_EXCHG ## S (a, v)
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/*
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my_yield_processor (equivalent of x86 PAUSE instruction) should be used
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to improve performance on hyperthreaded CPUs. Intel recommends to use it in
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spin loops also on non-HT machines to reduce power consumption (see e.g
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http://softwarecommunity.intel.com/articles/eng/2004.htm)
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Running benchmarks for spinlocks implemented with InterlockedCompareExchange
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and YieldProcessor shows that much better performance is achieved by calling
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YieldProcessor in a loop - that is, yielding longer. On Intel boxes setting
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loop count in the range 200-300 brought best results.
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*/
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#ifndef YIELD_LOOPS
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#define YIELD_LOOPS 200
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#endif
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static __inline int my_yield_processor()
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{
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int i;
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for(i=0; i<YIELD_LOOPS; i++)
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{
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#if (_MSC_VER <= 1310)
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/* On older compilers YieldProcessor is not available, use inline assembly*/
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__asm { rep nop }
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#else
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YieldProcessor();
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#endif
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}
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return 1;
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}
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#define LF_BACKOFF my_yield_processor()
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#else /* cleanup */
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#undef IL_EXCHG_ADD32
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#undef IL_COMP_EXCHG32
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#undef IL_COMP_EXCHGptr
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#undef IL_EXCHG32
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#undef IL_EXCHGptr
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#endif
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