janwas
d1a9348b91
fix documentation of ceil_log2 relating to input=0 remove os_cpu_SetThreadAffinity (redundant) wcpu: make max # processors available via os_cpu.h; remove warning if process affinity is restricted This was SVN commit r5951.
119 lines
3.7 KiB
C++
119 lines
3.7 KiB
C++
/**
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* =========================================================================
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* File : os_cpu.h
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* Project : 0 A.D.
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* Description : OS-specific support functions relating to CPU and memory
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* =========================================================================
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*/
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// license: GPL; see lib/license.txt
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#ifndef INCLUDED_OS_CPU
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#define INCLUDED_OS_CPU
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namespace ERR
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{
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const LibError OS_CPU_RESTRICTED_AFFINITY = -130100;
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}
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//-----------------------------------------------------------------------------
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// processor topology
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// processor ID = [0, os_cpu_NumProcessors())
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// they are a numbering of the bits of the process affinity mask where the
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// least significant nonzero bit corresponds to ID 0.
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// rationale: this spares users from having to deal with noncontiguous IDs,
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// e.g. when administrative tools are used to restrict process affinity.
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/**
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* maximum number of processors supported by the OS (determined by the
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* number of bits in an affinity mask)
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**/
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static const size_t os_cpu_MaxProcessors = sizeof(uintptr_t)*CHAR_BIT;
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/**
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* @return bit mask of processors that exist and are available to
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* this process.
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* its population count is by definition equal to os_cpu_NumProcessors().
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**/
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LIB_API uintptr_t os_cpu_ProcessorMask();
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/**
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* @return the number of processors available to this process.
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*
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* note: this function is necessary because POSIX sysconf _SC_NPROCESSORS_CONF
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* is not suppored on MacOSX, else we would use that.
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**/
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LIB_API size_t os_cpu_NumProcessors();
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// note: we do not provide an os_cpu_CurrentProcessor routine. that would
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// require Windows 2003 or a lot of work. worse, its results would be
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// worthless because they may change immediately afterwards. instead,
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// the recommended approach is to pin OpenMP threads (whose ID can be
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// queried) to the processor with the same number.
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//-----------------------------------------------------------------------------
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// CPU and memory characteristics
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/**
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* @return a rough estimate of the CPU clock frequency.
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* this is usually accurate to a few MHz and is faster than measurement loops.
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**/
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LIB_API double os_cpu_ClockFrequency();
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/**
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* @return the size [bytes] of a MMU page (4096 on most IA-32 systems)
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**/
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LIB_API size_t os_cpu_PageSize();
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/**
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* @return the size [bytes] of a large MMU page (4 MiB on most IA-32 systems)
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* or zero if they are not supported.
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**/
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LIB_API size_t os_cpu_LargePageSize();
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/**
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* @return the size [bytes] of physical memory.
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**/
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LIB_API size_t os_cpu_MemorySize();
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/**
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* @return the size [bytes] of currently available memory.
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**/
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LIB_API size_t os_cpu_MemoryAvailable();
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//-----------------------------------------------------------------------------
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// scheduling
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/**
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* restrict the current thread to a set of processors.
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* it will not be rescheduled until affinity is again changed.
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*
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* @param processorMask a bit mask of acceptable processors
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* (bit index i corresponds to processor i)
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* @return the previous mask
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**/
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LIB_API uintptr_t os_cpu_SetThreadAffinityMask(uintptr_t processorMask);
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/**
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* called by os_cpu_CallByEachCPU.
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* @param processor ID of processor running the current thread for the
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* duration of this function.
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* @param cbData user-specified data passed through os_cpu_CallByEachCPU.
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**/
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typedef void (*OsCpuCallback)(size_t processor, uintptr_t cbData);
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/**
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* execute the specified function once on each processor.
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* this proceeds serially (the callback is never reentered) in increasing
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* order of processor ID.
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* fails if process affinity prevents running on all processors.
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**/
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LIB_API LibError os_cpu_CallByEachCPU(OsCpuCallback cb, uintptr_t cbData);
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#endif // #ifndef INCLUDED_OS_CPU
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