82 lines
2.4 KiB
C++
82 lines
2.4 KiB
C++
/** @file DArena.hpp
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*
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* @author Roland Conybeare, Dec 2025
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**/
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#pragma once
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#include <string>
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namespace xo {
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namespace mm {
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/** ArenaConfig
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**/
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struct ArenaConfig {
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/** optional name, for diagnostics **/
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std::string name_;
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/** arena size -- hard max = reserved virtual memory **/
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std::size_t size_;
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/** hugepage size -- using huge pages relieves some TLB pressure
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* (provided you use their full extent :)
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**/
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std::size_t hugepage_z_ = 2 * 1024 * 1024;
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/** true to enable debug logging **/
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bool debug_flag_ = false;
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};
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/** Arena allocator state
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*
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* <----------------------------size-------------------------->
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* <------------committed-----------><-------uncommitted------>
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* <--allocated-->
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*
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* XXXXXXXXXXXXXXX___________________..........................
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*
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* allocated: in use
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* committed: physical memory obtained
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* uncommitted: mapped in virtual memory, not backed by memory
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**/
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struct DArena {
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/** [lo, hi) already-mapped address range **/
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DArena(const ArenaConfig & cfg,
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std::byte * lo,
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std::byte * hi);
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~DArena();
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ArenaConfig config_;
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/** size of a VM page (via getpagesize()). Likely 4k **/
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std::size_t page_z_ = 0;
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/** arena owns memory in range [@ref lo_, @ref hi_)
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**/
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std::byte * lo_ = nullptr;
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/** prefix of this size is committed.
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* Remainder mapped but uncommitted.
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**/
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std::size_t committed_z_ = 0;
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/** free pointer.
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* Memory in range [@ref lo_, @ref free_) current in use
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**/
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std::byte * free_ = nullptr;
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/** soft limit; end of committed virtual memory
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* Memory in range [@ref lo_, @ref limit_) is committed
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* (backed by physical memory)
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**/
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std::byte * limit_ = nullptr;
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/** hard limit; end of reserved virtual memory
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* Memory in range [@ref limit_, @ref hi_) is uncommitted
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**/
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std::byte * hi_ = nullptr;
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};
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} /*namespace mm*/
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} /*namespace xo*/
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/* end DArena.hpp */
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