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Reorder members of MapBlock for performance
Before and after as obtained via `pahole -C MapBlock bin/minetest`: /* size: 336, cachelines: 6, members: 23 */ /* sum members: 329, holes: 4, sum holes: 7 */ vs. /* size: 336, cachelines: 6, members: 23 */ /* sum members: 329, holes: 2, sum holes: 7 */ There is not much to be gained by packing but I made sure to move the most important data (mainly for the client) into the first cache line.
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9408a1a025
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126
src/mapblock.h
126
src/mapblock.h
@ -437,6 +437,11 @@ public:
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// clearObject and return removed objects count
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u32 clearObjects();
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static const u32 ystride = MAP_BLOCKSIZE;
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static const u32 zstride = MAP_BLOCKSIZE * MAP_BLOCKSIZE;
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static const u32 nodecount = MAP_BLOCKSIZE * MAP_BLOCKSIZE * MAP_BLOCKSIZE;
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private:
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/*
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Private methods
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@ -444,59 +449,73 @@ private:
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void deSerialize_pre22(std::istream &is, u8 version, bool disk);
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public:
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/*
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Public member variables
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*/
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* PLEASE NOTE: When adding something here be mindful of position and size
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* of member variables! This is also the reason for the weird public-private
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* interleaving.
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* If in doubt consult `pahole` to see the effects.
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*/
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public:
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#ifndef SERVER // Only on client
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MapBlockMesh *mesh = nullptr;
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// marks the sides which are opaque: 00+Z-Z+Y-Y+X-X
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u8 solid_sides = 0;
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#endif
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NodeMetadataList m_node_metadata;
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StaticObjectList m_static_objects;
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static const u32 ystride = MAP_BLOCKSIZE;
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static const u32 zstride = MAP_BLOCKSIZE * MAP_BLOCKSIZE;
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static const u32 nodecount = MAP_BLOCKSIZE * MAP_BLOCKSIZE * MAP_BLOCKSIZE;
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//// ABM optimizations ////
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// Cache of content types
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// This is actually a set but for the small sizes we have a vector should be
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// more efficient.
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// Can be empty, in which case nothing was cached yet.
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std::vector<content_t> contents;
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// True if we never want to cache content types for this block
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bool do_not_cache_contents = false;
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// marks the sides which are opaque: 00+Z-Z+Y-Y+X-X
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u8 solid_sides {0};
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private:
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/*
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Private member variables
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*/
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// see isOrphan()
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bool m_orphan = false;
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// Position in blocks on parent
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v3s16 m_pos;
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/* This is the precalculated m_pos_relative value
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* This caches the value, improving performance by removing 3 s16 multiplications
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* at runtime on each getPosRelative call
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* For a 5 minutes runtime with valgrind this removes 3 * 19M s16 multiplications
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* The gain can be estimated in Release Build to 3 * 100M multiply operations for 5 mins
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*/
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/* Precalculated m_pos_relative value
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* This caches the value, improving performance by removing 3 s16 multiplications
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* at runtime on each getPosRelative call.
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* For a 5 minutes runtime with valgrind this removes 3 * 19M s16 multiplications.
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* The gain can be estimated in Release Build to 3 * 100M multiply operations for 5 mins.
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*/
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v3s16 m_pos_relative;
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/*
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* Note that this is not an inline array because that has implications on
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Reference count; currently used for determining if this block is in
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the list of blocks to be drawn.
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*/
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short m_refcount = 0;
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/*
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* Note that this is not an inline array because that has implications for
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* heap fragmentation (the array is exactly 16K), CPU caches and/or
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* optimizability of algorithms working on this array.
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*/
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MapNode *const data; // of `nodecount` elements
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// provides the item and node definitions
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IGameDef *m_gamedef;
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/*
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When the block is accessed, this is set to 0.
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Map will unload the block when this reaches a timeout.
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*/
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float m_usage_timer = 0;
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public:
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//// ABM optimizations ////
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// True if we never want to cache content types for this block
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bool do_not_cache_contents = false;
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// Cache of content types
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// This is actually a set but for the small sizes we have a vector should be
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// more efficient.
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// Can be empty, in which case nothing was cached yet.
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std::vector<content_t> contents;
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private:
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// Whether day and night lighting differs
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bool m_day_night_differs = false;
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bool m_day_night_differs_expired = true;
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/*
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- On the server, this is used for telling whether the
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block has been modified from the one on disk.
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@ -506,14 +525,12 @@ private:
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u32 m_modified_reason = MOD_REASON_INITIAL;
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/*
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When propagating sunlight and the above block doesn't exist,
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sunlight is assumed if this is false.
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In practice this is set to true if the block is completely
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undeground with nothing visible above the ground except
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caves.
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When block is removed from active blocks, this is set to gametime.
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Value BLOCK_TIMESTAMP_UNDEFINED=0xffffffff means there is no timestamp.
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*/
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bool is_underground = false;
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u32 m_timestamp = BLOCK_TIMESTAMP_UNDEFINED;
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// The on-disk (or to-be on-disk) timestamp value
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u32 m_disk_timestamp = BLOCK_TIMESTAMP_UNDEFINED;
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/*!
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* Each bit indicates if light spreading was finished
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@ -525,35 +542,24 @@ private:
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*/
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u16 m_lighting_complete = 0xFFFF;
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// Whether day and night lighting differs
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bool m_day_night_differs = false;
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bool m_day_night_differs_expired = true;
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// see isOrphan()
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bool m_orphan = false;
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// Whether mapgen has generated the content of this block (persisted)
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bool m_generated = false;
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/*
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When block is removed from active blocks, this is set to gametime.
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Value BLOCK_TIMESTAMP_UNDEFINED=0xffffffff means there is no timestamp.
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*/
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u32 m_timestamp = BLOCK_TIMESTAMP_UNDEFINED;
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// The on-disk (or to-be on-disk) timestamp value
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u32 m_disk_timestamp = BLOCK_TIMESTAMP_UNDEFINED;
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When propagating sunlight and the above block doesn't exist,
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sunlight is assumed if this is false.
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/*
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When the block is accessed, this is set to 0.
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Map will unload the block when this reaches a timeout.
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In practice this is set to true if the block is completely
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undeground with nothing visible above the ground except
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caves.
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*/
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float m_usage_timer = 0;
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bool is_underground = false;
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/*
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Reference count; currently used for determining if this block is in
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the list of blocks to be drawn.
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*/
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short m_refcount = 0;
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public:
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NodeMetadataList m_node_metadata;
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StaticObjectList m_static_objects;
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private:
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NodeTimerList m_node_timers;
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};
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