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Overview
| Comment: | Speed up the xFree() method of the mem6.c allocator by storing the offset from the pointer to the start of its chunk in a header field. (CVS 5475) |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
0de54891d4901dec929459d27004efe8 |
| User & Date: | danielk1977 2008-07-25 10:40:19 |
Context
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2008-07-25
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| 12:39 | Fix a build problem on tclsqlite in Makefile.in. (CVS 5476) (check-in: e7a60480 user: drh tags: trunk) | |
| 10:40 | Speed up the xFree() method of the mem6.c allocator by storing the offset from the pointer to the start of its chunk in a header field. (CVS 5475) (check-in: 0de54891 user: danielk1977 tags: trunk) | |
| 09:24 | Change mem6.c to use the malloc() and free() functions directly, instead of going via another sqlite3_mem_methods structure. (CVS 5474) (check-in: cfa65e23 user: danielk1977 tags: trunk) | |
Changes
Changes to src/mem6.c.
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** the same as that used by mem5.c. ** ** This strategy is designed to prevent the default memory allocation ** system (usually the system malloc) from suffering from heap ** fragmentation. On some systems, heap fragmentation can cause a ** significant real-time slowdown. ** ** $Id: mem6.c,v 1.4 2008/07/25 09:24:13 danielk1977 Exp $ */ #ifdef SQLITE_ENABLE_MEMSYS6 #include "sqliteInt.h" /* ................................................................................ free(pChunk); } static void *memsys6Malloc(int nByte){ Mem6Chunk *pChunk; void *p = 0; int nTotal = nByte+8; mem6Enter(); if( nTotal>mem6.nThreshold ){ p = malloc(nTotal); }else{ for(pChunk=mem6.pChunk; !p && pChunk; pChunk=pChunk->pNext){ p = chunkMalloc(pChunk, nTotal); } if( !p ){ int iSize = nextChunkSize(); p = malloc(iSize); if( p ){ pChunk = chunkInit((u8 *)p, iSize, mem6.nMinAlloc); pChunk->pNext = mem6.pChunk; mem6.pChunk = pChunk; p = chunkMalloc(pChunk, nTotal); assert(p); } } } mem6Leave(); ((sqlite3_int64 *)p)[0] = nByte; return &((sqlite3_int64 *)p)[1]; } static int memsys6Size(void *pPrior){ sqlite3_int64 *p; if( pPrior==0 ) return 0; p = (sqlite3_int64*)pPrior; p--; return p[0]; } static void memsys6Free(void *pPrior){ Mem6Chunk *pChunk; void *p = &((sqlite3_int64 *)pPrior)[-1]; mem6Enter(); pChunk = findChunk(p); if( pChunk ){ chunkFree(pChunk, p); if( chunkIsEmpty(pChunk) ){ freeChunk(pChunk); } }else{ free(p); } mem6Leave(); } static void *memsys6Realloc(void *p, int nByte){ void *p2; if( p && nByte<=memsys6Size(p) ){ p2 = p; |
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** the same as that used by mem5.c. ** ** This strategy is designed to prevent the default memory allocation ** system (usually the system malloc) from suffering from heap ** fragmentation. On some systems, heap fragmentation can cause a ** significant real-time slowdown. ** ** $Id: mem6.c,v 1.5 2008/07/25 10:40:19 danielk1977 Exp $ */ #ifdef SQLITE_ENABLE_MEMSYS6 #include "sqliteInt.h" /* ................................................................................ free(pChunk); } static void *memsys6Malloc(int nByte){ Mem6Chunk *pChunk; void *p = 0; int nTotal = nByte+8; int iOffset = 0; mem6Enter(); if( nTotal>mem6.nThreshold ){ p = malloc(nTotal); }else{ for(pChunk=mem6.pChunk; pChunk; pChunk=pChunk->pNext){ p = chunkMalloc(pChunk, nTotal); if( p ){ break; } } if( !p ){ int iSize = nextChunkSize(); p = malloc(iSize); if( p ){ pChunk = chunkInit((u8 *)p, iSize, mem6.nMinAlloc); pChunk->pNext = mem6.pChunk; mem6.pChunk = pChunk; p = chunkMalloc(pChunk, nTotal); assert(p); } } iOffset = ((u8*)p - (u8*)pChunk); } mem6Leave(); if( !p ){ return 0; } ((u32 *)p)[0] = iOffset; ((u32 *)p)[1] = nByte; return &((u32 *)p)[2]; } static int memsys6Size(void *pPrior){ if( pPrior==0 ) return 0; return ((u32*)pPrior)[-1]; } static void memsys6Free(void *pPrior){ int iSlot; void *p = &((u32 *)pPrior)[-2]; iSlot = ((u32 *)p)[0]; if( iSlot ){ mem6Enter(); Mem6Chunk *pChunk = (Mem6Chunk *)(&((u8 *)p)[-1 * iSlot]); chunkFree(pChunk, p); if( chunkIsEmpty(pChunk) ){ freeChunk(pChunk); } mem6Leave(); }else{ free(p); } } static void *memsys6Realloc(void *p, int nByte){ void *p2; if( p && nByte<=memsys6Size(p) ){ p2 = p; |