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Overview
Comment:Further performance improvements to mem6.c. (CVS 5482)
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SHA1: 4528f7b1cce2d009f1bf32bfb8eeaf3ce5531f41
User & Date: danielk1977 2008-07-25 16:07:01.000
Context
2008-07-25
16:39
Add an SQLITE_OMIT_LOCALTIME around the "utc" modifier in date/time functions. (CVS 5483) (check-in: 71486e93b2 user: drh tags: trunk)
16:07
Further performance improvements to mem6.c. (CVS 5482) (check-in: 4528f7b1cc user: danielk1977 tags: trunk)
15:39
Add the capability to track the maximum depth of the LALR(1) parser stack so that critical applications can check to see if they are getting close to limits. (CVS 5481) (check-in: ef0250f3dc user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
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 1.5 2008/07/25 10:40:19 danielk1977 Exp $
*/

#ifdef SQLITE_ENABLE_MEMSYS6

#include "sqliteInt.h"

/*








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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 1.6 2008/07/25 16:07:01 danielk1977 Exp $
*/

#ifdef SQLITE_ENABLE_MEMSYS6

#include "sqliteInt.h"

/*
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*/
#define SMALL_MALLOC_DEFAULT_THRESHOLD 256

/*
** Minimum size for a memory chunk.
*/
#define MIN_CHUNKSIZE (1<<16)




typedef struct Mem6Chunk Mem6Chunk;
typedef struct Mem6Link Mem6Link;

/*
** A minimum allocation is an instance of the following structure.








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*/
#define SMALL_MALLOC_DEFAULT_THRESHOLD 256

/*
** Minimum size for a memory chunk.
*/
#define MIN_CHUNKSIZE (1<<16)

#define LOG2_MINALLOC 4


typedef struct Mem6Chunk Mem6Chunk;
typedef struct Mem6Link Mem6Link;

/*
** A minimum allocation is an instance of the following structure.
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  int nAtom;       /* Smallest possible allocation in bytes */
  int nBlock;      /* Number of nAtom sized blocks in zPool */
  u8 *zPool;       /* Pointer to memory chunk from which allocations are made */
};

#define MEM6LINK(idx) ((Mem6Link *)(&pChunk->zPool[(idx)*pChunk->nAtom]))









/*
** Unlink the chunk at pChunk->aPool[i] from list it is currently
** on.  It should be found on pChunk->aiFreelist[iLogsize].
*/
static void memsys6Unlink(Mem6Chunk *pChunk, int i, int iLogsize){
  int next, prev;
  assert( i>=0 && i<pChunk->nBlock );
  assert( iLogsize>=0 && iLogsize<=LOGMAX );
  assert( (pChunk->aCtrl[i] & CTRL_LOGSIZE)==iLogsize );

  next = MEM6LINK(i)->next;
  prev = MEM6LINK(i)->prev;
  if( prev<0 ){
    pChunk->aiFreelist[iLogsize] = next;
  }else{








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  int nAtom;       /* Smallest possible allocation in bytes */
  int nBlock;      /* Number of nAtom sized blocks in zPool */
  u8 *zPool;       /* Pointer to memory chunk from which allocations are made */
};

#define MEM6LINK(idx) ((Mem6Link *)(&pChunk->zPool[(idx)*pChunk->nAtom]))

struct Mem6Global {
  int nMinAlloc;                  /* Minimum allowed allocation size */
  int nThreshold;                 /* Allocs larger than this go to malloc() */
  int nLogThreshold;              /* log2 of (nThreshold/nMinAlloc) */
  sqlite3_mutex *mutex;
  Mem6Chunk *pChunk;              /* Singly linked list of all memory chunks */
} mem6;

/*
** Unlink the chunk at pChunk->aPool[i] from list it is currently
** on.  It should be found on pChunk->aiFreelist[iLogsize].
*/
static void memsys6Unlink(Mem6Chunk *pChunk, int i, int iLogsize){
  int next, prev;
  assert( i>=0 && i<pChunk->nBlock );
  assert( iLogsize>=0 && iLogsize<=mem6.nLogThreshold );
  assert( (pChunk->aCtrl[i] & CTRL_LOGSIZE)==iLogsize );

  next = MEM6LINK(i)->next;
  prev = MEM6LINK(i)->prev;
  if( prev<0 ){
    pChunk->aiFreelist[iLogsize] = next;
  }else{
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/*
** Link the chunk at mem5.aPool[i] so that is on the iLogsize
** free list.
*/
static void memsys6Link(Mem6Chunk *pChunk, int i, int iLogsize){
  int x;
  assert( i>=0 && i<pChunk->nBlock );
  assert( iLogsize>=0 && iLogsize<=LOGMAX );
  assert( (pChunk->aCtrl[i] & CTRL_LOGSIZE)==iLogsize );

  x = MEM6LINK(i)->next = pChunk->aiFreelist[iLogsize];
  MEM6LINK(i)->prev = -1;
  if( x>=0 ){
    assert( x<pChunk->nBlock );
    MEM6LINK(x)->prev = i;
  }
  pChunk->aiFreelist[iLogsize] = i;
}


/*
** Find the first entry on the freelist iLogsize.  Unlink that
** entry and return its index. 
*/
static int memsys6UnlinkFirst(Mem6Chunk *pChunk, int iLogsize){
  int i;
  int iFirst;

  assert( iLogsize>=0 && iLogsize<=LOGMAX );
  i = iFirst = pChunk->aiFreelist[iLogsize];
  assert( iFirst>=0 );
  while( i>0 ){
    if( i<iFirst ) iFirst = i;

    i = MEM6LINK(i)->next;






















  }
  memsys6Unlink(pChunk, iFirst, iLogsize);

  return iFirst;

}

/*
** Allocate and return a block of nByte bytes from chunk pChunk. If the
** allocation request cannot be satisfied, return 0.
*/
static void *chunkMalloc(Mem6Chunk *pChunk, int nByte){
  int i;           /* Index of a mem5.aPool[] slot */
  int iBin;        /* Index into mem5.aiFreelist[] */
  int iFullSz;     /* Size of allocation rounded up to power of 2 */
  int iLogsize;    /* Log2 of iFullSz/POW2_MIN */

  /* Round nByte up to the next valid power of two */
  if( nByte>(pChunk->nBlock*pChunk->nAtom) ) return 0;
  for(iFullSz=pChunk->nAtom, iLogsize=0; iFullSz<nByte; iFullSz *= 2, iLogsize++){}

  /* Make sure mem5.aiFreelist[iLogsize] contains at least one free
  ** block.  If not, then split a block of the next larger power of
  ** two in order to create a new free block of size iLogsize.
  */
  for(iBin=iLogsize; pChunk->aiFreelist[iBin]<0 && iBin<=LOGMAX; iBin++){}
  if( iBin>LOGMAX ) return 0;
  i = memsys6UnlinkFirst(pChunk, iBin);
  while( iBin>iLogsize ){
    int newSize;

    iBin--;
    newSize = 1 << iBin;
    pChunk->aCtrl[i+newSize] = CTRL_FREE | iBin;
    memsys6Link(pChunk, i+newSize, iBin);
  }
  pChunk->aCtrl[i] = iLogsize;









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/*
** Link the chunk at mem5.aPool[i] so that is on the iLogsize
** free list.
*/
static void memsys6Link(Mem6Chunk *pChunk, int i, int iLogsize){
  int x;
  assert( i>=0 && i<pChunk->nBlock );
  assert( iLogsize>=0 && iLogsize<=mem6.nLogThreshold );
  assert( (pChunk->aCtrl[i] & CTRL_LOGSIZE)==iLogsize );

  x = MEM6LINK(i)->next = pChunk->aiFreelist[iLogsize];
  MEM6LINK(i)->prev = -1;
  if( x>=0 ){
    assert( x<pChunk->nBlock );
    MEM6LINK(x)->prev = i;
  }
  pChunk->aiFreelist[iLogsize] = i;
}


/*
** Find the first entry on the freelist iLogsize.  Unlink that
** entry and return its index. 
*/
static int memsys6UnlinkFirst(Mem6Chunk *pChunk, int iLogsize){
  int i;
  int iFirst;

  assert( iLogsize>=0 && iLogsize<=mem6.nLogThreshold );
  i = iFirst = pChunk->aiFreelist[iLogsize];
  assert( iFirst>=0 );
  memsys6Unlink(pChunk, iFirst, iLogsize);
  return iFirst;
}

static int roundupLog2(int n){
  static const char LogTable256[256] = {
    0,                                                    /* 1 */
    1,                                                    /* 2 */
    2, 2,                                                 /* 3..4 */
    3, 3, 3, 3,                                           /* 5..8 */
    4, 4, 4, 4, 4, 4, 4, 4,                               /* 9..16 */
    5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,       /* 17..32 */
    6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
    6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,       /* 33..64 */
    7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
    7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
    7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
    7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,       /* 65..128 */
    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,       /* 129..256 */
  };

  assert(n<=(1<<16) && n>0);
  if( n<=256 ) return LogTable256[n-1];
  return LogTable256[(n>>8) - ((n&0xFF)?0:1)] + 8;
}

/*
** Allocate and return a block of (pChunk->nAtom << iLogsize) bytes from chunk
** pChunk. If the allocation request cannot be satisfied, return 0.
*/
static void *chunkMalloc(Mem6Chunk *pChunk, int iLogsize){
  int i;           /* Index of a mem5.aPool[] slot */
  int iBin;        /* Index into mem5.aiFreelist[] */







  /* Make sure mem5.aiFreelist[iLogsize] contains at least one free
  ** block.  If not, then split a block of the next larger power of
  ** two in order to create a new free block of size iLogsize.
  */
  for(iBin=iLogsize; pChunk->aiFreelist[iBin]<0 && iBin<=mem6.nLogThreshold; iBin++){}
  if( iBin>mem6.nLogThreshold ) return 0;
  i = memsys6UnlinkFirst(pChunk, iBin);
  while( iBin>iLogsize ){
    int newSize;

    iBin--;
    newSize = 1 << iBin;
    pChunk->aCtrl[i+newSize] = CTRL_FREE | iBin;
    memsys6Link(pChunk, i+newSize, iBin);
  }
  pChunk->aCtrl[i] = iLogsize;
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  size = 1<<iLogsize;
  assert( iBlock+size-1<pChunk->nBlock );

  pChunk->aCtrl[iBlock] |= CTRL_FREE;
  pChunk->aCtrl[iBlock+size-1] |= CTRL_FREE;

  pChunk->aCtrl[iBlock] = CTRL_FREE | iLogsize;
  while( iLogsize<LOGMAX ){
    int iBuddy;
    if( (iBlock>>iLogsize) & 1 ){
      iBuddy = iBlock - size;
    }else{
      iBuddy = iBlock + size;
    }
    assert( iBuddy>=0 );








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  size = 1<<iLogsize;
  assert( iBlock+size-1<pChunk->nBlock );

  pChunk->aCtrl[iBlock] |= CTRL_FREE;
  pChunk->aCtrl[iBlock+size-1] |= CTRL_FREE;

  pChunk->aCtrl[iBlock] = CTRL_FREE | iLogsize;
  while( iLogsize<mem6.nLogThreshold ){
    int iBuddy;
    if( (iBlock>>iLogsize) & 1 ){
      iBuddy = iBlock - size;
    }else{
      iBuddy = iBlock + size;
    }
    assert( iBuddy>=0 );
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  memset(pChunk, 0, sizeof(Mem6Chunk));
  pChunk->nAtom = nMinAlloc;
  pChunk->nBlock = ((nChunk-sizeof(Mem6Chunk)) / (pChunk->nAtom+sizeof(u8)));

  pChunk->zPool = (u8 *)&pChunk[1];
  pChunk->aCtrl = &pChunk->zPool[pChunk->nBlock*pChunk->nAtom];

  for(ii=0; ii<=LOGMAX; ii++){
    pChunk->aiFreelist[ii] = -1;
  }

  iOffset = 0;
  for(ii=LOGMAX; ii>=0; ii--){
    int nAlloc = (1<<ii);
    if( (iOffset+nAlloc)<=pChunk->nBlock ){
      pChunk->aCtrl[iOffset] = ii | CTRL_FREE;
      memsys6Link(pChunk, iOffset, ii);
      iOffset += nAlloc;
    }
    assert((iOffset+nAlloc)>pChunk->nBlock);
  }

  return pChunk;
}

struct Mem6Global {
  int nMinAlloc;                  /* Minimum allowed allocation size */
  int nThreshold;                 /* Allocs larger than this go to malloc() */
  sqlite3_mutex *mutex;
  Mem6Chunk *pChunk;              /* Singly linked list of all memory chunks */
} mem6;


static void mem6Enter(void){
  sqlite3_mutex_enter(mem6.mutex);
}

static void mem6Leave(void){
  sqlite3_mutex_leave(mem6.mutex);








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  memset(pChunk, 0, sizeof(Mem6Chunk));
  pChunk->nAtom = nMinAlloc;
  pChunk->nBlock = ((nChunk-sizeof(Mem6Chunk)) / (pChunk->nAtom+sizeof(u8)));

  pChunk->zPool = (u8 *)&pChunk[1];
  pChunk->aCtrl = &pChunk->zPool[pChunk->nBlock*pChunk->nAtom];

  for(ii=0; ii<=mem6.nLogThreshold; ii++){
    pChunk->aiFreelist[ii] = -1;
  }

  iOffset = 0;
  for(ii=mem6.nLogThreshold; ii>=0; ii--){
    int nAlloc = (1<<ii);
    while( (iOffset+nAlloc)<=pChunk->nBlock ){
      pChunk->aCtrl[iOffset] = ii | CTRL_FREE;
      memsys6Link(pChunk, iOffset, ii);
      iOffset += nAlloc;
    }

  }

  return pChunk;
}









static void mem6Enter(void){
  sqlite3_mutex_enter(mem6.mutex);
}

static void mem6Leave(void){
  sqlite3_mutex_leave(mem6.mutex);
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  Mem6Chunk *p;
  for(p=mem6.pChunk; p; p=p->pNext){
    iTotal = iTotal*2;
  }
  return iTotal;
}

/*
** The argument is a pointer that may or may not have been allocated from
** one of the Mem6Chunk objects managed within mem6. If it is, return
** a pointer to the owner chunk. If not, return 0.
*/
static Mem6Chunk *findChunk(u8 *p){
  Mem6Chunk *pChunk;
  for(pChunk=mem6.pChunk; pChunk; pChunk=pChunk->pNext){
    if( p>=pChunk->zPool && p<=&pChunk->zPool[pChunk->nBlock*pChunk->nAtom] ){
      return pChunk;
    }
  }
  return 0;
}

static void freeChunk(Mem6Chunk *pChunk){
  Mem6Chunk **pp = &mem6.pChunk;
  for( pp=&mem6.pChunk; *pp!=pChunk; pp = &(*pp)->pNext );
  *pp = (*pp)->pNext;
  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];








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  Mem6Chunk *p;
  for(p=mem6.pChunk; p; p=p->pNext){
    iTotal = iTotal*2;
  }
  return iTotal;
}
















static void freeChunk(Mem6Chunk *pChunk){
  Mem6Chunk **pp = &mem6.pChunk;
  for( pp=&mem6.pChunk; *pp!=pChunk; pp = &(*pp)->pNext );
  *pp = (*pp)->pNext;
  free(pChunk);
}

static void *memsys6Malloc(int nByte){
  Mem6Chunk *pChunk;
  void *p = 0;
  int nTotal = nByte+8;
  int iOffset = 0;


  if( nTotal>mem6.nThreshold ){
    p = malloc(nTotal);
  }else{
    int iLogsize = 0;
    if( nTotal>(1<<LOG2_MINALLOC) ){
      iLogsize = roundupLog2(nTotal) - LOG2_MINALLOC;
    }
    mem6Enter();
    for(pChunk=mem6.pChunk; pChunk; pChunk=pChunk->pNext){
      p = chunkMalloc(pChunk, iLogsize);
      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, iLogsize);
        assert(p);
      }
    }

    iOffset = ((u8*)p - (u8*)pChunk);

    mem6Leave();
  }

  if( !p ){
    return 0;
  }
  ((u32 *)p)[0] = iOffset;
  ((u32 *)p)[1] = nByte;
  return &((u32 *)p)[2];
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      memsys6Free(p);
    }
  }

  return p2;
}


static int memsys6Roundup(int n){
  int iFullSz;
  for(iFullSz=mem6.nMinAlloc; iFullSz<n; iFullSz *= 2);
  return iFullSz;



}

static int memsys6Init(void *pCtx){
  u8 bMemstat = sqlite3Config.bMemstat;
  mem6.nMinAlloc = 16;
  mem6.pChunk = 0;
  mem6.nThreshold = sqlite3Config.nSmall;
  if( mem6.nThreshold<=0 ){
    mem6.nThreshold = SMALL_MALLOC_DEFAULT_THRESHOLD;
  }

  if( !bMemstat ){
    mem6.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
  }

  return SQLITE_OK;
}

static void memsys6Shutdown(void *pCtx){
  memset(&mem6, 0, sizeof(mem6));
}









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<








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      memsys6Free(p);
    }
  }

  return p2;
}


static int memsys6Roundup(int n){

  if( n>mem6.nThreshold ){
    return n;
  }else{
    return (1<<roundupLog2(n));
  }
}

static int memsys6Init(void *pCtx){
  u8 bMemstat = sqlite3Config.bMemstat;
  mem6.nMinAlloc = (1 << LOG2_MINALLOC);
  mem6.pChunk = 0;
  mem6.nThreshold = sqlite3Config.nSmall;
  if( mem6.nThreshold<=0 ){
    mem6.nThreshold = SMALL_MALLOC_DEFAULT_THRESHOLD;
  }
  mem6.nLogThreshold = roundupLog2(mem6.nThreshold) - LOG2_MINALLOC;
  if( !bMemstat ){
    mem6.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
  }

  return SQLITE_OK;
}

static void memsys6Shutdown(void *pCtx){
  memset(&mem6, 0, sizeof(mem6));
}
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