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Overview
| Comment: | Performance improvements on memory copies inside of btree by moving 2 bytes at a time instead of just 1 byte at a time. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
897f56a158ebe62758c9998e4941ae04 |
| User & Date: | drh 2011-06-03 23:28:33 |
References
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2011-06-06
| ||
| 13:38 | Add assert() statements to verify that u16 pointers associated with the enhancement in [897f56a158] are always 2-byte aligned. check-in: 98ccfa93 user: drh tags: trunk | |
Context
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2011-06-04
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| 01:43 | Performance improvement to the btree search routine. check-in: 65db822f user: drh tags: trunk | |
|
2011-06-03
| ||
| 23:28 | Performance improvements on memory copies inside of btree by moving 2 bytes at a time instead of just 1 byte at a time. check-in: 897f56a1 user: drh tags: trunk | |
| 21:34 | Performance enhancement to the blob-literal tokenizer. check-in: 61aa2031 user: drh tags: trunk | |
Changes
Changes to src/btree.c.
5418 5418 rc = freeSpace(pPage, pc, sz); 5419 5419 if( rc ){ 5420 5420 *pRC = rc; 5421 5421 return; 5422 5422 } 5423 5423 endPtr = &data[pPage->cellOffset + 2*pPage->nCell - 2]; 5424 5424 while( ptr<endPtr ){ 5425 - ptr[0] = ptr[2]; 5426 - ptr[1] = ptr[3]; 5425 + *(u16*)ptr = *(u16*)&ptr[2]; 5427 5426 ptr += 2; 5428 5427 } 5429 5428 pPage->nCell--; 5430 5429 put2byte(&data[hdr+3], pPage->nCell); 5431 5430 pPage->nFree += 2; 5432 5431 } 5433 5432 ................................................................................ 5460 5459 int idx = 0; /* Where to write new cell content in data[] */ 5461 5460 int j; /* Loop counter */ 5462 5461 int end; /* First byte past the last cell pointer in data[] */ 5463 5462 int ins; /* Index in data[] where new cell pointer is inserted */ 5464 5463 int cellOffset; /* Address of first cell pointer in data[] */ 5465 5464 u8 *data; /* The content of the whole page */ 5466 5465 u8 *ptr; /* Used for moving information around in data[] */ 5466 + u8 *endPtr; /* End of the loop */ 5467 5467 5468 5468 int nSkip = (iChild ? 4 : 0); 5469 5469 5470 5470 if( *pRC ) return; 5471 5471 5472 5472 assert( i>=0 && i<=pPage->nCell+pPage->nOverflow ); 5473 5473 assert( pPage->nCell<=MX_CELL(pPage->pBt) && MX_CELL(pPage->pBt)<=10921 ); ................................................................................ 5510 5510 assert( idx+sz <= (int)pPage->pBt->usableSize ); 5511 5511 pPage->nCell++; 5512 5512 pPage->nFree -= (u16)(2 + sz); 5513 5513 memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip); 5514 5514 if( iChild ){ 5515 5515 put4byte(&data[idx], iChild); 5516 5516 } 5517 - for(j=end, ptr=&data[j]; j>ins; j-=2, ptr-=2){ 5518 - ptr[0] = ptr[-2]; 5519 - ptr[1] = ptr[-1]; 5517 + ptr = &data[end]; 5518 + endPtr = &data[ins]; 5519 + while( ptr>endPtr ){ 5520 + *(u16*)ptr = *(u16*)&ptr[-2]; 5521 + ptr -= 2; 5520 5522 } 5521 5523 put2byte(&data[ins], idx); 5522 5524 put2byte(&data[pPage->hdrOffset+3], pPage->nCell); 5523 5525 #ifndef SQLITE_OMIT_AUTOVACUUM 5524 5526 if( pPage->pBt->autoVacuum ){ 5525 5527 /* The cell may contain a pointer to an overflow page. If so, write 5526 5528 ** the entry for the overflow page into the pointer map. ................................................................................ 5557 5559 /* Check that the page has just been zeroed by zeroPage() */ 5558 5560 assert( pPage->nCell==0 ); 5559 5561 assert( get2byteNotZero(&data[hdr+5])==nUsable ); 5560 5562 5561 5563 pCellptr = &data[pPage->cellOffset + nCell*2]; 5562 5564 cellbody = nUsable; 5563 5565 for(i=nCell-1; i>=0; i--){ 5566 + u16 sz = aSize[i]; 5564 5567 pCellptr -= 2; 5565 - cellbody -= aSize[i]; 5568 + cellbody -= sz; 5566 5569 put2byte(pCellptr, cellbody); 5567 - memcpy(&data[cellbody], apCell[i], aSize[i]); 5570 + memcpy(&data[cellbody], apCell[i], sz); 5568 5571 } 5569 5572 put2byte(&data[hdr+3], nCell); 5570 5573 put2byte(&data[hdr+5], cellbody); 5571 5574 pPage->nFree -= (nCell*2 + nUsable - cellbody); 5572 5575 pPage->nCell = (u16)nCell; 5573 5576 } 5574 5577