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Overview
| Comment: | A much simpler fix is to simply change MEMSYS5 so that it takes any free block of the appropriate size (the first on the list of free blocks) rather than searching for the one with the smallest address. This is also faster than using the min-heap algorithm. Need to research to verify that the allocator still satisfies the Robson proof, however. |
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| SHA1: |
8191b512122c13d7fa61d8e5487652f1 |
| User & Date: | drh 2013-11-23 22:45:12 |
Context
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2013-11-24
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| 00:46 | The MEMSYS5 algorithm does not have to return the block with the lowest address. Any block of the appropriate size will do. Use the first block found on the freelist for the appropriate size for a performance improvement. check-in: 12e612e8 user: drh tags: trunk | |
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2013-11-23
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| 22:45 | A much simpler fix is to simply change MEMSYS5 so that it takes any free block of the appropriate size (the first on the list of free blocks) rather than searching for the one with the smallest address. This is also faster than using the min-heap algorithm. Need to research to verify that the allocator still satisfies the Robson proof, however. Closed-Leaf check-in: 8191b512 user: drh tags: memsys5-performance | |
| 21:29 | Add newlines at the end of some error messages in speedtest1. check-in: 6b98f0af user: drh tags: trunk | |
Changes
Changes to src/mem5.c.
210 210 } 211 211 212 212 /* 213 213 ** Find the first entry on the freelist iLogsize. Unlink that 214 214 ** entry and return its index. 215 215 */ 216 216 static int memsys5UnlinkFirst(int iLogsize){ 217 - int i; 218 217 int iFirst; 219 218 220 219 assert( iLogsize>=0 && iLogsize<=LOGMAX ); 221 - i = iFirst = mem5.aiFreelist[iLogsize]; 222 - assert( iFirst>=0 ); 223 - while( i>0 ){ 224 - if( i<iFirst ) iFirst = i; 225 - i = MEM5LINK(i)->next; 220 + iFirst = mem5.aiFreelist[iLogsize]; 221 +#if 0 222 + { 223 + int i = iFirst; 224 + assert( iFirst>=0 ); 225 + while( i>0 ){ 226 + if( i<iFirst ) iFirst = i; 227 + i = MEM5LINK(i)->next; 228 + } 226 229 } 230 +#endif 227 231 memsys5Unlink(iFirst, iLogsize); 228 232 return iFirst; 229 233 } 230 234 231 235 /* 232 236 ** Return a block of memory of at least nBytes in size. 233 237 ** Return NULL if unable. Return NULL if nBytes==0.