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Simplification to the insertCell() routine in btree.c, resulting in a

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performance boost and a very small size decrease.  It turns out that the
extra work involved in sometimes avoiding an memcpy() of the first four bytes
of a record takes more time than just unconditionally copying those
four bytes.

FossilOrigin-Name: 66de15580d3c289601e67debfe1edee286f4db5f
This commit is contained in:
drh
2014-10-11 17:22:55 +00:00
parent 8683e08676
commit d6176c4131
3 changed files with 9 additions and 15 deletions
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12
manifest
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@@ -1,5 +1,5 @@
C Require\sthe\sSQLITE_ENABLE_RTREE\scompile-time\soption\sin\sspeedtest1.c\sin\sorder\nto\senable\sthe\sR-Tree\stests. C Simplification\sto\sthe\sinsertCell()\sroutine\sin\sbtree.c,\sresulting\sin\sa\nperformance\sboost\sand\sa\svery\ssmall\ssize\sdecrease.\s\sIt\sturns\sout\sthat\sthe\nextra\swork\sinvolved\sin\ssometimes\savoiding\san\smemcpy()\sof\sthe\sfirst\sfour\sbytes\nof\sa\srecord\stakes\smore\stime\sthan\sjust\sunconditionally\scopying\sthose\nfour\sbytes.
D 2014-10-11T10:52:54.590 D 2014-10-11T17:22:55.486
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in cf57f673d77606ab0f2d9627ca52a9ba1464146a F Makefile.in cf57f673d77606ab0f2d9627ca52a9ba1464146a
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -172,7 +172,7 @@ F src/auth.c d8abcde53426275dab6243b441256fcd8ccbebb2
F src/backup.c a31809c65623cc41849b94d368917f8bb66e6a7e F src/backup.c a31809c65623cc41849b94d368917f8bb66e6a7e
F src/bitvec.c 19a4ba637bd85f8f63fc8c9bae5ade9fb05ec1cb F src/bitvec.c 19a4ba637bd85f8f63fc8c9bae5ade9fb05ec1cb
F src/btmutex.c 49ca66250c7dfa844a4d4cb8272b87420d27d3a5 F src/btmutex.c 49ca66250c7dfa844a4d4cb8272b87420d27d3a5
F src/btree.c fa00618117fb6bb46c243452c56997c0d22d4fc9 F src/btree.c 5c0b78c49d00da49a0e8e3d2738900a431df7fca
F src/btree.h a79aa6a71e7f1055f01052b7f821bd1c2dce95c8 F src/btree.h a79aa6a71e7f1055f01052b7f821bd1c2dce95c8
F src/btreeInt.h 1bd7957161a1346a914f1f09231610e777a8e58d F src/btreeInt.h 1bd7957161a1346a914f1f09231610e777a8e58d
F src/build.c 9e5205db9a0c8a1a4ce7379d60a2a34cb0b7339c F src/build.c 9e5205db9a0c8a1a4ce7379d60a2a34cb0b7339c
@@ -1204,7 +1204,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
P 7a32fdfd4be2138c0ab00f3dc6f54a70e4e07be4 P 5d29a033b0f17b0fd74656b28a8367a9a9067f81
R 4281e286fbeeaa18c9716d9bb0cdd63c R 8d2ebada6cfcd93628f86065b0703bad
U drh U drh
Z 50870d5e316ccf74380338fbaf696334 Z b915e33ee9cbdc5e832f0d58216a79da

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@@ -1 +1 @@
5d29a033b0f17b0fd74656b28a8367a9a9067f81 66de15580d3c289601e67debfe1edee286f4db5f

10
src/btree.c
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@@ -5845,11 +5845,6 @@ static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){
** in pTemp or the original pCell) and also record its index. ** in pTemp or the original pCell) and also record its index.
** Allocating a new entry in pPage->aCell[] implies that ** Allocating a new entry in pPage->aCell[] implies that
** pPage->nOverflow is incremented. ** pPage->nOverflow is incremented.
**
** If nSkip is non-zero, then do not copy the first nSkip bytes of the
** cell. The caller will overwrite them after this function returns. If
** nSkip is non-zero, then pCell may not point to an invalid memory location
** (but pCell+nSkip is always valid).
*/ */
static void insertCell( static void insertCell(
MemPage *pPage, /* Page into which we are copying */ MemPage *pPage, /* Page into which we are copying */
@@ -5866,7 +5861,6 @@ static void insertCell(
int ins; /* Index in data[] where new cell pointer is inserted */ int ins; /* Index in data[] where new cell pointer is inserted */
int cellOffset; /* Address of first cell pointer in data[] */ int cellOffset; /* Address of first cell pointer in data[] */
u8 *data; /* The content of the whole page */ u8 *data; /* The content of the whole page */
int nSkip = (iChild ? 4 : 0);
if( *pRC ) return; if( *pRC ) return;
@@ -5884,7 +5878,7 @@ static void insertCell(
assert( sz==cellSizePtr(pPage, pCell) || (sz==8 && iChild>0) ); assert( sz==cellSizePtr(pPage, pCell) || (sz==8 && iChild>0) );
if( pPage->nOverflow || sz+2>pPage->nFree ){ if( pPage->nOverflow || sz+2>pPage->nFree ){
if( pTemp ){ if( pTemp ){
memcpy(pTemp+nSkip, pCell+nSkip, sz-nSkip); memcpy(pTemp, pCell, sz);
pCell = pTemp; pCell = pTemp;
} }
if( iChild ){ if( iChild ){
@@ -5913,7 +5907,7 @@ static void insertCell(
assert( idx+sz <= (int)pPage->pBt->usableSize ); assert( idx+sz <= (int)pPage->pBt->usableSize );
pPage->nCell++; pPage->nCell++;
pPage->nFree -= (u16)(2 + sz); pPage->nFree -= (u16)(2 + sz);
memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip); memcpy(&data[idx], pCell, sz);
if( iChild ){ if( iChild ){
put4byte(&data[idx], iChild); put4byte(&data[idx], iChild);
} }