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In the pager, cache a pointer to the first page on the freelist that does not

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need to be synced.  This makes a fetch of a page that is not in cache go a
lot faster when the cache is full.  This check-in also adds some performance
instrumentation to the OS layer. (CVS 842)

FossilOrigin-Name: 00f08fc0b5b6b9c5efbf15a62f9a1cc1cfa71283
This commit is contained in:
drh
2003-01-21 02:39:36 +00:00
parent e78e8284ad
commit 341eae8d35
4 changed files with 75 additions and 24 deletions
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35
src/os.c
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@@ -52,15 +52,32 @@
*/
#if 0
static int last_page = 0;
#define SEEK(X) last_page=(X)
#define TRACE1(X) fprintf(stderr,X)
#define TRACE2(X,Y) fprintf(stderr,X,Y)
#define TRACE3(X,Y,Z) fprintf(stderr,X,Y,Z)
__inline__ unsigned long long int hwtime(void){
unsigned long long int x;
__asm__("rdtsc\n\t"
"mov %%edx, %%ecx\n\t"
:"=A" (x));
return x;
}
static unsigned long long int g_start;
static unsigned int elapse;
#define TIMER_START g_start=hwtime()
#define TIMER_END elapse=hwtime()-g_start
#define SEEK(X) last_page=(X)
#define TRACE1(X) fprintf(stderr,X)
#define TRACE2(X,Y) fprintf(stderr,X,Y)
#define TRACE3(X,Y,Z) fprintf(stderr,X,Y,Z)
#define TRACE4(X,Y,Z,A) fprintf(stderr,X,Y,Z,A)
#define TRACE5(X,Y,Z,A,B) fprintf(stderr,X,Y,Z,A,B)
#else
#define TIMER_START
#define TIMER_END
#define SEEK(X)
#define TRACE1(X)
#define TRACE2(X,Y)
#define TRACE3(X,Y,Z)
#define TRACE4(X,Y,Z,A)
#define TRACE5(X,Y,Z,A,B)
#endif
@@ -664,8 +681,11 @@ int sqliteOsRead(OsFile *id, void *pBuf, int amt){
#if OS_UNIX
int got;
SimulateIOError(SQLITE_IOERR);
TRACE3("READ %-3d %d\n", id->fd, last_page);
TIMER_START;
got = read(id->fd, pBuf, amt);
TIMER_END;
TRACE4("READ %-3d %7d %d\n", id->fd, last_page, elapse);
SEEK(0);
/* if( got<0 ) got = 0; */
if( got==amt ){
return SQLITE_OK;
@@ -712,11 +732,14 @@ int sqliteOsWrite(OsFile *id, const void *pBuf, int amt){
#if OS_UNIX
int wrote = 0;
SimulateIOError(SQLITE_IOERR);
TRACE3("WRITE %-3d %d\n", id->fd, last_page);
TIMER_START;
while( amt>0 && (wrote = write(id->fd, pBuf, amt))>0 ){
amt -= wrote;
pBuf = &((char*)pBuf)[wrote];
}
TIMER_END;
TRACE4("WRITE %-3d %7d %d\n", id->fd, last_page, elapse);
SEEK(0);
if( amt>0 ){
return SQLITE_FULL;
}