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[OPTIM] halog: speed up fgets2-64 by about 10% 

This version uses more 64-bit lookups and two 32-bit lookups
to converge faster. This saves about 10% performance.
This commit is contained in:
Willy Tarreau 2010-05-05 12:22:08 +02:00
parent 2651ac3302
commit d2c142c7ee
1 changed files with 30 additions and 6 deletions
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36
contrib/halog/fgets2-64.c
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@ -62,7 +62,7 @@ static inline unsigned int has_zero64(unsigned long long x)
#define FGETS2_BUFSIZE (256*1024) #define FGETS2_BUFSIZE (256*1024)
const char *fgets2(FILE *stream) const char *fgets2(FILE *stream)
{ {
static char buffer[FGETS2_BUFSIZE + 5]; static char buffer[FGETS2_BUFSIZE + 9]; // +9 to have zeroes past the end
static char *end = buffer; static char *end = buffer;
static char *line = buffer; static char *line = buffer;
@ -72,15 +72,35 @@ const char *fgets2(FILE *stream)
next = line; next = line;
while (1) { while (1) {
/* this is a speed-up, we read 32 bits at once and check for an /* this is a speed-up, we read 64 bits at once and check for an
* LF character there. We stop if found then continue one at a * LF character there. We stop if found then continue one at a
* time. * time.
*/ */
while (next < end && (((unsigned long)next) & 7) && *next != '\n')
next++;
/* now next is multiple of 4 or equal to end */ if (next <= (end-12)) {
while (next <= (end-32)) { /* max 3 bytes tested here */
while ((((unsigned long)next) & 3) && *next != '\n')
next++;
/* maybe we have can skip 4 more bytes */
if ((((unsigned long)next) & 4) && !has_zero(*(unsigned int *)next ^ 0x0A0A0A0AU))
next += 4;
}
/* now next is multiple of 8 or equal to end */
while (next <= (end-68)) {
if (has_zero64(*(unsigned long long *)next ^ 0x0A0A0A0A0A0A0A0AULL))
break;
next += 8;
if (has_zero64(*(unsigned long long *)next ^ 0x0A0A0A0A0A0A0A0AULL))
break;
next += 8;
if (has_zero64(*(unsigned long long *)next ^ 0x0A0A0A0A0A0A0A0AULL))
break;
next += 8;
if (has_zero64(*(unsigned long long *)next ^ 0x0A0A0A0A0A0A0A0AULL))
break;
next += 8;
if (has_zero64(*(unsigned long long *)next ^ 0x0A0A0A0A0A0A0A0AULL)) if (has_zero64(*(unsigned long long *)next ^ 0x0A0A0A0A0A0A0A0AULL))
break; break;
next += 8; next += 8;
@ -95,6 +115,10 @@ const char *fgets2(FILE *stream)
next += 8; next += 8;
} }
/* maybe we can skip 4 more bytes */
if (!has_zero(*(unsigned int *)next ^ 0x0A0A0A0AU))
next += 4;
/* we finish if needed. Note that next might be slightly higher /* we finish if needed. Note that next might be slightly higher
* than end here because we might have gone past it above. * than end here because we might have gone past it above.
*/ */