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Optimize res_find().

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When the device name is provided, we can simply run strncmp() for each
line to quickly skip unrelated ones, that is much faster than sscanf()
and only then strcmp().

MFC after:	2 weeks
This commit is contained in:
Alexander Motin 2021-08-08 21:34:33 -04:00
parent d8789cd0ae
commit 696fca3fd4
1 changed files with 6 additions and 2 deletions
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8
sys/kern/subr_hints.c
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@ -127,7 +127,7 @@ res_find(char **hintp_cookie, int *line, int *startln,
const char **ret_name, int *ret_namelen, int *ret_unit,
const char **ret_resname, int *ret_resnamelen, const char **ret_value)
{
int fbacklvl = FBACK_MDENV, i = 0, n = 0;
int fbacklvl = FBACK_MDENV, i = 0, n = 0, namelen;
char r_name[32];
int r_unit;
char r_resname[32];
@ -229,12 +229,16 @@ res_find(char **hintp_cookie, int *line, int *startln,
i = 0;
}
if (name)
namelen = strlen(name);
cp = hintp;
while (cp) {
(*line)++;
if (strncmp(cp, "hint.", 5) != 0)
goto nexthint;
n = sscanf(cp, "hint.%32[^.].%d.%32[^=]=%127s", r_name, &r_unit,
if (name && strncmp(cp + 5, name, namelen) != 0)
goto nexthint;
n = sscanf(cp + 5, "%32[^.].%d.%32[^=]=%127s", r_name, &r_unit,
r_resname, r_value);
if (n != 4) {
printf("CONFIG: invalid hint '%s'\n", cp);