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Stop providing branch prediction information

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The __builtin_expect() can be used to provide the compiler with branch
prediction information.  The Gcc manual says[1] on the subject:

    In general, you should prefer to use actual profile feedback for
    this (-fprofile-arcs), as programmers are notoriously bad at
    predicting how their programs actually perform.

Stop using __builtin_expect() and ISC_LIKELY() and ISC_UNLIKELY() macros
to provide the branch prediction information as the performance testing
shows that named performs better when the __builtin_expect() is not
being used.

1. https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005fexpect
This commit is contained in:
Ondřej Surý
2021-10-14 10:33:24 +02:00
parent 80fedf9231
commit e603983ec9
25 changed files with 114 additions and 180 deletions
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4
lib/isc/hmac.c
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@@ -31,7 +31,7 @@ isc_hmac_new(void) {
void
isc_hmac_free(isc_hmac_t *hmac) {
if (ISC_UNLIKELY(hmac == NULL)) {
if (hmac == NULL) {
return;
}
@@ -70,7 +70,7 @@ isc_result_t
isc_hmac_update(isc_hmac_t *hmac, const unsigned char *buf, const size_t len) {
REQUIRE(hmac != NULL);
if (ISC_UNLIKELY(buf == NULL || len == 0)) {
if (buf == NULL || len == 0) {
return (ISC_R_SUCCESS);
}