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| author | Rainer Gerhards <rgerhards@adiscon.com> | 2013-10-26 13:09:59 +0200 |
|---|---|---|
| committer | Rainer Gerhards <rgerhards@adiscon.com> | 2013-10-26 13:09:59 +0200 |
| commit | a000bd661e0459524bd146a803e17df813350d92 (patch) | |
| tree | f737c83b8d532490590011fef17f4220157e2b60 | |
| parent | 244e4571849aef4ea0c26c398ba056ea7d641592 (diff) | |
| download | rsyslog-a000bd661e0459524bd146a803e17df813350d92.tar.gz rsyslog-a000bd661e0459524bd146a803e17df813350d92.tar.bz2 rsyslog-a000bd661e0459524bd146a803e17df813350d92.zip | |
slight performance optimization if GCC is used
We give branch prediction hints for the frequent RETiRet macro which is
used for error handling. Some slight performance gain is to be expected
from that.
| -rw-r--r-- | ChangeLog | 4 | ||||
| -rw-r--r-- | configure.ac | 8 | ||||
| -rw-r--r-- | runtime/rsyslog.h | 7 |
3 files changed, 18 insertions, 1 deletions
@@ -1,5 +1,9 @@ --------------------------------------------------------------------------- Version 7.5.6 [devel] 2013-10-?? +- slight performance optimization if GCC is used + We give branch prediction hints for the frequent RETiRet macro which is + used for error handling. Some slight performance gain is to be expected + from that. - removed global variable support The original idea was not well thought out and global variables, as implemented, worked far different from what anybody would expect. As diff --git a/configure.ac b/configure.ac index 2f23147b..ebf35190 100644 --- a/configure.ac +++ b/configure.ac @@ -153,6 +153,14 @@ AC_TRY_COMPILE([ AC_MSG_RESULT(no; defined as 64) ) +# Check for __builtin_expect() +AC_MSG_CHECKING([for __builtin_expect()]) +AC_LINK_IFELSE([AC_LANG_PROGRAM(, return __builtin_expect(main != 0, 1))], + [AC_DEFINE(HAVE_BUILTIN_EXPECT, 1, + Define to 1 if compiler supports __builtin_expect) + AC_MSG_RESULT([yes])], + [AC_MSG_RESULT([no])]) + # check for availability of atomic operations RS_ATOMIC_OPERATIONS RS_ATOMIC_OPERATIONS_64BIT diff --git a/runtime/rsyslog.h b/runtime/rsyslog.h index 71849bec..85381b8d 100644 --- a/runtime/rsyslog.h +++ b/runtime/rsyslog.h @@ -445,7 +445,12 @@ enum rsRetVal_ /** return value. All methods return this if not specified oth * Be sure to call the to-be-returned variable always "iRet" and * the function finalizer always "finalize_it". */ -#define CHKiRet(code) if((iRet = code) != RS_RET_OK) goto finalize_it +#if HAVE_BUILTIN_EXCEPT +# define CHKiRet(code) if(__builtin_expect(((iRet = code) != RS_RET_OK), 0)) goto finalize_it +#else +# define CHKiRet(code) if((iRet = code) != RS_RET_OK) goto finalize_it +#endif + /* macro below is to be used if we need our own handling, eg for cleanup */ #define CHKiRet_Hdlr(code) if((iRet = code) != RS_RET_OK) /* macro below is to handle failing malloc/calloc/strdup... which we almost always handle in the same way... */ |