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| author | Wilco Dijkstra <wdijkstr@arm.com> | 2022-08-11 16:47:45 +0100 |
|---|---|---|
| committer | Wilco Dijkstra <wdijkstr@arm.com> | 2022-08-11 16:47:45 +0100 |
| commit | c51c483d2b8ae66fe31a12509aedae02a6982ced (patch) | |
| tree | c1da76a910cc6e015843c24b495c987237de916d | |
| parent | 11f09947f3066f5ff84fd15ef22b72b46eea97a8 (diff) | |
| download | glibc-c51c483d2b8ae66fe31a12509aedae02a6982ced.zip glibc-c51c483d2b8ae66fe31a12509aedae02a6982ced.tar.gz glibc-c51c483d2b8ae66fe31a12509aedae02a6982ced.tar.bz2 | |
libio: Improve performance of IO locks
Improve performance of recursive IO locks by adding a fast path for
the single-threaded case. To reduce the number of memory accesses for
locking/unlocking, only increment the recursion counter if the lock
is already taken.
On Neoverse V1, a microbenchmark with many small freads improved by
2.9x. Multithreaded performance improved by 2%.
Reviewed-by: Cristian RodrÃguez <crrodriguez@opensuse.org>
| -rw-r--r-- | sysdeps/nptl/stdio-lock.h | 28 |
1 files changed, 19 insertions, 9 deletions
diff --git a/sysdeps/nptl/stdio-lock.h b/sysdeps/nptl/stdio-lock.h index afa0b77..45823cd 100644 --- a/sysdeps/nptl/stdio-lock.h +++ b/sysdeps/nptl/stdio-lock.h @@ -37,12 +37,18 @@ typedef struct { int lock; int cnt; void *owner; } _IO_lock_t; #define _IO_lock_lock(_name) \ do { \ void *__self = THREAD_SELF; \ - if ((_name).owner != __self) \ + if (SINGLE_THREAD_P && (_name).owner == NULL) \ + { \ + (_name).lock = LLL_LOCK_INITIALIZER_LOCKED; \ + (_name).owner = __self; \ + } \ + else if ((_name).owner != __self) \ { \ lll_lock ((_name).lock, LLL_PRIVATE); \ - (_name).owner = __self; \ + (_name).owner = __self; \ } \ - ++(_name).cnt; \ + else \ + ++(_name).cnt; \ } while (0) #define _IO_lock_trylock(_name) \ @@ -52,10 +58,7 @@ typedef struct { int lock; int cnt; void *owner; } _IO_lock_t; if ((_name).owner != __self) \ { \ if (lll_trylock ((_name).lock) == 0) \ - { \ - (_name).owner = __self; \ - (_name).cnt = 1; \ - } \ + (_name).owner = __self; \ else \ __result = EBUSY; \ } \ @@ -66,11 +69,18 @@ typedef struct { int lock; int cnt; void *owner; } _IO_lock_t; #define _IO_lock_unlock(_name) \ do { \ - if (--(_name).cnt == 0) \ + if (SINGLE_THREAD_P && (_name).cnt == 0) \ + { \ + (_name).owner = NULL; \ + (_name).lock = 0; \ + } \ + else if ((_name).cnt == 0) \ { \ - (_name).owner = NULL; \ + (_name).owner = NULL; \ lll_unlock ((_name).lock, LLL_PRIVATE); \ } \ + else \ + --(_name).cnt; \ } while (0) |