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author | Jason Evans <jasone@canonware.com> | 2017-02-08 18:30:44 (GMT) |
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committer | Jason Evans <jasone@canonware.com> | 2017-02-09 02:50:03 (GMT) |
commit | de8a68e85304848189643fb48100c18aa9d60e32 (patch) | |
tree | 501e17ec14e3f73068711b8e19c470cc56c50b80 | |
parent | 5f118307543b128e1ad6298ec2ab1acd71140095 (diff) | |
download | jemalloc-de8a68e85304848189643fb48100c18aa9d60e32.zip jemalloc-de8a68e85304848189643fb48100c18aa9d60e32.tar.gz jemalloc-de8a68e85304848189643fb48100c18aa9d60e32.tar.bz2 |
Enhance spin_adaptive() to yield after several iterations.
This avoids worst case behavior if e.g. another thread is preempted
while owning the resource the spinning thread is waiting for.
-rw-r--r-- | Makefile.in | 1 | ||||
-rw-r--r-- | include/jemalloc/internal/spin_inlines.h | 17 | ||||
-rw-r--r-- | test/unit/spin.c | 16 |
3 files changed, 28 insertions, 6 deletions
diff --git a/Makefile.in b/Makefile.in index acd31f7..23056f7 100644 --- a/Makefile.in +++ b/Makefile.in @@ -189,6 +189,7 @@ TESTS_UNIT := \ $(srcroot)test/unit/size_classes.c \ $(srcroot)test/unit/slab.c \ $(srcroot)test/unit/smoothstep.c \ + $(srcroot)test/unit/spin.c \ $(srcroot)test/unit/stats.c \ $(srcroot)test/unit/stats_print.c \ $(srcroot)test/unit/ticker.c \ diff --git a/include/jemalloc/internal/spin_inlines.h b/include/jemalloc/internal/spin_inlines.h index 03beead..1657326 100644 --- a/include/jemalloc/internal/spin_inlines.h +++ b/include/jemalloc/internal/spin_inlines.h @@ -8,14 +8,19 @@ void spin_adaptive(spin_t *spin); #if (defined(JEMALLOC_ENABLE_INLINE) || defined(JEMALLOC_SPIN_C_)) JEMALLOC_INLINE void spin_adaptive(spin_t *spin) { - volatile uint64_t i; + volatile uint32_t i; - for (i = 0; i < (KQU(1) << spin->iteration); i++) { - CPU_SPINWAIT; - } - - if (spin->iteration < 63) { + if (spin->iteration < 5) { + for (i = 0; i < (1U << spin->iteration); i++) { + CPU_SPINWAIT; + } spin->iteration++; + } else { +#ifdef _WIN32 + SwitchToThread(); +#else + sched_yield(); +#endif } } diff --git a/test/unit/spin.c b/test/unit/spin.c new file mode 100644 index 0000000..bd368b3 --- /dev/null +++ b/test/unit/spin.c @@ -0,0 +1,16 @@ +#include "test/jemalloc_test.h" + +TEST_BEGIN(test_spin) { + spin_t spinner = SPIN_INITIALIZER; + + for (unsigned i = 0; i < 100; i++) { + spin_adaptive(&spinner); + } +} +TEST_END + +int +main(void) { + return test( + test_spin); +} |