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| author | Kazunori Asayama <asayama@sm.sony.co.jp> | 2009-02-05 18:30:52 -0800 |
|---|---|---|
| committer | Yuji Mano <yuji.mano@am.sony.com> | 2009-02-11 11:02:53 -0800 |
| commit | 8076f490cd85ec2c7a17d05018e8c180fb5d1122 (patch) | |
| tree | d417a57e53748e9b584c8a05ae034e75a0b75636 | |
| parent | c5d91b1a18da4fbcb833809f163e9663c474cc9b (diff) | |
| download | mars-src-8076f490cd85ec2c7a17d05018e8c180fb5d1122.tar.gz | |
base: Cond wait hybrid
Add hybrid method to wait for condition on host side
The current implementation to wait for condition on host side has
significant performance loss and unexpected load of host CPU because
of frequent use of futex.
This patch adds short sched_yield loop before futex_wait to improve
performance and to reduce extra load in case that the condition
becomes satisfied soon after condition test fails.
Signed-off-by: Kazunori Asayama <asayama@sm.sony.co.jp>
Signed-off-by: Yuji Mano <yuji.mano@am.sony.com>
| -rw-r--r-- | base/src/host/lib/cond_cell.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/base/src/host/lib/cond_cell.c b/base/src/host/lib/cond_cell.c index fd9ede3..30015de 100644 --- a/base/src/host/lib/cond_cell.c +++ b/base/src/host/lib/cond_cell.c @@ -44,6 +44,8 @@ #include "mars/base.h" #include "mars/error.h" +#define SPIN_MAX 50 + #ifdef ENABLE_COND_WAIT_FUTEX #include <unistd.h> @@ -79,6 +81,7 @@ int mars_ea_cond_wait(uint64_t watch_point_ea, void *test_cond_param) { int ret; + int spin = 0; while (1) { uint32_t val = mars_ea_get_uint32(watch_point_ea); @@ -88,12 +91,17 @@ int mars_ea_cond_wait(uint64_t watch_point_ea, break; #ifdef ENABLE_COND_WAIT_FUTEX - ret = futex_wait(mars_ea_to_ptr(watch_point_ea), val); - if (ret != MARS_SUCCESS) - break; -#else - sched_yield(); + if (spin >= SPIN_MAX) { + ret = futex_wait(mars_ea_to_ptr(watch_point_ea), val); + if (ret != MARS_SUCCESS) + break; + } + else #endif + { + sched_yield(); + spin++; + } } return ret; |