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authorRickard Green <[email protected]>2016-06-20 15:51:25 +0200
committerRickard Green <[email protected]>2016-06-22 17:13:45 +0200
commitb71dde8bd94985f5953a1647802ac312a798fe69 (patch)
treed9aa5f8970daaff01d2e925e6fea7727ad233a77 /erts/emulator/sys/common
parent3b7a6ffddc819bf305353a593904cea9e932e7dc (diff)
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Improve accuracy of timeouts using premature timeouts
Improve accuracy of timeouts using a premature timeout then return to sleep with a shorter timeout just before requested timeout. This approach is only used on certain platforms where we know it improves the accuracy of the timeouts, e.g. MacOS X.
Diffstat (limited to 'erts/emulator/sys/common')
-rw-r--r--erts/emulator/sys/common/erl_poll.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/erts/emulator/sys/common/erl_poll.c b/erts/emulator/sys/common/erl_poll.c
index e394d84f73..b8a28bcc18 100644
--- a/erts/emulator/sys/common/erl_poll.c
+++ b/erts/emulator/sys/common/erl_poll.c
@@ -75,6 +75,7 @@
#include "erl_driver.h"
#include "erl_alloc.h"
#include "erl_msacc.h"
+#include "erl_misc_utils.h"
#if !defined(ERTS_POLL_USE_EPOLL) \
&& !defined(ERTS_POLL_USE_DEVPOLL) \
@@ -2132,16 +2133,19 @@ get_timeout(ErtsPollSet ps,
if (timeout > (ErtsMonotonicTime) INT_MAX)
timeout = (ErtsMonotonicTime) INT_MAX;
save_timeout_time += ERTS_MSEC_TO_MONOTONIC(timeout);
+ timeout -= ERTS_PREMATURE_TIMEOUT(timeout, 1000);
break;
case 1000000:
/* Round up to nearest even micro second */
timeout = ERTS_MONOTONIC_TO_USEC(diff_time - 1) + 1;
save_timeout_time += ERTS_USEC_TO_MONOTONIC(timeout);
+ timeout -= ERTS_PREMATURE_TIMEOUT(timeout, 1000*1000);
break;
case 1000000000:
/* Round up to nearest even nano second */
timeout = ERTS_MONOTONIC_TO_NSEC(diff_time - 1) + 1;
save_timeout_time += ERTS_NSEC_TO_MONOTONIC(timeout);
+ timeout -= ERTS_PREMATURE_TIMEOUT(timeout, 1000*1000*1000);
break;
default:
ERTS_INTERNAL_ERROR("Invalid resolution");
@@ -2452,7 +2456,15 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
}
#endif
- res = check_fd_events(ps, to, no_fds);
+ while (1) {
+ res = check_fd_events(ps, to, no_fds);
+ if (res != 0)
+ break;
+ if (to == ERTS_POLL_NO_TIMEOUT)
+ break;
+ if (erts_get_monotonic_time(NULL) >= timeout_time)
+ break;
+ }
woke_up(ps);