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author | Rickard Green <rickard@erlang.org> | 2011-12-16 13:02:09 +0100 |
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committer | Rickard Green <rickard@erlang.org> | 2012-04-16 16:32:28 +0200 |
commit | 414f4fb8dc9a188f8148a1f92e5f9125108e170d (patch) | |
tree | 319b52ff0171a0f3bec1deb63407caaefe095ab5 /erts/emulator/beam/erl_time_sup.c | |
parent | 3e454414a40bba082e5dc0be310f71843200dcf4 (diff) | |
download | otp-414f4fb8dc9a188f8148a1f92e5f9125108e170d.tar.gz otp-414f4fb8dc9a188f8148a1f92e5f9125108e170d.tar.bz2 otp-414f4fb8dc9a188f8148a1f92e5f9125108e170d.zip |
Optimize process table access
Diffstat (limited to 'erts/emulator/beam/erl_time_sup.c')
-rw-r--r-- | erts/emulator/beam/erl_time_sup.c | 85 |
1 files changed, 48 insertions, 37 deletions
diff --git a/erts/emulator/beam/erl_time_sup.c b/erts/emulator/beam/erl_time_sup.c index 1d0735aa99..c1b4408c06 100644 --- a/erts/emulator/beam/erl_time_sup.c +++ b/erts/emulator/beam/erl_time_sup.c @@ -91,6 +91,41 @@ static SysTimeval then; /* Used in get_now */ static SysTimeval last_emu_time; /* Used in erts_get_emu_time() */ SysTimeval erts_first_emu_time; /* Used in erts_get_emu_time() */ +union { + erts_smp_atomic_t time; + char align[ERTS_CACHE_LINE_SIZE]; +} approx erts_align_attribute(ERTS_CACHE_LINE_SIZE); + +static void +init_approx_time(void) +{ + erts_smp_atomic_init_nob(&approx.time, 0); +} + +static ERTS_INLINE erts_approx_time_t +get_approx_time(void) +{ + return (erts_approx_time_t) erts_smp_atomic_read_nob(&approx.time); +} + +static ERTS_INLINE void +update_approx_time(SysTimeval *tv) +{ + erts_approx_time_t new_secs = (erts_approx_time_t) tv->tv_sec; + erts_approx_time_t old_secs = get_approx_time(); + if (old_secs != new_secs) + erts_smp_atomic_set_nob(&approx.time, new_secs); +} + +/* + * erts_get_approx_time() returns an *approximate* time + * in seconds. NOTE that this time may jump backwards!!! + */ +erts_approx_time_t +erts_get_approx_time(void) +{ + return get_approx_time(); +} #ifdef HAVE_GETHRTIME @@ -398,6 +433,8 @@ erts_init_time_sup(void) { erts_smp_mtx_init(&erts_timeofday_mtx, "timeofday"); + init_approx_time(); + last_emu_time.tv_sec = 0; last_emu_time.tv_usec = 0; @@ -417,7 +454,7 @@ erts_init_time_sup(void) gtv = inittv; then.tv_sec = then.tv_usec = 0; - erts_get_emu_time(&erts_first_emu_time); + erts_deliver_time(); return CLOCK_RESOLUTION; } @@ -873,6 +910,8 @@ get_now(Uint* megasec, Uint* sec, Uint* microsec) *megasec = (Uint) (now.tv_sec / 1000000); *sec = (Uint) (now.tv_sec % 1000000); *microsec = (Uint) (now.tv_usec); + + update_approx_time(&now); } void @@ -885,6 +924,8 @@ get_sys_now(Uint* megasec, Uint* sec, Uint* microsec) *megasec = (Uint) (now.tv_sec / 1000000); *sec = (Uint) (now.tv_sec % 1000000); *microsec = (Uint) (now.tv_usec); + + update_approx_time(&now); } @@ -901,6 +942,8 @@ void erts_deliver_time(void) { do_erts_deliver_time(&now); erts_smp_mtx_unlock(&erts_timeofday_mtx); + + update_approx_time(&now); } /* get *real* time (not ticks) remaining until next timeout - if there @@ -949,6 +992,7 @@ void erts_get_timeval(SysTimeval *tv) erts_smp_mtx_lock(&erts_timeofday_mtx); get_tolerant_timeofday(tv); erts_smp_mtx_unlock(&erts_timeofday_mtx); + update_approx_time(tv); } erts_time_t @@ -961,7 +1005,9 @@ erts_get_time(void) get_tolerant_timeofday(&sys_tv); erts_smp_mtx_unlock(&erts_timeofday_mtx); - + + update_approx_time(&sys_tv); + return sys_tv.tv_sec; } @@ -977,38 +1023,3 @@ void erts_get_now_cpu(Uint* megasec, Uint* sec, Uint* microsec) { *sec = (Uint)(tp.tv_sec % 1000000); } #endif - - -/* - * erts_get_emu_time() is similar to get_now(). You will - * always get different times from erts_get_emu_time(), but they - * may equal a time from get_now(). - * - * erts_get_emu_time() is only used internally in the emulator in - * order to order emulator internal events. - */ - -void -erts_get_emu_time(SysTimeval *this_emu_time_p) -{ - erts_smp_mtx_lock(&erts_timeofday_mtx); - - get_tolerant_timeofday(this_emu_time_p); - - /* Make sure time is later than last */ - if (last_emu_time.tv_sec > this_emu_time_p->tv_sec || - (last_emu_time.tv_sec == this_emu_time_p->tv_sec - && last_emu_time.tv_usec >= this_emu_time_p->tv_usec)) { - *this_emu_time_p = last_emu_time; - this_emu_time_p->tv_usec++; - } - /* Check for carry from above + general reasonability */ - if (this_emu_time_p->tv_usec >= 1000000) { - this_emu_time_p->tv_usec = 0; - this_emu_time_p->tv_sec++; - } - - last_emu_time = *this_emu_time_p; - - erts_smp_mtx_unlock(&erts_timeofday_mtx); -} |