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author | Denys Vlasenko | 2020-12-11 16:48:47 +0100 |
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committer | Denys Vlasenko | 2020-12-11 16:48:47 +0100 |
commit | 030fe31760169783537162b83af89e551bf120f6 (patch) | |
tree | 92b219784b478405626b9259b82900ab3ca72a8e /libbb | |
parent | 56ee5765074b2f2389066f3234a4da21501d3eaa (diff) | |
download | busybox-030fe31760169783537162b83af89e551bf120f6.zip busybox-030fe31760169783537162b83af89e551bf120f6.tar.gz |
libbb: make msleep() result in only one syscall instead of looping
function old new delta
msleep 45 52 +7
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'libbb')
-rw-r--r-- | libbb/bb_do_delay.c | 18 | ||||
-rw-r--r-- | libbb/platform.c | 1 |
2 files changed, 18 insertions, 1 deletions
diff --git a/libbb/bb_do_delay.c b/libbb/bb_do_delay.c index 3dbf032..9a84fa2 100644 --- a/libbb/bb_do_delay.c +++ b/libbb/bb_do_delay.c @@ -36,6 +36,7 @@ void FAST_FUNC sleep1(void) void FAST_FUNC msleep(unsigned ms) { +#if 0 /* 1. usleep(n) is not guaranteed by standards to accept n >= 1000000 * 2. multiplication in usleep(ms * 1000) can overflow if ms > 4294967 * (sleep of ~71.5 minutes) @@ -46,4 +47,21 @@ void FAST_FUNC msleep(unsigned ms) ms -= 500; } usleep(ms * 1000); +#else +//usleep is often implemented as a call to nanosleep. +//Simply do the same to implement msleep. +//it's marginally larger, but wakes your CPU less often: +//function old new delta +//msleep 45 52 +7 + struct timespec ts; + ts.tv_sec = ms / 1000; + ts.tv_nsec = (ms % 1000) * 1000000; + /* + * If a signal has non-default handler, nanosleep returns early. + * Our version of msleep doesn't return early + * if interrupted by such signals: + */ + while (nanosleep(&ts, &ts) != 0) + continue; +#endif } diff --git a/libbb/platform.c b/libbb/platform.c index d2b263a..329b023 100644 --- a/libbb/platform.c +++ b/libbb/platform.c @@ -27,7 +27,6 @@ int FAST_FUNC usleep(unsigned usec) * If a signal has non-default handler, nanosleep returns early. * Our version of usleep doesn't return early * if interrupted by such signals: - * */ while (nanosleep(&ts, &ts) != 0) continue; |