diff options
| -rw-r--r-- | SConstruct | 1 | ||||
| -rw-r--r-- | build.txt | 14 | ||||
| -rw-r--r-- | gpsd.c | 82 |
3 files changed, 0 insertions, 97 deletions
@@ -155,7 +155,6 @@ boolopts = ( ("nofloats", False, "float ops are expensive, suppress error estimates"), ("squelch", False, "squelch gpsd_report/gpsd_hexdump to save cpu"), ("ncurses", True, "build with ncurses"), - ("buzzkill", True, "adaptive-delay logic to cope with select buzzing"), # Build control ("shared", True, "build shared libraries, not static"), ("implicit_link", imloads,"implicit linkage is supported in shared libs"), @@ -352,20 +352,6 @@ scons minimal=yes socket_export=yes nmea0183=yes will do that. -buzzkill=yes: this option is intended to thwart problems due to gpsd's -main select(2) loop buzzing (spinning too fast). On battery-powered -SBCs and mobile devices this can cause serious and unnecessary power -drain; this has been observed on the Raspberry Pi and sporadically on -particular Android phone hardware. There are at least two reasons it -can happen; one is defective select(2) device-driver hooks that return -a data-ready when they shouldn't, the other is tty layers that return -data in single characters or small packets even when it's arriving in -packet-sized chunks. GPSD with buzzkill=yes watches the incoming data -rate from all devices and adaptively inserts delays in the main loop -if it thinks it sees buzzing. This logic is routed around if all -devices have types that never require delays, notably pseudo-ttys and -UDP packet streams. - == Port and toolchain testing == 'scons check' will run a comprehensive regression-test suite. You @@ -1759,73 +1759,6 @@ static void gpsd_terminate(struct gps_context_t *context CONDITIONALLY_UNUSED) #endif /* PPS_ENABLE */ } -#ifdef BUZZKILL_ENABLE -#define SLEEP_THRESHOLD 4.0 /* delay if avg is less than this */ - -static void adaptive_delay(void) -/* sleep a calculated time only if we have a buggy select() */ -{ - struct gps_device_t *devp; - unsigned int mightbuzz; - bool buzzlock; - useconds_t delay; - - if (context.inbytesavg <= SLEEP_THRESHOLD && !context.selectbug) { - gpsd_report(&context.errout, LOG_WARN, - "select() bug found, adaptive delays will be inserted\n"); - context.selectbug = true; - } - - /* - * Don't do anything if we don't have enough data + - * or if the select bug is not present - */ - if (!context.selectbug) - return; - if (context.inbyteswpos != (unsigned char)WINDOW_AVG_SIZE) - return; - - /* count the number of devices which might buzz */ - mightbuzz = 0; - buzzlock = false; - for (devp = devices; devp < devices + MAX_DEVICES; devp++) - if (allocated_device(devp) && devp->gpsdata.gps_fd > 0) { - if (devp->sourcetype==source_rs232 || devp->sourcetype==source_usb) - mightbuzz++; - /* - * Some fast devices will lose packets if delays are enabled. - * Allow them to lock out delays. - */ - if (devp->sourcetype == source_can) - buzzlock = true; - } - - /* - * Because ptys are not counted, we avoid delay insertion if we're - * running inside a test harness. Without this check the - * regression tests fail. - */ - if (mightbuzz > 0 && !buzzlock) { - delay = (useconds_t)(5000UL/mightbuzz); -#ifdef __UNUSED__ - /* - * We started with this more complex formula. It worked well - * on the Raspberry Pi but produced client hangs elsewhere due - * to excessively long delays. - */ -#define SLEEP_FACTOR 4700000U /* controls the formula to compute delay */ - delay = (useconds_t)(SLEEP_FACTOR/context.inbytesavg); - if (delay > (useconds_t) (500000UL/mightbuzz) ) - delay = (useconds_t) (500000UL/mightbuzz); -#endif /* __UNUSED__ */ - gpsd_report(&context.errout, LOG_SPIN, - "adaptive delay, sleeping for %u usec\n",delay); - (void) usleep(delay); - } - return; -} -#endif /* BUZZKILL_ENABLE */ - /*@ -mustfreefresh @*/ int main(int argc, char *argv[]) { @@ -2205,21 +2138,6 @@ int main(int argc, char *argv[]) while (0 == signalled) { fd_set efds; -#ifdef BUZZKILL_ENABLE - /* - * Adaptive delay to prevent buzzing if the tty layer returns - * data one character at a time and too fast. Buzzing pushes - * CPU usage up and eats power. - * - * This has been directly observed as a problem on the - * Raspberry Pi. A buzzing problem with outright defective - * select(2) implementations is probably behind occasional - * reports of GPSD-related excessive power drain on Android - * phones. - */ - (void) adaptive_delay(); -#endif /* BUZZKILL_ENABLE */ - switch(gpsd_await_data(&rfds, &efds, maxfd, &all_fds, &context.errout)) { case AWAIT_GOT_INPUT: |