From 2bace8b95108746f6123d312f47f5bda4eb17a26 Mon Sep 17 00:00:00 2001 From: Christian Thaeter Date: Sat, 25 Jul 2009 20:55:15 +0200 Subject: trivial: doc: hpfall: reduce risk that hpfall can do harm Improve the example code to be at least useable, as in not causing harm (as shown below). Code can still be improved further, but this adds some basic safeguards. 1. hpfall *MUST* mlockall(MCL_CURRENT|MCL_FUTURE); itself! Since the Program sits and waits most of the time it becomes very likely swapped out. If it gets woken up when the laptop drops from the table while it is swapped out it actually triggers harddrive activity! 2. Daemonize hpfall using 'daemon(0,0)' (quick and dirty). 3. Give hpfall realtime priority. Should give a chance that it has less latency when woken up. Signed-off-by: Christian Thaeter Signed-off-by: Frans Pop Acked-by: Pavel Machek Signed-off-by: Jiri Kosina --- Documentation/hwmon/hpfall.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'Documentation/hwmon/hpfall.c') diff --git a/Documentation/hwmon/hpfall.c b/Documentation/hwmon/hpfall.c index d2f6711b468..a3cfe1a5f96 100644 --- a/Documentation/hwmon/hpfall.c +++ b/Documentation/hwmon/hpfall.c @@ -16,6 +16,8 @@ #include #include #include +#include +#include void write_int(char *path, int i) { @@ -62,6 +64,7 @@ void ignore_me(void) int main(int argc, char *argv[]) { int fd, ret; + struct sched_param param; fd = open("/dev/freefall", O_RDONLY); if (fd < 0) { @@ -69,6 +72,11 @@ int main(int argc, char *argv[]) return EXIT_FAILURE; } + daemon(0, 0); + param.sched_priority = sched_get_priority_max(SCHED_FIFO); + sched_setscheduler(0, SCHED_FIFO, ¶m); + mlockall(MCL_CURRENT|MCL_FUTURE); + signal(SIGALRM, ignore_me); for (;;) { -- cgit v1.2.3