On Fri, 11 Sep 2020 17:45:38 +0200 Christian Eggers <[email protected]> wrote:
> musl "implements" several sched_xxx() functions by returning ENOSYS. As > an alternative, either pthread_(g|s)etschedparam() or direct syscalls > can be used. I don't like using the syscalls directly in the way you propose below. OTOH pulling in pthread for the pedantically correct pthread_ functions is crude. But then, nowadays, the Threads option is part of Base, so what exactly is the objection from the musl folks so they stub out sched_getscheduler? thanks, > > References: > https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/schedutils/chrt.c?id=fcc3078754291d2f5121797eb91b364f8e24b2f1 > References: > http://git.musl-libc.org/cgit/musl/commit/src/sched/sched_setscheduler.c?id=1e21e78bf7a5c24c217446d8760be7b7188711c2 > Signed-off-by: Christian Eggers <[email protected]> > --- > util-linux/chrt.c | 31 +++++++++++++++++++++++++++++-- > 1 file changed, 29 insertions(+), 2 deletions(-) > > diff --git a/util-linux/chrt.c b/util-linux/chrt.c > index 4dd78dabf..e465d7cec 100644 > --- a/util-linux/chrt.c > +++ b/util-linux/chrt.c > @@ -34,6 +34,9 @@ > //usage: "You need CAP_SYS_NICE privileges to set scheduling > attributes of a process" > > #include <sched.h> > +#if defined (__linux__) > +# include <sys/syscall.h> > +#endif > #include "libbb.h" > #ifndef SCHED_IDLE > # define SCHED_IDLE 5 > @@ -85,6 +88,7 @@ int chrt_main(int argc UNUSED_PARAM, char **argv) > char *priority = priority; /* for compiler */ > const char *current_new; > int policy = SCHED_RR; > + int ret; > > opt = getopt32(argv, "^" > "+" "mprfobi" > @@ -132,7 +136,15 @@ int chrt_main(int argc UNUSED_PARAM, char **argv) > if (opt & OPT_p) { > int pol; > print_rt_info: > +#if defined (__linux__) && defined(SYS_sched_getscheduler) > + /* musl libc returns ENOSYS for its sched_getscheduler library > + * function, because the sched_getscheduler Linux kernel system > call > + * does not conform to Posix; so we use the system call directly > + */ > + pol = syscall(SYS_sched_getscheduler, pid); > +#else > pol = sched_getscheduler(pid); > +#endif > if (pol < 0) > bb_perror_msg_and_die("can't %cet pid %u's policy", > 'g', (int)pid); > #ifdef SCHED_RESET_ON_FORK > @@ -149,7 +161,12 @@ int chrt_main(int argc UNUSED_PARAM, char **argv) > printf("pid %u's %s scheduling policy: SCHED_%s\n", > pid, current_new, policy_name(pol) > ); > - if (sched_getparam(pid, &sp)) > +#if defined (__linux__) && defined(SYS_sched_getparam) > + ret = syscall(SYS_sched_getparam, pid, &sp); > +#else > + ret = sched_getparam(pid, &sp); > +#endif > + if (ret) > bb_perror_msg_and_die("can't get pid %u's attributes", > (int)pid); > printf("pid %u's %s scheduling priority: %d\n", > (int)pid, current_new, sp.sched_priority > @@ -168,7 +185,17 @@ int chrt_main(int argc UNUSED_PARAM, char **argv) > sched_get_priority_min(policy), sched_get_priority_max(policy) > ); > > - if (sched_setscheduler(pid, policy, &sp) < 0) > +#if defined (__linux__) && defined(SYS_sched_setscheduler) > + /* musl libc returns ENOSYS for its sched_setscheduler library > + * function, because the sched_setscheduler Linux kernel system call > + * does not conform to Posix; so we use the system call directly > + */ > + ret = syscall(SYS_sched_setscheduler, pid, policy, &sp); > +#else > + ret = sched_setscheduler(pid, policy, &sp); > +#endif > + > + if (ret < 0) > bb_perror_msg_and_die("can't %cet pid %u's policy", 's', > (int)pid); > > if (!argv[0]) /* "-p PRIO PID [...]" */ _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
