Hello Yang Xu, Cyrill, On 7/24/19 8:52 AM, Yang Xu wrote: > In kernel/sys.c, arg2 is an unsigned long value and it will never > less than 0. Also, since kernel commit id da8b44d5a9f8, timer_slack_ns > and default timer_slack_ns have been converted into u64, the return > value of PR_GET_TIMERSLACK has been limited under ULONG_MAX. > > The timer slack value also can be inherited by a child created via > fork(2). Thank you for the patch! I've applied it. Cyrill, thanks for the review. Cheers, Michael > Signed-off-by: Yang Xu <xuyang2018.jy@xxxxxxxxxxxxxx> > --- > man2/prctl.2 | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/man2/prctl.2 b/man2/prctl.2 > index 52fd0f3f3..348a39f6a 100644 > --- a/man2/prctl.2 > +++ b/man2/prctl.2 > @@ -1239,14 +1239,15 @@ this operation expects a user-space buffer of 8 (not 4) bytes on these ABIs. > Each thread has two associated timer slack values: > a "default" value, and a "current" value. > This operation sets the "current" timer slack value for the calling thread. > +.I arg2 > +is an unsigned long value, then maximum "current" value is ULONG_MAX and > +the minimum "current" value is 1. > If the nanosecond value supplied in > .IR arg2 > is greater than zero, then the "current" value is set to this value. > If > .I arg2 > -is less than or equal to zero, > -.\" It seems that it's not possible to set the timer slack to zero; > -.\" The minimum value is 1? Seems a little strange. > +is equal to zero, > the "current" timer slack is reset to the > thread's "default" timer slack value. > .IP > @@ -1291,7 +1292,9 @@ The timer slack values of > .IR init > (PID 1), the ancestor of all processes, > are 50,000 nanoseconds (50 microseconds). > -The timer slack values are preserved across > +The timer slack value is inherited by a child created via > +.BR fork(2), > +and is preserved across > .BR execve (2). > .IP > Since Linux 4.6, the "current" timer slack value of any process > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
