Hello Robin,
On 06/30/2016 12:35 AM, Robin Kuzmin wrote:
http://man7.org/linux/man-pages/man2/getpriority.2.html 2015-07-23
1.
What I see: "lower priorities cause more favorable scheduling".
What I expect: "lower values (higher priority) cause more favorable
scheduling".
2.
What I see: "Only the superuser may lower priorities".
What I expect: "Only the superuser may lower values (boost/increase the
priorities)".
3.
What I see: "The caller attempted to lower a process priority".
What I expect: "The caller attempted to lower a priority value (to increase
a priority)".
4.
Add to section "SEE ALSO" the reference to "nice(2)" -
http://man7.org/linux/man-pages/man2/nice.2.html
Why I think so: The man page GETPRIORITY(2) should be in synch with nice(2)
http://man7.org/linux/man-pages/man2/nice.2.html
Both getpriority(2) and nice(2) are referred by sched(7) section
"SCHED_OTHER: Default Linux time-sharing scheduling" -
http://man7.org/linux/man-pages/man7/sched.7.html.
Thanks for the note. The text could indeed be better. I've made
various changes, including your suggestions. See the diff below.
Thanks for the report.
Cheers,
Michael
--- a/man2/getpriority.2
+++ b/man2/getpriority.2
@@ -64,6 +64,9 @@ is obtained with the
call and set with the
.BR setpriority ()
call.
+The process attribute dealt with by these system calls is
+the same attribute (also known as the "nice" value) that is dealt with by
+.BR nice (2).
The value
.I which
@@ -87,11 +90,13 @@ A zero value for
.I who
denotes (respectively) the calling process, the process group of the
calling process, or the real user ID of the calling process.
+
The
.I prio
argument is a value in the range \-20 to 19 (but see NOTES below).
+with \-20 being the highest priority and 19 being the lowest priority.
The default priority is 0;
-lower priorities cause more favorable scheduling.
+lower values give a process a higher scheduling priority.
The
.BR getpriority ()
@@ -101,7 +106,15 @@ The
.BR setpriority ()
call sets the priorities of all of the specified processes
to the specified value.
-Only the superuser may lower priorities.
+
+Traditionally, only a privileged process could lower the nice value
+(i.e., set a higher priority).
+However, since Linux 2.6.12, an unprivileged process can decrease
+the nice value of a target process that has a suitable
+.BR RLIMIT_NICE
+soft limit; see
+.BR getrlimit (2)
+for details.
.SH RETURN VALUE
Since
.BR getpriority ()
@@ -137,16 +150,11 @@ In addition to the errors indicated above,
may fail if:
.TP
.B EACCES
-The caller attempted to lower a process priority, but did not
+The caller attempted to set a lower nice value
+(i.e., a higher process priority), but did not
have the required privilege (on Linux: did not have the
.B CAP_SYS_NICE
capability).
-Since Linux 2.6.12, this error occurs only if the caller attempts
-to set a process priority outside the range of the
-.B RLIMIT_NICE
-soft resource limit of the target process; see
-.BR getrlimit (2)
-for details.
.TP
.B EPERM
A process was located, but its effective user ID did not match
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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