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Diffstat (limited to 'man7/sched.7')
| -rw-r--r-- | man7/sched.7 | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/man7/sched.7 b/man7/sched.7 index 8eac1c2dbc..1077679144 100644 --- a/man7/sched.7 +++ b/man7/sched.7 @@ -379,6 +379,29 @@ and increased for each time quantum the thread is ready to run, but denied to run by the scheduler. This ensures fair progress among all \fBSCHED_OTHER\fP threads. .\" +.SS The nice value +The range of the nice value +varies across UNIX systems. +On modern Linux, the range is \-20 (high priority) to +19 (low priority). +On some other systems, the range is \-20..20. +Very early Linux kernels (Before Linux 2.0) had the range \-infinity..15. +.\" Linux before 1.3.36 had \-infinity..15. +.\" Since kernel 1.3.43, Linux has the range \-20..19. + +The degree to which the nice value affects the relative scheduling of +.BR SCHED_OTHER +processes likewise varies across UNIX systems and +across Linux kernel versions. + +With the advent of the CFS scheduler in kernel 2.6.23, +Linux adopted an algorithm that causes +relative differences in nice values to have a much stronger effect. +This causes very low nice values (+19) to truly provide little CPU +to a process whenever there is any other +higher priority load on the system, +and makes high nice values (\-20) deliver most of the CPU to applications +that require it (e.g., some audio applications). +.\" .SS SCHED_BATCH: Scheduling batch processes (Since Linux 2.6.16.) \fBSCHED_BATCH\fP can be used only at static priority 0. |