Red Hat Bugzilla – Bug 68908
real time scheduling is broken
Last modified: 2007-04-18 12:44:12 EDT
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Description of problem:
The linux-2.4.17-selected-ac-bits.patch breaks real-time scheduling.
A process trying to get real-time priority (sched_setscheduler())
will never really get the requested priority (although sched_getparam())
reports the correct rt_priority).
'ps l' should report a negative PRI for real-time processes but a process
calling sched_setscheduler(0,SCHED_FIFO,¶ms) will always
show a PRI >= 0.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1.Let a program call sched_setscheduler(0,SCHED_OTHER,&appropriate_param)
2. run as root
3. test behavior. Run 'ps l'. The process will not be RT scheduled
Actual Results: Process didn't effectively get RT priority
Programs relying on real-time scheduling (e.g. CD burner) may lose data.
Proposed Fix: see patch available at
Created attachment 65484 [details]
patch fixing broken rh7.2/linux-2.4.18-4 sched_setscheduler() etc. syscall
this has been fixed in 2.4.18-5 already, which has been released as erratum a