Bug 68908 - real time scheduling is broken
real time scheduling is broken
Product: Red Hat Linux
Classification: Retired
Component: kernel (Show other bugs)
All Linux
medium Severity medium
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Assigned To: Arjan van de Ven
Brian Brock
Depends On:
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Reported: 2002-07-15 17:00 EDT by Till Straumann
Modified: 2007-04-18 12:44 EDT (History)
0 users

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Last Closed: 2002-07-15 17:03:24 EDT
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RHEL 7.3 requirements from Atomic Host:
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Attachments (Terms of Use)
patch fixing broken rh7.2/linux-2.4.18-4 sched_setscheduler() etc. syscall (1.04 KB, patch)
2002-07-15 17:03 EDT, Till Straumann
no flags Details | Diff

  None (edit)
Description Till Straumann 2002-07-15 17:00:26 EDT
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.9) Gecko/20020513

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,&params) will always
show a PRI >= 0.

Version-Release number of selected component (if applicable):

How reproducible:

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

Additional info:

Programs relying on real-time scheduling (e.g. CD burner) may lose data.

Proposed Fix: see patch available at

Comment 1 Till Straumann 2002-07-15 17:03:20 EDT
Created attachment 65484 [details]
patch fixing broken rh7.2/linux-2.4.18-4 sched_setscheduler() etc. syscall
Comment 2 Arjan van de Ven 2002-07-17 14:28:15 EDT
this has been fixed in 2.4.18-5 already, which has been released as erratum a
while ago

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