Bug 68908

Summary: real time scheduling is broken
Product: [Retired] Red Hat Linux Reporter: Till Straumann <strauman>
Component: kernelAssignee: Arjan van de Ven <arjanv>
Status: CLOSED ERRATA QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 7.3   
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
URL: http://www-hft.ee.tu-berlin.de/~strauman/tp4utils/index.html
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2002-07-15 21:03:24 UTC Type: ---
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description Flags
patch fixing broken rh7.2/linux-2.4.18-4 sched_setscheduler() etc. syscall none

Description Till Straumann 2002-07-15 21:00:26 UTC 
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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,&params) will always
show a PRI >= 0.


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


How reproducible:
Always

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

http://www-hft.ee.tu-berlin.de/~strauman/tp4utils/index.html
Comment 1 Till Straumann 2002-07-15 21:03:20 UTC 
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 18:28:15 UTC 
this has been fixed in 2.4.18-5 already, which has been released as erratum a
while ago