Bug 127871 - voluntary preemption patch is not completely included
Summary: voluntary preemption patch is not completely included
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: rawhide
Hardware: i386
OS: Linux
medium
low
Target Milestone: ---
Assignee: Arjan van de Ven
QA Contact: Brian Brock
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2004-07-14 20:39 UTC by Hans Ecke
Modified: 2007-11-30 22:10 UTC (History)
1 user (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2004-07-15 17:48:26 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)

Description Hans Ecke 2004-07-14 20:39:57 UTC
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (compatible; Konqueror/3.2; Linux; en_US, en) (KHTML, like Gecko)

Description of problem:
In short: the version of voluntary preemption included in the latest  testing kernels misses features from the upstream version from Ingo Molnar. This is
   * voluntary and involuntary preemption can not be enabled at the same time
   * status of neither can be set in /proc/sys/kernel

++++++++++++++++++++++++++++++++

After reading the article about voluntary preemption at
   http://kerneltrap.org/node/view/3440
I wanted to try it out. Since Arjan's kernels from
   http://people.redhat.com/arjanv/2.6/
say that they include voluntary preemption, I downloaded kernel-sourcecode-2.6.7-1.486 and compiled a new kernel from that. (I need my own kernel for read access to NTFS, but that is the only difference to his default kernel)

Compiling the kernel showed the first difference to the article: PREEMPT and PREEMPT_VOLUNTARY can not be set at the same time.

Afer rebooting I wanted to see what /proc/sys/kernel/voluntary_preemption and /proc/sys/kernel/kernel_preemption say. But neither are available.

Looking through patches 1080, 1081, 1082 (from kernel-2.6.7-1.486.src.rpm) it becomes apparent that this version of voluntary preempt is quite a bit different from the one presented at
   http://people.redhat.com/mingo/voluntary-preempt

Is there a reason for that?



Version-Release number of selected component (if applicable):
kernel-(sourcecode-)2.6.7-1.486

How reproducible:
Always

Steps to Reproduce:
1.download kernel-2.6.7-1.486.src.rpm
2.rpm -i <file.src.rpm>
3.look at linux-2.6.7-voluntary-preemption.patch, linux-2.6.7-early-schedule.patch, linux-2.6.7-might_sleep.patch in /usr/src/redhat/SOURCES

    

Actual Results:  * when recompiling, PREEMPT and PREEMPT_VOLUNTARY can not be set at the same time
* knobs in /proc/sys/kernel are missing

Expected Results:  * when recompiling, PREEMPT and PREEMPT_VOLUNTARY should both be settable
* knobs in /proc/sys/kernel are available

Additional info:

This is not so much a bugreport as a request for comment: why did you cut those features out?

Comment 1 Arjan van de Ven 2004-07-15 07:57:39 UTC
the proc knobs in Ingo's patch were only temporary (as per his
announcement); the patch in the kernel rpm is closer to the final
form, eg it is always on and far less invasive to the kernel.

Comment 2 Hans Ecke 2004-07-15 17:48:26 UTC
Thanks for the information. 


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