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ID Category Severity Reproducibility Date Submitted Last Update
0003956 [CentOS-5] CentOS-5-Plus feature N/A 2009-10-31 01:00 2009-11-05 15:39
Reporter toracat View Status public  
Assigned To
Priority normal Resolution open  
Status assigned   Product Version 5.4
Summary 0003956: RFE: relatime in plus kernel
Description Originally suggested/offered on the mailing list[1]:

"Is someone interested in the linux-2.6-smarter-relatime.patch for centosplus
kernel? This patch solves disk I/O performance dramatically on servers,
And recent distributions (fedora9 and later, etc.) and official kernel
applies it."

But the OP stopped responding. Then another person offered the patch in the CentOS forum[2].

"I've noticed a post on the mailing list regarding relatime option in the plus kernel. I never found a reply so I assume the original poster did not have a patch. I do have a patch and I'm wondering if it can be considered for the plus kernel. It is based on the Ingo Molnar's improve-relatime."

This is a good candidate for the centosplus kernel. Another option will be to provide the patched kernel as a .bz series.

[1] http://lists.centos.org/pipermail/centos/2009-July/079698.html [^]
[2] https://www.centos.org/modules/newbb/viewtopic.php?viewmode=flat&topic_id=22924&forum=37 [^]
Additional Information
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Attached Files

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-  Notes
(0010260)
toracat (developer)
2009-11-03 20:38

 I have built the cplus kernel with the proposed patch.

The config files needed couple of new lines. For example:

--- /ayplus/SOURCES/kernel-2.6.18-i686.config 2009-09-03 18:23:10.000000000 -0700
+++ /ayplus.relatime/SOURCES/kernel-2.6.18-i686.config 2009-10-29 18:11:08.000000000 -0700
@@ -3250,6 +3250,8 @@
 # CONFIG_CODA_FS is not set
 # CONFIG_AFS_FS is not set
 # CONFIG_9P_FS is not set
+CONFIG_DEFAULT_RELATIME=y
+CONFIG_DEFAULT_RELATIME_VAL=1

 #
 # Partition Types

However, problem is that this patch breaks the kABI. I was able to compile the kernel only by disabling kABI checking. Therefore, this may not be suitable for the cplus kernel which must remain kABI-compatible.
(0010297)
toracat (developer)
2009-11-05 15:39

 Most conversation is taking place in the forum thread quoted in the original report. Here's an excerpt.

toracat: I attempted to incorporate the patch into the centosplus kernel. However, the patch breaks the kABI and I had to disable kABI checking to get the kernel to compile. When you tried it with the regular kernel, did it work without any tweak like that?

gulikoza: yes the sysctl.c changes cause kABI breakage. If this is not desired perhaps you can leave that out (last 42 lines of the patch)
Also, depending on the config this will make relatime default. I don't mind since I run servers noatime and relatime is also default in new kernels but it is a difference from official kernel.

toracat: I would think that providing a separate set of kernels with the relatime patch is probably the way to go rather than integrating it into the cplus kernel. This way, people can test the patched kernel without having to use the cplus kernel. ... and yes, by omitting the sysctl.c patch, kernel compilation went through just fine.

- Issue History
Date Modified Username Field Change
2009-10-31 01:00 toracat New Issue
2009-10-31 01:00 toracat Assigned To => kbsingh@karan.org
2009-10-31 01:01 toracat Assigned To kbsingh@karan.org => toracat
2009-10-31 01:01 toracat Status new => assigned
2009-11-03 20:38 toracat Note Added: 0010260
2009-11-05 15:39 toracat Note Added: 0010297

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