CentOS 5 - realtime patch

Question

Where can I download precompiled CentOS 5 kernel including realtime patch? Or I need to compile it myself (if yes, how to do that)?

Solution

While I own a few RHEL MRG licenses, I've started using the FREE realtime recompile of http://www.redhat.com/mrg/">Red Hat MRG from Scientific Linux to convert my CentOS 5 servers to realtime. You can view the Scientific Linux MRG distribution at: http://glitesoft.cern.ch/cern/mrg/slc5X/x86_64/RPMS/

In order to install, I create a small repo file named slc5x-mrg-realtime.repo and drop it in /etc/yum.repos.d. The file contains:

[slc-mrg-realtime]
name = SLC5X - MRG Realtime
baseurl = http://linuxsoft.cern.ch/cern/mrg/slc5X/$basearch/RPMS
enabled = 1
protect = 0
gpgkey = http://glitesoft.cern.ch/cern/slc44/x86_64/RPM-GPG-KEYs/RPM-GPG-KEY-cern
gpgcheck = 1

From there, I can simply run yum grouplist and see the MRG component groups:

   MRG Realtime
   MRG Grid
   MRG Management
   MRG Messaging

A yum groupinstall "MRG Realtime" && yum install kernel-rt-devel gives me everything I need for realtime operation. You can also just pick and choose the files you want from the distro's rpm listing page at: http://glitesoft.cern.ch/cern/mrg/slc5X/x86_64/RPMS/

---

Another option is to perform a recompile of Red Hat's SRPMS available at: http://ftp.redhat.com/pub/redhat/linux/enterprise/5Server/en/RHEMRG/SRPMS/

It's the standard rpmbuild --rebuild package.srpm process. This takes more time, but I've done this successfully as well.

Comments

[Red Tux]

Have you gone searching through the CentOS forums? A quick Google search yeilded a few hits. Also why do you need the real time patch? Perhaps changing your process scheduler to something like the deadline scheduler might be just as suitable.

[Dima]

@Red Tux: I tried to search and I got only MRG project, but I prefer to use something free. About deadline scheduler: I've never heard of it. I don't know what better for me, I'm implementing server that receiving big number of UDP packets per seconds and I got missing packets even I set receiver thread priority to 99 with SCHED_FIFO. I think, to use real-time path will be enough?

[ewwhite]

This is right in the sweet-spot for a realtime kernel. You will notice a difference. The benefit of the solution I posted below is that you will be able to test the realtime kernel without making any major changes to your operating system installation. RHEL MRG is an add-on to the base Enterprise Linux product.

[Dima]

I prefer to use free SW (not commercial MRG) How can I know, which RT path I need for CentOS 5.5 kernel? My Kernel version is: 2.6.18-194.26.1.el5, as I see, the latest version of the RT patch for 2.6.18 is patch-2.6.18-rt7. Is it OK to use use it?

[ewwhite]

Please reread my comment. I've provided you two free solutions. Scientific Linux IS free! It has a clone of RHEL MRG in the sane manner that CentOS is a clone of RHEL. MRG is a new kernel and a set of utilities, not a patch.