CloudLinux - CloudLinux Blog - Beta: CloudLinux 6 Hybrid kernel 3.10 released

Beta: CloudLinux 6 Hybrid kernel 3.10 released

Beta: CloudLinux 6 Hybrid kernel 3.10 released

New updated CloudLinux 6 Hybrid kernel is available from our updates-testing repository.

New 3.10 kernel features a set of performance and scalability improvements related to IO, networking and memory management.

It also features improved CPU scheduler for better overall system throughput and latency.

One of the key reasons for us to deliver 3.10 kernel for CL6 servers is due to some of the new features that we are working on.

One of the features is mod_lsapi PHP process checkpointing that would provide significant speed improvement for serving the first page. For web applications like WordPress, the first page often takes 10x as much time to serve as subsequent pages. mod_lsapi checkpointing solves this problem, bringing the first page serve times in line with consequent pages. Yet, to deliver this feature 3.10 kernel is necessary.

Similarly, we are actively working on two level LVE limits, to allow hosters to limit resources for resellers, while resellers will be able to limit resources for individual end users. Once again, the feature will only be available with 3.10 kernel.

You can find the information on the main features of 3.10 kernel branch on the following links:

In short:

  • IO scalability improvements, async IO support added;

  • enhanced networking;

  • future: support for CRIU (mod_lsapi checkpointing);

  • future: two level limits.

How to migrate from normal to hybrid channel:

Note. The system must be registered in CLN.

1. Update rhn-clients-tools from beta.

2. Run normal-to-hybrid script.

3. Reboot after script execution is completed.

yum update rhn-clients-tools --enablerepo=cloudlinux-updates-testing

How to migrate from hybrid to normal channel:

Note. The system must be registered in CLN.

1. Run hybrid-to-normal script.

2. Reboot after script execution is completed.


Known limitations and issues:

1. We do not remove Hybrid kernel after migration from Hybrid to normal channel, but we remove linux-firmware package which is needed to boot Hybrid kernel. This is because CL6 does not allow to remove the package of currently running kernel. Proper removal procedure will be implemented, but for now we should warn users not to boot Hybrid kernel if they have migrated to normal channel.

2. Kernel module signature isn't checking for now, as 3.10 kernel is using x509 certificates to generate keys and CL6 cannot detect signatures created in such way. Solution will be implemented.

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