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What are the advantages & benefits of using ELRepo LTS Kernel?

Discussion in 'Dedicated server hosting' started by rdan, May 17, 2022.

  1. rdan

    rdan Premium Member Premium Member

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    Be able to use?
    1. Nginx KTLS
    2. Nginx io_uring
    3. TCP BBR
    4. ???


     
    Last edited: May 17, 2022
  2. eva2000

    eva2000 Administrator Staff Member

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    I think all the above for both LTS and mainline Linux Kernels. Those LTS Linux Kernel is more for stability versus the mainline Linux Kernel. LTS is at 5.17 right now while mainline is at 5.18 https://kernel.org/. IIRC 5.18 Linux Kernel has a few more fixes/improvements for newer AMD EPYC Milan cpus.
     
  3. rdan

    rdan Premium Member Premium Member

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  4. buik

    buik “The best traveler is one without a camera.”

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    I want to bring The Unbreakable Enterprise Kernel (UEK) from Oracle to your attention. UEK is well-tested and made specifically for EL-based systems.

    The latest UEK kernel is formally based upon upstream Kernel 5.4.
    However, a 5.15 flavor will also be available as UEK7, soon.
    So all the reqested features are available.

    EL7 does not support AMD Milan based servers.
    So theoretically you have little use for that.

    However you could try booting brand new hardware with the Oracle Linux 7 + UEK kernel boot CD. Although I don't know if Centminmod runs on EL7 clones like Oracle Linux 7.
    I've simply never tested it.
     
  5. eva2000

    eva2000 Administrator Staff Member

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    Centmin Mod doesn't support Oracle Linux 7.

    whoops, was thinking of kernel.org heh

    I think it depends on hardware used, seems some web hosts do offer it - but not many. Both OVH and Hivelocity offer AMD EPYC Milan 3rd gen cpus with listed CentOS 7 support. OVH doesn't support AMD Ryzen 5xxx series though.

    For OVH you have to check it on compare server listings page outline. Of course, listing it as supported and actually supported I wouldn't know as I don't have the budget or requirements to use AMD EPYC Milan myself.

    OVH's Intel E-23XX Rocket Lake and AMD EPYC Milan 7xx3 both listed with CentOS 7 support

    ovh-centos7-milan-os-support-01.png
    ovh-centos7-milan-os-support-02.png
     
  6. rdan

    rdan Premium Member Premium Member

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    Do you use it on CMM based server?

    So install commands would be?
    Code:
    nano /etc/yum.repos.d/ol7_UEKR6.repo
    
    Code:
    [ol7_UEKR6]
    name=Latest Unbreakable Enterprise Kernel Release 6 for Oracle Linux $releasever ($basearch)
    baseurl=https://yum.oracle.com/repo/OracleLinux/OL7/UEKR6/$basearch/
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-oracle
    gpgcheck=1
    enabled=1
    
    Code:
    rpm --import http://public-yum.oracle.com/RPM-GPG-KEY-oracle-ol7
    yum -y install kernel-uek
    grub2-mkconfig -o /boot/grub2/grub.cfg
    grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg
    
    awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg
    sudo grub2-set-default 0
    reboot
    
    Almost no guide found on Google search.
     
  7. buik

    buik “The best traveler is one without a camera.”

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    Seems like a general picture and a general list since Ubuntu 18* LTS is not supported on Xeon-E 2* and so on not listed. Which should work since it is officially supported by Ubuntu.

    EL7 could work on new hardware with a Hybrid Kernel. Just what CloudLinux did.
    Cloudlinux 7 with 'Hybrid Kernel' is supported on EPYC 3 and AMD Ryzen 5*.

    Apparently OVH and Hivelocity seems using a Hybrid Kernel for their images on new hardware. Although I am not a customer. As, once again, upstream EL7 does not have support for new hardware.
     
    Last edited: May 17, 2022
  8. buik

    buik “The best traveler is one without a camera.”

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    Nope. I am not using a different kernel on production. Only test servers.
    The above tweaks only work effective when dealing with large systems with many visitors/data etc. That's what so-and-so was developed for a Google, Amazon or Facebook where every 0.0.1% counts. But with low-data "normal websites" like ours, that almost doesn't come into play. My opinion and tests also affirm this.

    When a single node does not consume TB's of data per day it is in my opinion (cost/benefit) not effective enough to spend time and time to tweak servers over and over again. And you can better put that time in creating new content. To push websites to the top.

    Seems Broadcom is using the UEK kernel on CentOS 7 in one or another way.

    Add the Unbreakable Enterprise Kernel Release 4 for Oracle Linux 7 repository to CentOS 7.x

    Other how-to's:
    https://geraldonit.com/2018/07/09/upgrading-uek-kernel-on-oracle-linux-7/

    https://webhostinggeeks.com/howto/switching-default-uek-kernel-to-redhat-kernel-on-oracle-linux-7/

    Install Oracle Linux UEKR3 on CentOS7 | linuxsysconfig

    Even in Russian, for our Russian guests:
    Установка ядра Oracle UEK R6 на CentOS 7 | Блог Михаила Григорьева
     
    Last edited: May 18, 2022
  9. eva2000

    eva2000 Administrator Staff Member

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  10. rdan

    rdan Premium Member Premium Member

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    Based on testing and loader.io benchmark, KTLS doesn't improve much.
    Even downgraded performance for PHP request.
     
  11. eva2000

    eva2000 Administrator Staff Member

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  12. rdan

    rdan Premium Member Premium Member

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    I din't post my PHP request result because it's not worth it with KLTS enabled :D
     
  13. eva2000

    eva2000 Administrator Staff Member

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    Hence, you haven't heard much from me regarding Nginx KTLS either :)
     
  14. rdan

    rdan Premium Member Premium Member

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    So from the list above, only advantage of using 5.x Kernel is TCP BBR.
     
  15. eva2000

    eva2000 Administrator Staff Member

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    Yeah I think for nginx kTLS probably need accompanying supported network adaptor cards too.
     
  16. buik

    buik “The best traveler is one without a camera.”

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    Besides the advantages vs disadvantages. Where you been able to run the Oracle UEK kernel?
     
  17. rdan

    rdan Premium Member Premium Member

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    I haven't tried yet.