About Linux FAQ

Browse More FAQs:

Linux Disable Hyper Threading for Pentium 4 server GRUB boot loader

Posted by Vivek Gite [Last updated: November 6, 2006]

Q. I am using GRUB boot loader. How do I disable Hyper Threading for Pentium 4 server? I am using CentOS.

A. To improve performance in the past, threading was enabled in the software by splitting instructions into multiple streams so that multiple processors could act upon them. Hyper-Threading Technology (HT Technology) provides thread-level parallelism on each processor, resulting in more efficient use of processor resources, higher processing throughput, and improved performance on today's multithreaded software.

If you disable HT you may notice performance problem. To disable edit grub.conf file:
# vi /etc/grub.conf
OR
# vi /boot/grub/menu.lst

Locate the kernel line that you want to modify and append noht at the end:
kernel /boot/vmlinuz-2.6.8-2-686 root=/dev/hdb1 ro single noht

Save and close the file.

You can also disable HT during booting CentOS Linux. You need to pass an option to kernel.

  1. At GRUB menu
  2. Select the kernel to boot into.
  3. Type 'e' to modify the kernel
  4. Append 'noht' at the end of the line.
  5. Press return key to boot with this options.
  6. Type 'b' to boot to this kernel.

Subscribe to our free e-mail newsletter or RSS feed to get all updates. You can Email this page to a friend.

Related Other Helpful FAQs:

Discussion on This FAQ

  1. concept10 Says:

    What are the pros/cons of disabling HT on P4 CPUs? I currently run Ubuntu 6.10 (Edgy) and the stock config/kernel has Hyper-Threading disabled. How do I enable this? May I enable this in GRUB or do I have to compile another kernel? uname -a > Linux ubuntu 2.6.17-10-generic #2 SMP

  2. nixcraft Says:

    uname -a clearly indicates that you are running SMP kernel. SMP kernel enables HT and dual core support. So you don’t have to do anything.

    To be frank enabling HT will increase your performance. However some application may not work (especially old apps). Those are rare cases and you need to disable HT.

  3. bull Says:

    For any type of server environment HT is beyond worthless. It will degrade your server application performance. HT is meant for interactive DESKTOP applications not DEADLINE based scheduling required by servers.

Leave a Reply

We encourage your comments, and suggestions. But please stay on topic, be polite, and avoid spam. Thank you very much for stopping by our site!

XHTML: You can use these tags: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

*
To prove you're a person (not a spam script), type the security word shown in the picture. Click on the picture to hear an audio file of the word.
Click to hear an audio file of the anti-spam word

Copyright © 2006-2008 nixCraft. All rights reserved - TOS/Disclaimer - Privacy policy - Sitemap - Powered by Open source software.