Download your favorite Linux distribution at LQ ISO.
Go Back > Forums > Linux Forums > Linux - Software > Linux - Kernel
User Name
Linux - Kernel This forum is for all discussion relating to the Linux kernel.


  Search this Thread
Old 07-13-2007, 01:06 PM   #1
LQ Newbie
Registered: Jul 2007
Location: Atlanta Area, GA, USA
Distribution: CentOS/RH/Debian
Posts: 24

Rep: Reputation: 0
Post linux 2.6.21: Timer Frequency / Preempt

I'm building a 2.6.21 kernel for a 2-core 64-bit-capable i386 system. Specifics are: Pentium D 805, with 1gb of RAM. No ISA or PCI-Express. Sata present but unused. I will be running this as a desktop and it will be doing a variety of things: number crunching, compiling, media creation, media playback, gaming, etc.

What should I pick for a timer frequency? the help only mentions 250mhz and 300mhz, makes no mention of the slower setting and the 1ghz setting.

I would also like to know if I should choose voluntary-preempt or fully-preemtable.

These are all settings that are new to me, as the last kernel I built was 2.4 and the built-in help doesn't really tell why one would use the other settings, only in very specific cases to they outright say "you want that if you do this"

Is there a better place to find answers to this kind of thing?
Old 07-13-2007, 03:42 PM   #2
Registered: Feb 2002
Location: Grenoble
Distribution: Debian
Posts: 9,571

Rep: Reputation: 180Reputation: 180
Do you mean that option where you have 100Hz, 1000Hz, 250Hz and so on? Note that it's Hz, not MHz. The parameter specifies how often the timer interrupt runs. The higher the number, the more responsive the system potentially is. It uses more time every second in the timer routine, so higher number means (small) performance degradation. Note that, if I remember correctly, previous kernel versions used 100Hz and that was fine. Higher value is for real-time tasks and high responsibility. Normal user will rather not notice it.

You can also safely choose voluntary-preempt. The difference is in the number of places when switching can take place. When the kernel is not fully preemtable, certain passages may still use the processor when there's someone with better reason for it. As in the previous example, most users will not usually notice. Full preemption is designed for real-time systems. It brings an extra level of complication in certain places. If you do not have a clear reason to use it, you probably do not need it.


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Multimedia timer (SMP friendly timer) bigqueso Linux - Kernel 0 03-15-2007 03:49 PM
[KERNEL] 2.6 preempt no smooth audio? mritch Linux - General 2 11-24-2004 12:25 AM
Preemptible Kernel (PREEMPT)---yes or no? ganja_guru Linux - Software 8 09-05-2004 11:29 AM
Slack10 2.4.26 w/ Preempt and ALSA shadyvlad Slackware 1 08-18-2004 01:49 PM
Whitepaper: Preempt v. Low-Latency Patch jeremy Linux - General 1 03-22-2002 02:07 PM > Forums > Linux Forums > Linux - Software > Linux - Kernel

All times are GMT -5. The time now is 01:20 AM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration