Kernel Config Questions

static_void · Posted: Mon Apr 07, 2003 8:21 am Post subject: Kernel Config Questions

I already have a running system, but I would like to start playing around with multiple kernels, and I have a few questions regarding the Gentoo_Sources.
What is Low Latency Scheudualing? Do I want it. Under Processor Type and Featurs, what is USer address space size. I have 1 gig ram, do I want to enable High Mem support. What is the Preemtible Kernel? And do I want to COntrol Low Latency with sysctl? Sorry to ask but there was no help for these options in Menuconfig? Also what is GREsecurity, and what would be a good setting for a desktop. What is the Crypto API? Should I enable it? And does the Gentoo kernel have SUPERMOUNT installed in it.? Sorry if is this a lame post and thank you for any answers.
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really · Guru Joined: 27 Aug 2002 Posts: 430 Location: nowhere

michaelb · Posted: Mon Apr 07, 2003 12:31 pm Post subject:

Preemptible kernels and low latency scheduling have to do with how CPUs run code. In a nutshell, OSs these days are multi-process, but CPUs are not. Your CPU can only run one command at a time. So it will grab a chunk of commands to run, work through them, and then set them aside while it grabs another chunk. The 'downtime' while the process blocks are being swapped is called latency. Enabling those two options on a modern architecture should result in an overall performance increase.

Michael
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xcable · Posted: Mon Apr 07, 2003 2:49 pm Post subject: use the built in help

Using the built in help in (xconfig or menuconfig) will tell you alot about a kernel option. In menuconfig highlight the item and press <shift>+<?>, in xconfig press the "help" button (if i remember correctly). Also google the items and read about them, gentoo is all about learning linux.

xcable

Narada · Guru Joined: 12 Dec 2002 Posts: 300 Location: London, UK

Here are my recommendations for gentoo-sources.

1) Low latency scheduling - Yes
2) Control low latency with sysctl - Yes
3) Preemptible kernel support - Yes
4) Supermount removable media support - No
5) High mem support - Yes with setting of 4GB if you have 1GB RAM.
6) GRSecurity - No
7) Crypto - No

1, 2 and 3 are fundamental performance enhancing features and will be available in 2.6 kernel by default and as such should be adopted. 4 results in cd automounting which is unnecessary in my opinion and causes more problems than conveniences. 5 is necessary if you have 1GB of ram with a setting of 4GB. 6 and 7 are unnecessary unless you are running in a production environment, require additional security and know explicitly what you are doing. HTH.
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rajl · Apprentice Joined: 25 Sep 2002 Posts: 287

I have kernel config question of my own. What is the new lzlib library support offered in teh 2.4.20 kernel, and what does it do/why would I want or not want it? I checked the help in the menuconfig, but it just said, no help available at this time.
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Narada · Guru Joined: 12 Dec 2002 Posts: 300 Location: London, UK

Zlib seems to be quite prevalent in the system and I have included it in kernel simply to provide support for it.

http://www.gzip.org/zlib/
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Regor · Posted: Tue Apr 08, 2003 8:16 am Post subject:

razamatan · Apprentice Joined: 28 Feb 2003 Posts: 160

you can easily add