modifying the stock arch linux kernel and kernel timer frequency

orlfman · 2015-02-13 17:46:42

so if i understand correctly, if we want to modify the stock arch linux kernel, we have to pull it off of abs. ie "ABSROOT=. abs core/linux" then modify the pkgbuild, uncommenting out make menuconfig and setting the pkgbase name to something different than stock. ie, "linux-custom" then update the checksums followed by importing the gpg keys, ie "gpg --recv-keys 79BE3E4300411886 and gpg --recv-keys 38DBBDC86092693E" for the kernel and patches. then run makepkg -s.

we can't just run make menuconfig on the current kernel that's installed?

and if we pull the linux kernel from abs to customize, does it already come preconfigured with all the arch changes and settings? like its no different than the current one installed?

i just ask because for the most part, i like the current arch kernel, there are just a few minor things i want to change but kept everything else the same as stock arch linux kernel.

also, i herd arch uses 300hz for its timer. whats the benefits and disadvantage of using 300hz over 1000hz for a desktop system?

clfarron4 · 2015-02-13 21:18:48

orlfman wrote:

we can't just run make menuconfig on the current kernel that's installed?

No you can't, because the kernel then has to be compiled so the kernel will run with the different tick rate.

orlfman wrote:

and if we pull the linux kernel from abs to customize, does it already come preconfigured with all the arch changes and settings? like its no different than the current one installed?
i just ask because for the most part, i like the current arch kernel, there are just a few minor things i want to change but kept everything else the same as stock arch linux kernel.

As I understand it from the Wiki, the ABS pulls the PKGBUILD and other arch-specific sources from the ArchLinux script server. However, I don't use the ABS, but pull the files I need directly from the ArchLinux SVN and build using makepkg[1] after making the necessary changes.

orlfman wrote:

Also, I heard arch uses 300hz for its timer. whats the benefits and disadvantage of using 300hz over 1000hz for a desktop system?

You're in for a technical discussion here. This has a reasonably friendly discussion on kernel tick rates.

Basically, higher tick rates = a higher level of timing precision & higher processor load, lower tick rates = lower level of timing precision & lower processor load.

[1] Technically, I use the clean chroot manager package, which is a wrapper for makechrootpkg (which in turn is a wrapper for running makepkg in a clean chroot if I'm not mistaken).

graysky · 2015-02-13 21:24:38

Why do you wanna change the tick rate? I believe the Arch default is tickless anyway. What do you want to achieve with a faster tick rate?

ooo · 2015-02-13 21:25:32

orlfman wrote:

so if i understand correctly, if we want to modify the stock arch linux kernel, we have to pull it off of abs. ie "ABSROOT=. abs core/linux" then modify the pkgbuild, uncommenting out make menuconfig and setting the pkgbase name to something different than stock. ie, "linux-custom" then update the checksums followed by importing the gpg keys, ie "gpg --recv-keys 79BE3E4300411886 and gpg --recv-keys 38DBBDC86092693E" for the kernel and patches. then run makepkg -s.

That's one way to do it, even though I don't think the gpg keys part would be necessary.

we can't just run make menuconfig on the current kernel that's installed?

you need the source code to run make against. The installed kernel only consists of the kernel binary.

and if we pull the linux kernel from abs to customize, does it already come preconfigured with all the arch changes and settings? like its no different than the current one installed?

If you want to copy the arch kernel's configuration. All you need is the .config file from arch kernel package sources, and use it for compiling your own kernel, whether you use ABS or PKGBUILDs or compile the kernel by hand.

Trilby · 2015-02-13 22:05:00

ooo wrote:

If you want to copy the arch kernel's configuration. All you need is the .config file from arch kernel package sources

Not even that. Just unpack it from /proc/config.gz.

FYI:

graysky wrote:

I believe the Arch default is tickless anyway.

$ uname -r
3.18.6-1-ARCH
$ zgrep ^CONFIG_HZ /proc/config.gz 
CONFIG_HZ_300=y
CONFIG_HZ=300

anatolik · 2015-02-13 22:23:18

orlfman wrote:

also, i herd arch uses 300hz for its timer. whats the benefits and disadvantage of using 300hz over 1000hz for a desktop system?

FYI there is also a lot of upstream interest in tickless mode http://lwn.net/Articles/549580/

Arch Linux

#1 2015-02-13 17:46:42

modifying the stock arch linux kernel and kernel timer frequency

#2 2015-02-13 21:18:48

Re: modifying the stock arch linux kernel and kernel timer frequency

#3 2015-02-13 21:24:38

Re: modifying the stock arch linux kernel and kernel timer frequency

#4 2015-02-13 21:25:32

Re: modifying the stock arch linux kernel and kernel timer frequency

#5 2015-02-13 22:05:00

Re: modifying the stock arch linux kernel and kernel timer frequency

#6 2015-02-13 22:23:18

Re: modifying the stock arch linux kernel and kernel timer frequency

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