# Repo-ck

Related articles

- Linux-ck
- Linux-ck/Changelog

Article details setup and usage of an unofficial Arch Linux repo containing generic and CPU-optimized kernel and support packages containing the ck1 patchset featuring the Brain Fuck Scheduler by Con Kolivas.

## Packages in repo-ck

### Kernels and related packages

The repo contains generic packages as well as CPU-specific packages for the linux-ck family. Many Arch users are familiar with the concept of a generic kernel package. The official Arch kernel is available in two flavors (either i686 or x86_64) which are generic packages in that i686 will work with any compatible x86 CPU and x86_64 will work with any compatible x86_64 CPU. Users have a choice between the corresponding generic linux-ck packages or CPU-specific and optimized linux-ck packages:

CPU Type | Group Alias | Details
--- | --- | ---
Generic | ck-generic | Compiled with generic optimizations suitable for any compatible CPU just like the official Arch linux package. This is true for both Intel and AMD processors.
Intel | ck-atom | Intel Atom platform specific optimizations. Intel Atom CPUs have an in-order pipelining architecture and thus can benefit from accordingly optimized code.
ck-core2 | Intel Core 2-family including Dual and Quads (Core 2/Newer Xeon/Mobile Celeron based on Core2).
ck-nehalem | Intel 1st Generation Core i3/i5/i7-family specific optimizations.
ck-sandybridge | Intel 2nd Generation Core i3/i5/i7-family specific optimizations.
ck-ivybridge | Intel 3rd Generation Core i3/i5/i7-family specific optimizations.
ck-haswell | Intel 4th Generation Core i3/i5/i7-family specific optimizations.
ck-p4 | Intel Pentium-4 specific optimizations (P4/P4-based Celeron/Pentium-4 M/Older Xeon).
ck-pentm | Intel Pentium-M specific optimizations (Pentium-M notebook chips/not Pentium-4 M).
AMD | ck-kx | AMD K7/K8-family specific optimizations.
ck-k10 | AMD K10-family specific optimizations including: 61xx Eight-Core Magny-Cours, Athlon X2 7x50, Phenom X3/X4/II, Athlon II X2/X3/X4, or Turion II-family processor.
ck-barcelona | CPUs based on AMD Family 10h cores with x86-64 instruction set support.
ck-bobcat | CPUs based on AMD Family 14h cores with x86-64 instruction set support.
ck-bulldozer | CPUs based on AMD Family 15h cores with x86-64 instruction set support.
ck-piledriver | CPUs based on AMD Family 15h cores with x86-64 instruction set support.

CPU-specific optimization are invoked at compilation by selecting the corresponding option under Processor type and features>Processor family or by setting-up the .config file accordingly. These changes setup make specific gcc options including the $CFLAGS.

### Miscellaneous packages

Repo-ck also contains pre-compiled packages for chromium-scroll-pixels and for chromium-no-sse2.

CPU Type | Package | Details
--- | --- | ---
Generic | chromium-scroll-pixels | Chromium browser patched to maintain the `--scroll-pixel` functionality allowing users to set the speed of their wheel mouse's scrolling functions.
chromium-no-sse2 | Chromium browser patched to allow hardware without the SSE2 instruction set to run chromium.

## Setup

Add the repo-ck repository into `pacman.conf` and sign Graysky's key.

## Installation examples

Use the ck-X group and select the desired packages for installation. There are 6 groups corresponding to the 13 package sets: ck-generic, ck-atom, ck-core2, ck-nehalem, ck-sandybridge, ck-ivybridge, ck-haswell, ck-p4, ck-pentm, ck-kx, ck-k10, ck-barcelona, ck-bulldozer, ck-piledriver

    # pacman -S ck-generic
    :: There are 7 members in group ck-generic:
    :: Repository repo-ck
       1) broadcom-wl-ck  2) linux-ck  3) linux-ck-headers  4) nvidia-304xx-ck  5) nvidia-ck
       6) virtualbox-ck-guest-modules  7) virtualbox-ck-host-modules

    Enter a selection (default=all):

Alternatively, simply direct pacman to install the packages directly:

    # pacman -S linux-ck linux-ck-headers

## How to determine which CPU optimized package set to select

Users unsure which package set to use can always install the ck-generic group which will drive any compatible CPU. For those wanting CPU-specific optimized packages, run the following command (assuming that base-devel is installed):

    # gcc -c -Q -march=native --help=target | grep march

The resulting value is what gcc would use as the march CFLAG. Refer to the table below for a mapping of this value to the correct group.

Note: This table has been updated to show the new simplified march options that ship with gcc v4.9+, for more see the release notes for this release.

Brand | Group | March
--- | --- | ---
Intel | ck-atom | bonnell
ck-core2 | core2
ck-nehalem | nehalem
ck-sandybridge | sandybridge
ck-ivybridge | ivybridge
ck-haswell | haswell
ck-p4 | pentium4, nocona
ck-pentm | pentm, pentium-m
AMD | ck-kx | athlon, athlon-4, athlon-tbird, athlon-mp, athlon-xp, k8-sse3
ck-k10 | amdfam10
ck-barcelona | barcelona
ck-bobcat | btver1
ck-bulldozer | bdver1
ck-piledriver | bdver2

Note: Users are encouraged to add additional entries to this table based on their experience.

Additional links can be used to help determine which package set to select:

- http://wiki.gentoo.org/wiki/Safe_CFLAGS#Intel
- http://wiki.gentoo.org/wiki/Safe_CFLAGS#AMD
- http://www.linuxforge.net/docs/linux/linux-gcc.php
- http://gcc.gnu.org/onlinedocs/gcc/i386-and-x86_002d64-Options.html

## How much faster are the CPU optimized packages

The answer is not that much faster. Extensive testing comparing the effect of gcc compile options on resulting binaries have been conducted by others with varying result from no change to rather significant speed ups.

- phoronix labs
- Kernel patch for more CPU families offers measurable speed increases.

Readers are encouraged to add to this list.

## How to enable the BFQ I/O scheduler

Since release 3.0.4-2, the BFQ patchset is applied to the package by default. Users must enable the BFQ scheduler to use it; it is dormant by default.

### Globally (for all devices)

Add `elevator=bfq` to boot loader Kernel parameters.

Note: Users building the PKG from the AUR have an option in the PKGBUILD itself to globally use the BFQ as the default I/O scheduler.

### Selectively (for only specified devices)

Direct the kernel to use it on a device-by-device basis. For example, to enable it for `/dev/sda` simply:

    # echo bfq > /sys/block/sda/queue/scheduler

To confirm, simply cat the same file:

    # cat /sys/block/sda/queue/scheduler
    noop deadline cfq [bfq]

Setting this way will not survive a reboot. To make the change automatically at the next system boot, create the following tmpfile where "X" is the letter for the SSD device.

    /etc/tmpfiles.d/set_IO_scheduler.conf

    w /sys/block/sdX/queue/scheduler - - - - noop

## Package trivia/repository statistics

Repo statistics are available (popularity of packages, which CPU is most popular, # of downloads, etc.).

Note: The statistics are not updated daily but do give a snapshot of the data.

## Troubleshooting

### Forum support

Please use this discussion thread to voice comments, questions, suggestions, requests, etc. Note from graysky, "I can add other CPU-specific builds upon request. I just wanna be sure people will actually use them if I take the time to compile them."

### Downloads interrupt regularly

See [1]. Change the pacman downloader to wget, which automatically resumes downloads.

Category:

- Kernel