Comparison between Fedora and Ubuntu Kernel

JoshBoyer in red hat is curious about comparing the different configurations of Kernel3.8 in Fedora18 and Ubuntu13.04, and finds some interesting points. Note: In the following illustration, JoshBoyer selects the linux-image-3.8.0-19-generic of 3.8.11-200. fc6 and Ubuntu13.04 in Fedora18 in X86 respectively.

Red Hat Josh Boyer is curious about comparing the different configurations of the Kernel 13.04 carried by Fedora 18 and Ubuntu 3.8, and finds some interesting places.

Note:The following is an illustration

Josh Boyer compared the linux-image-3.8.0-19-generic in the current 3.8.11-200. fc6 and Ubuntu 13.04 in the X86 64-bit environment, respectively, using the same upstream kernel.

Underlying settings

Ubuntu sets the maximum number of available Kernels to 256 while Fedora is only 128. At the same time, Ubuntu enables more NUMA (non-consistent Memory Access) Support and sets a higher number of NUMA support. Considering that Canonical intends to unify the kernel in Ubuntu Desktop and server versions, it is completely understandable for Ubuntu to enable these SMP-related options.

Set Fedora to 1000 and Ubuntu to 250 on the number of wake-up attempts of timer interruptions. Generally, a large value means faster interaction and response, which is more suitable for desktop applications. A smaller value makes it easier for the server to focus more on the work, rather than response interruption. However, both enable on-demand response, and the CPU will not be disturbed by useless timers when idle. In the future, it is estimated that both will gradually migrate to the zero timer wake-up introduced by the 3.10 kernel to better reduce energy consumption during sleep.

At the same time, Ubuntu also enables the quick without HZ option by default, which increases the chance that the kernel enters idle state and reduces energy consumption. Fedora was enabled when this option was just introduced to upstream, but it was disabled due to many problems in the future. After several kernel revisions, this feature is much more stable than it was at the beginning and deserves further consideration.

Default

The default I/O scheduler of Ubuntu is deadline, while the Fedora is CFQ (Completely Fair Queueing ).

In terms of the default CPU frequency control policy, Fedora follows the regular on-demand control, while Ubuntu has a slightly heterogeneous performance priority.

However, both of these items can be adjusted at runtime. Here we only refer to the default settings.

Linux Security Module

Fedora was not surprised to only enable support for SELinux in the kernel.

Ubuntu enables the support of all security modules more "friendly" than the AppArmor supported by default. Although this does not bring any security improvements, it gives the system administrator more options than the default security module.

Module Signature

Both Fedora and Ubuntu use module signatures, but there are differences in specific applications.

Fedora uses SHA256 for module signature, because this is a common verification method used by UEFI.

Ubuntu uses the module version. when loading the module, compare its CRC with the records in the kernel to determine whether the module is secure. At the same time, Ubuntu also enables the "source version" field, which allows compiling and Loading modules for different kernel versions to a certain extent, if you know the corresponding relationship clearly.

Legacy System Support

Compared with Fedora, Ubuntu enables more support for devices, partitions, and networks that are rarely seen or abandoned, such as atari and sysv68 partitions, DECNET and ARCNET networks, and parallel IDE interfaces (Editor's note: linux uses the SATA driver to support IDE eight years ago ). However, Fedora also enables support for some legacy systems, such as OSS, and Ubuntu has completely disabled it.

In addition, the Ubuntu kernel also enables more SoC support by default, such as keyboards, GPIOLIB, and MFD drivers that can be seen in various embedded fields, as well as JFFS2 and F2FS file systems. This seems to be inconsistent with what Canonical says about the combination of desktop and server versions (Editor's note: Maybe I want to get involved in X86 embedded ?), However, this also means that Ubuntu may be enabled on some rare X86 SoC devices.

In terms of Open-Source graphics card driver support, Fedora only enables those that support KMS and a small number of FB drivers, while Ubuntu enables almost all of them by default.

At last, Ubuntu enables many kernel drivers in the Staging state by default. Staging stores open-source drivers that cannot enter the main line maintenance due to quality problems. Enabling it may bring more extensive hardware support, but it also brings potential risks to system stability due to quality.

Summary

There is no significant difference in performance between the two kernels, but some of the details are worth review.

For more information about Ubuntu, see Ubuntu special page http://www.linuxidc.com/topicnews.aspx? Tid = 2

For more information about Fedora, see Fedora topics page http://www.linuxidc.com/topicnews.aspx? Tid = 5