Pete and Jono had a Kernel Q&A on #ubuntu-meeting. Since the IRC logs are not so readable and split across pages, I would like to turn it into a readable format.

Text in [] Includes my comments or links

UndiFineD: What is the impact on performance on the BLK removal?

Should be a positive impact, and will make things more maintainable long term, will be more noticeable on multi-core boxes

kim0: Does Ubuntu server have certain tweaks applied to its kernel vs desktop

The only real tweaks are a few config settings and the increase on the number of CPUs the kernel supports and the default IO scheduler is Deadline

OkDucky: Why does the performance of ubuntu (10.10) reduce a fair bit when under heavy hdd load? is there work being done to improve this? (it could just be my hardware of course..)

 The IO Scheduler for 2.6.38 has been revamped so you should start to see better performance

Taek: How exactly does the glorified 200 lines kernel patch will benefit in 11.04

That is the auto cgroup stuff, isolate session tasks, it helps balance the load and will help increase performance. Bottom line is you will see a benefit on heavy IO

m4n1sh: What about btrfs? When is it going to be in a usable situation fit for default install?

Post 11.04 we are expecting it to shore up to be a default, right now its in the installer but you have to manually select it

sebsebseb: What are the main features of the next kernel?

Look at kernelnewbies.org for the 2.6.38 kernel, way to many to list here [*]

Also look at the A2 release notes some more info there as well.

Jay-Cee: Any improvements with btrfs performance?

File deletion is noticeable faster, but as with any dev system things are in flux

Tach: Will there be any fixes with the issues with input of some joysticks being detected as mouse input. An example of such an issue is here

Not sure this is an edev issue with X, not kernel per se

m4n1sh: Lennart posted a 2 line solution for the glorified 200 lines patch for kernel. Was Lennart’s solution better than that of kernel?

Lennart’s solution had a limited use case and was not general purpose unfortunately

m4n1sh: I heard that installing ubuntu using btrfs as FS takes some hours to install. Is it true? Any special reason for this problem (provided it is true)

That used to be the case, more recent versions of the kernel have fixed that specific issue afaik

kim0: How does the server’s kernel compare to other enterprise distros’ kernels , i.e. does the team regularly sync drivers for Enterprise grade cards (SAS, NICs, LOMs…)

So this is a multipart answer so bear with me while I type it out. We have a pkg call LBM that get updates on a few drivers (LBM == Linux Backport Modules). We also have for LTS releases backported kernels that have the latest in upstream hardware enablement. The kernels are call LTS Backport Kernels and are basically the latest release kernel running on the last LTS. Keep in mind this is NOT A DESKTOP feature. It is only supported on the server flavor. So yes we have some level between the two to refresh drivers for servers. 

m4n1sh: The problems with suspend/resume/hibernate lies in which part of the kernel? Is the situation improving?

We have a tool call fwts (in universe) that will test your bios and tell you what is broken. Run that if you are having issues then attach the out put when you file a bug. It will help us determine if its a true kernel issue (rare) or a broken BIOS

doctormo: What should you do if a kernel bug makes ubuntu unstable for a target machine? downgrade kernel or downgrade os?

Downgrade the kernel, way easier

Taek: Is there plans or even talk about having a system update without having to restart or install third party software such as ksplice.

The kernel will support kplice however we have no plans to do such a thing, there is already a commercial venture. That does that.

doctormo: Is there any plan to help move packages from module-assistant to dkms in debian/ubuntu?

There are no plans to do so, dkms is our preferred method for out of tree drivers

GauravButola: There are wirless modems (wireless broadband data cards) and TV tuner cards, which do not get detected by Ubuntu at all. What can I expect in 11.04 in this respect.

The biggest reason is that the firmware is not available or there is not a driver. If the firmware is available and we don’t have it file a bug and we will see what we can do to get it into the distro. As far as what to expect, there is better support based on bugs and user feedback.

doctormo: Does hard coding usb and pci ids into the kernel driver code make enabeling hardware that would work, but for a new id, more difficult?

It is harder but its the only way we have right now, device tree should fix this problem in the future but its not ready for prime time on X86

sebsebseb: I don’t really know much about USB 3.0, but when is Ubuntu likely to support it?

It entered the kernel in 2.6.35 iirc and has been in ubuntu. Older ubuntu kernels will get support as it bubbles into the stable tree from upstream

doctormo: Are there any automated kernel speed tests happening in order to improve perforance in the kernel?

Not currently, there are plans but that is more of a QA question (hint ask marjo on his turn). However there are other doing it

sebsebseb: Do you think Ubuntu 11.10 will use BTRFS by default, if so why?

At this point we have no idea, that will be determined based on stability at UDS