OLS Day 4

OLS Day 4

After a morning of hacking on random stuff, we went to the sysfs filesystem. Sysfs is a filesystem that is based off of ramfs and is used to display information about the system devices. He went over why the sysfs was created and how he created it. He then explained some of the deficiencies that are in the current implementation of the sysfs. They are currently looking to build a new userspace library for sysfs.

The closing keynote was by Dave Jones, one of Redhat’s kernel leaders. He had some very interesting points on how tools need to be improved in order to make developers much more effective. He showed examples of how Static Code analysis has reduced the number of bugs greatly. He also explained why it is so difficult to regression test the Linux kernel. Jeremy and I are probably going to do tutorials at some point during the semester on doing static code analysis and using code profiling tools. He also had some great ideas about a solution to problems with bugs not getting in the upstream bugzilla’s. I’ll post more on my thoughts on a solution later. Hopefully someone can pick this up for a COSI project this semester.

After the keynote Mark, Sean, Ed and I headed off to dinner before Mark had to catch his flight to England. Tomorrow or next week will be the report on the closing party. Apparently it’s usually pretty wild and out of hand, so this should be very interesting.

OLS 3 (Virtualization Day)

OLS 3 (Virtualization Day)

Went to the Linux Virtualization on Virtual Iron VFE talk. It turned out to basically be and advertisement for Virtual Iron, a company that has written their own virtualization layer that is targeted at corporate data centers. They had some pretty interesting ideas, but they did not seem like they were looking to scale their product up to more than tens of machines and a large portion of their product was closed source with no plans to open source it. I also spent a decent amount of the morning hacking on various little projects with Xen, which should be released shortly.

I was looking forward to going to the talk on Beagle by Jon Trowbridge, but United Airlines screwed up his flight, so he couldn’t make it in, and he couldn’t find someone else to give the talk.

Ed had a pretty amazing comment today. He was surprised at the number of women that are actually attending the conference. There’s probably around ten women here, in a crowd of approximately seven hundred and fiftey developers. Ed’s definitely got a very weird view on women in Computer Science.

In the afternoon the intense Xen presentations started. The first one was presented by Mike Day from IBM on using Xen to Supercharge OS Deployment. He went over how virtual machines make deploying instances of Linux faster because if you create a standard hardware configuration you can automate deployment of your Linux systems. This talk seemed to be geared more towards a system administrator, as he went over several different ways you can normalize your hardware to reduce installation time. One of the problems with reusing filesystems in deployment is that each time it is reused you have to customize parts of the filesystem unless you are using a read only filesystem.

He had some very interesting points on the weaknesses of Xen. These are some of the things that we were starting to address this past Spring with Xenophilia and I am hoping to address even further this fall in some of my work in CS450 and possibly my independent study. Currently there is no mechanism for customizing images as they are deployed, and there is no integration of images with the Xen domain configuration tools. He was thinking about adding scripting support into the domain configuration files to allow the customization of images. They developed a proof of concept, Xen Container Syntax that allowed users to add domain specific configuration information into the domain configuration files. This idea has several problems and is probably going to be reworked from the ground up with support for Xen 3.0. It was written using bash scripting. It’d be interesting if you could use some sort of template or inheritance system to create the domain configuration files. After seeing this presentation I guess I will have to rethink the way I was going to generate customized disk images for when a domain comes up.

The second talk that I attended was a case study of using Usermode Linux to test multiple Linux distributions that was performed by engineers at Intel. It started out with a brief introduction to the LSB. They validated distributions using the runtime tests for the LSB to make sure that the distributions are LSB compliant. He gave a brief introduction to UML, and the guest distribution actually runs as a process in a host. They ran their testing on a 4 Gigahertz Hyperthreaded server with one gigabyte of ram, and two 15,000 RPM SCSI disks.

The next talk was “Testing the Xen Hypervisor and Linux Virtual Machines” by Paul Larson from the LTC. When testing the Hypervisor they were able to reuse many of their tests from testing of the Linux Kernel. They did have to write new tests for the testing of the hypercalls into the hypervisor and they also wrote tests for the tools interface. They created a test interface called Xenfc that is not a systematic test, it randomly generates data to test the hypervisor. This approach has been much more useful in helping developers find corner cases. It was extremely interesting to here some of the ways that they have automated the integration testing of the kernel and hypervisor.

At the Common Virtualization Infrastructure BOF Rik Van Riel discussed some of the new memory management techniques, included page hinting for swapping paging. Problems with over committing pages and having the hypervisor swap the pages to disk was also discussed, but apparently not all architectures can do that at a page granularity level. Currently the hypervisor on s390 has the ability to swap pages. Paravirtualization is also in development at VMWare, and is going to be implemented in their VMWare ESX Server. They are currently working on SMP optimizations, split drivers, and 64 bit support along with a couple of other things. Their system is a non cooperative paravirtualization system, so it’s performance isn’t the best but, it can run transparently.

I also learned of a new addiction Frozen Bubble from Mark Williamson. It’s written in Perl using the SDL module and I’m finding that very scary. There’s also a java port if a game programmed in perl is to scary for you. This is going to make it much more difficult to actually get real work done on xen-get.

The Fedora Foundation is currently being setup after the announcement in the beginning of June. The Foundation is not going to be a subsidiary of Redhat it is probably going to be a Not For Profit Organization with a Board of Directors.

The release schedule was extended due to the non Redhat employees that are now very involved in the release project. They have several big projects on tap for Fedora Core 5 which include:

A rewrite of Anaconda using yum and supporting Xen

A new Fedora Extras build system

A new update notification

Xen 3.0 is possibly on the schedule

A Live CD is a possibility (it has to be created in a sustainable fashion)

GDM early login for FC5

Most of the Stateless Linux changes will be merged for FC5, but it looks like the lab is going to be the test monkeys as their hasn’t been a real deployment yet.

OLS Day 2

OLS Day 2

Our first session of the day was “Write a Real Linux Driver” with Greg Kroah-Hartman. He’s also one of the authors of Linux Device Drivers. The tutorial is writing a driver for a USB temperature probe. The device exports its values to sysfs.

I learned some interesting things about USB. Each USB 2.0 controller also has a USB 1 controller built in and when you plug in a USB 1 device it uses the USB 1 controller. They’ve also got three transfer modes, and one is very similar to UDP networking.

There was a presentation on the state of the Ext3 file system. They are investigating several different possibilities for improving performance and adding new features. They are delaying allocation, performing multiple block allocations, using extents, and switching from using a linked list, to a tree based data structure for their directory data structure.

Some other features that may eventually be implemented in ext3 mainline are increase the file system limit to 8 or 16 Terabytes, make the inode table dynamic, so the number of inodes is not defined at filesystem creation time. The presentation will be on ext2.sourceforge.net. A bit of trivia, there is a bug in a version of fsck with a specific type of corruption that will cause it to run in O(n cubed).

I made it to the Xen Pre Bof where several things were dicussed including support for the new Intel processors, and more extensions to the Xen tools and cleaning them up before the 3.0 release. The security of xfrd transfers was discussed at length, currently they are not encrypted and there is no encryption mechanism. I discussed my plans with several Xen developers about adding a Web Services API using XML-RPC to be used in Xen 3.

OLS Day One

Got to the conference a bit a late after getting lost in the city, and getting off to a bit of a late start. We arrived at the Xen Tech Summit right as Ian was starting his presentation. They’ve got some pretty impressive things marked for Xen 3.0 and 3.1. They include Xen Bus, support for IBM Power processors, Itanium Support, and now support for the 32bit PAE extension. Ian also outlined his three phase plan for the development of the Xen tools.

After the presentation the group split up into smaller groups. I joined the group that was discussing XenStore the new Xen configuration store. Anthony Liguori and Rusty Russell also presented their user level filesystem that allows for the browsing of information in XenStore. This is probably going to be in sysfs.

At the end of the tech summit we made our way over to the registration desk but it was closed. We ended up talking our way into the Intel marketing talk. It was the standard buzz word talk, but there was free food and free booze so what the hell.

After the ridculosly boring talk we ended up at the Highlander Pub for dinner.

Live 8

Made the long road trip to Philly on Friday afternoon to go see Live 8 on Saturday. It was an awesome show and definitely worth the trip. I’ll have some of the pictures that have actually turned out posted in the next couple of weeks. I did manage to fight my way through the crowd up to the first big screen.

Hopefully George W actually gets the message, but he’s not exactly the sharpest knife in the drawer so who knows. In other random stuff I did manage to wake up early enough to go see the Liberty Bell and Independence Hall (I’ve got some pictures of that to)