Ottawa Linux Symposium, Day 1
OTTAWA The seventh annual Ottawa Linux Symposium was kicked off by LWN.net's energetic Jonathan Corbet giving his interpretation of the Linux kernel road map. Corbet was followed by Bert Hubert, who spoke about faster boot and application load times.
The official title of Corbet's session was "A 2.6 Kernel road map (as drawn by a blind man)," and he started by quoting Microsoft CEO Steve Ballmer: "There is no road map for Linux," and William Gibson: "The future is here, it's just not widely distributed yet."
Corbet told us that there is indeed a Linux road map, and if you look deep enough, you can find it. So, he said, he looked for it so we wouldn't have to.
He then proceeded to review the history of Linux kernel development with us.
In the "Good Olde Days," as he put it, oddversionnumbered kernel releases were development releases, and evenversionnumbered kernel releases were stable releases. Stable releases were intended and could be expected to work in a production environment, while development kernels were more or less to be used at your own risk.
With this system, feature freezes in an effort to get kernels stable could result in new features in the kernel literally taking years to be actually implemented. Kernel patches could be dropped by those submitting them in the interim and, as a result, the development was not as efficient as it could have been. The lengthy kernel development cycle degenerated into a kind of slushy kernel feature freeze where small features would be implemented, then more small ones until the feature freeze had to be reannounced and reimplemented.
To counteract the long development cycle and the integration of new features being delayed, Linux distributors began to include modified Linux kernels with backported features, making their kernels not necessarily compatible with official kernel.org kernels.
Kernel 2.6.0 was released in December 2003 with bug fix releases about once a month. By OLS of 2004, the kernel was up to 2.6.7, and in the year since it has climbed to 2.6.12. In the first six months of the kernel 2.6 development, an ostensibly stable kernel release, 600,000 lines of code were removed and 900,000 new lines of kernel code were added, representation a replacement of 1/4 of the kernel, said Corbet.
Corbet noted that Linus replaced the virtual memory subsystem in the stable kernel tree last year, calling it an "implementation detail." Kernel 2.7, he explained, is not forthcoming. The development process of 2.6 has evolved into the new development methodology where the current kernel is developed through the mm and release candidate trees, resulting in the socalled "sucker kernels," the 2.6.x.y prerelease kernel trees. In essence, every kernel revision has its own development cycle instead of one larger one for each major kernel version.
Under the evolved process, while Andrew Morton was intended to maintain the stable release while Linus worked on the development release, the opposite has come to pass, with Linus releasing and maintaining the stable kernel releases while Morton manages the development releases. Morton, said Corbet, is bringing professionalism to the Linux kernel development process, offering a voice saying "this is a good patch that is needed, please add comments to it," instead of ignoring it or not getting to it.
Morton, explained Corbet, believes that anyone who takes the time to write a patch for the kernel at the very least deserves a response. The basic philosophy there being that, metaphorically, no one should be kicked out of the kitchen who wants to cook a good meal.
With the changed development system, useful patches are getting into the mainline kernel releases more quickly, and the kernels released by the distributions are increasingly looking like the kernels released by the kernel development teams.
A major reason for the evolution of the development process of the Linux kernel was the advent of BitKeeper, said Corbet. BitKeeper was the first time the Linux kernel development process made use of a source code management system and resulted in no more lost patches. Everything had a place to go and a thorough patch history was introduced.
On April 5, 2005, BitKeeper's provider retracted the free version of the client and forced Linux to find a new management system. Two days later, Linus released git, a quickly written program to have the same effect. Two weeks after that, kernel 2.6.12rc3 was released done entirely on the freshly written git development system.
Corbet's presentation was interrupted by a chipmunk who pretty well stole the show when it scurried around in front of the podium with people trying to take pictures of it standing up to see, as he was discussing git.
A possible alternative to git is mercurial.
What is the future of Linux? Corbet noted even Linus does not have an answer for that. The next kernel, he predicted, would come out in August and include Inotify and kexec, respectively a system for notifying userspace applications about filesystem changes and a system for loading a kernel from within the kernel in emergency situations. The latter is a subject of its own presentation on Thursday.
Corbet spent a good deal of time explaining preemptible kernels and various issues related to scheduling to be addressed in nearfuture kernels.
Upcoming kernels, Corbet expects, will address cluster file systems, FUSE filesystems in user space, software suspend, desktop support, video device support, and a number of other things.
In the area of video device support, a question that is being debated and needs to be answered is who is responsible: X or the kernel? Does the kernel control and configure the graphics card in a Linux system, or does the kernel handle the drivers as it does for all other hardware?
On the security front, the kernel is to get its own contact for security issues. Trusted computing digital rights management support is being implemented for better or for worse in the Linux kernel.
One other issue, Corbet noted, being addressed is the issue of memory fragmentation. Corbet's slide show is available at LWN.net.
In the afternoon, Bert Hubert made a presentation on improving application start times and system boot times.
Using a series of GNUplot graphs, he showed the time delay between disk requests and responses, and where and when the hard drive heads were reading the hard drive. He noted it takes about 20 seconds for Mozilla to load on his laptop, while reading only 20 MB of data, something the disk should be able to do in only one second. The graphs showed the data to be scattered all over the hard drive and the program not reading it in any efficient order, resulting in the hard drive head spending most of its time seeking instead of reading.
Hubert noted that the time it takes a hard drive to move the hard drive head from one place to another on the platter could be put to better use reading several megs of data in the same amount of time. Organizing data more rationally on a hard drive can reduce latency times and improve system performance. Using several similar examples, Hubert demonstrated how applications and sometimes the kernel waste time by not treating the hard drive rationally, in some cases even reading the hard drive backward, which is very slow and inefficient. He is releasing a rough kernel patch to study this to help improve kernel and program performance as far as disk read and write latency.
He noted the Linux's boot cycle can be cut down by 10 seconds on his computer simply by disabling a process called atime, which writes data to disk on boot, resulting in more wasted seek time.
Hubert offered some solutions to the problem of high disk latency, including dumping hard drive data to memory and reading it directly from there, which can cost on reliability if the hard drive and memory versions get out of sync. Other solutions include recording hard drive use patterns and having the hard drive read ahead so that data is preemptively placed into memory before it is needed, resulting in lower latency when it is actually used, and reorganizing binaries on the physical storage media to be loadable more rationally.
The day wrapped up with a reception scheduled for 20:00 sponsored by Intel. Doug Fisher got up to speak around 20:30 while hundreds of attendees milled about feeding on the tray of snacks and drinking the complementary alcohol. They never completely settled down for his talk.
Fisher identified himself as the general manager of Intel's Core Software Division, specifically interested in a development group known as the Open Source Technology Centre (no relation to us, the Open Source Technology Group). Intel, claimed Fisher, uses Linux in their business and contributes back to the Linux community.
He offered a laptop with a 100GB drive and 17" display, in his description, to the first person who could tell him how many Linux servers Intel has deployed. After much uneducated estimating, someone guessed 50,000 Linux servers are deployed at Intel. Fisher called it close enough and gave out the laptop, while claiming 52,000 Linux servers are deployed at the company.
Linux is used for 100 percent of the work involved in the development of new processors at Intel, Fisher stated.
Intel invented the integrated microchip in 1971. The first included 2,600 transistors and had cache memory and I/O directly on the processor for the first time.
Intel's latest processor, he said, boasts 1.72 billion transistors.
The main point of Fisher's presentation was that Intel supports Linux and open source in and throughout its business and contributes back to the community. Over the course of the presentation, he gave out two laptops and two Palm Pilots to members of the audience for answering minor questions of trivia.
When asked if the laptops he was giving out ran Linux, he said "no, but I bet they will within 24 hours." He wrapped up his presentation to the usual polite applause and closed his slide show to reveal the message "Windows XP has locked your desktop," resulting in the single loudest and most sustained booing by nearly everyone present I have ever heard, followed by a member of the audience rushing to the front brandishing a Linux installation CD to widespread applause.
The very last presentation of the evening was by IBM's Art Cannon. His laptop, in contrast to Fisher's, ran Linux, but perhaps demonstrated why Fisher's didn't. After a lengthy battle with X to have an appropriate resolution for the overhead projector, he launched his presentation entitled "How to talk to business people about the value of open source," which sparked the comment of an audience member sitting near me: "not like this."
Problems resolved, Cannon began by explaining that he works in the Sales and Distribution division of IBM and is not a technical person. He told the audience that, in the Linux community, there are two kinds of trust: granted trust, and earned trust. He said he had been granted trust, but was hoping with his talk to earn the trust of the Linux community.
At ISPCon 1998, IBM first indicated a public interest in Linux by posting a penguin on the roof of its booth.
Jon 'maddog' Hall showed up, innocently asking questions of IBM about the stuffed bird on the roof of the booth, testing the company's knowledge and commitment, before identifying himself as the president of Linux International.
Cannon quoted Miguel de Icaza: "How many barrels of oil does our country have to export to pay for the operating system?"
Foreign investment in Linux and open source is largely related back to this fundamental premise.
Venezuela, for example, would take this point of view literally. To pay for a Microsoft Windows license, how many barrels of oil have to be exported?
China, for its part, said Cannon, is intent on joining the World Trade Organization. As part of the process, it has to synchronize its intellectual property laws with other countries and come into line with property rights. To accomplish this, among other things, China would have to legalize its copies of Microsoft software at an estimated cost of $32 billion paid directly to Microsoft in licensing fees. Rather than going through that kind of expense, China chose instead to invest in Linux.
Brazil, thinking along the same lines, announced a threeyear plan to switching 80 percent of its government systems to Linux and funded the project properly to accomplish it.
Cannon wrapped up by reiterating IBM's commitment to release many of its patents to the open source community.
Originally posted to 2005-07-21; reposted here 2019-11-24.
Posted at 12:27 on July 21, 2005
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