Linux v2.6 Begins Testing

xose quotes Linus from the kernel list: "the naming should be familiar - it's the same deal as with 2.4.0. One difference is that while 2.4.0 took about 7 months from the pre1 to the final release, I hope (and believe) that we have fewer issues facing us in the current 2.6.0. But very obviously there are going to be a few test-releases before the real thing. The point of the test versions is to make more people realize that they need testing and get some straggling developers realizing that it's too late to worry about the next big feature. I'm hoping that Linux vendors will start offering the test kernels as installation alternatives, and do things like make upgrade internal machines, so that when the real 2.6.0 does happen, we're all set." You all know what to do ;) Update: 07/14 17:49 GMT by S : OverNeith writes "Joe Pranevich has done it again! He's written another summary document on what to expect in the new and upcoming 2.6 Kernel!"

Comments

Re:Difference?

[pe1rxq]

The biggest change for normal users is the preempt patch, it will make your system very responsive to interactive tasks (ie a graphical desktop) also the new schedulers should help here.

Jeroen

Re:This is a big deal.

[avalys]

You don't have to wait - pretty much all of big stuff has already happened in the 2.5 series. 2.6 is the next stable series, which (usually) means no big architectural changes. What's going on now is testing to ensure that the 2.5 series is stable enough to be considered for a release as "2.6.0".

Re:I got it before the /.ing

[bumby]

For example. /dev/hda, /dev/hdb/, /dev/hdc now become /dev/discs/disc0, /dev/discs/disc1, /dev/discs/disc2

That is called devfs, and as far as I know is an optional thing. At least it was in 2.4-series, and I really really doubt it isn't in 2.5 and will be in 2.6. So just skipp the CONFIG_DEVFS_FS and CONFIG_DEVFS_MOUNT and use your old nodes.

Re:Difference?

[Libor Vanek]

And better USB support with easier way for writing drivers for various USB gadgets.

Re:This is a big deal.

[sfraggle]

I personally can't wait to skim the change logs.

Kernelnewbies.org has a page which usefully summarises the new stuff in 2.6.

Re:Sorry

[Surak]

Actually, it *is*. It's in the portage tree under sys-kernel/development-sources development-sources-2.6.0_beta1.ebuild

Re:Difference?

[inode_buddha]

Yes, IPSEC is already in 2.5.xx, along with the NSA's SELINUX hooks, IBM's JFS filesystem, and SGI's XFS filesystem. Lots of VM and block I/O work, too.

Re:timeslice and 'hyperthreading'??

[nilsjuergens]

Replying to point (2):

The scheduler in 2.6.xx is hyperthreading-aware.
It knows that switching a process from one hyperthread to another on the same cpu is less expensive than switching to another physical cpu (becaus both first- and second-level cache reside on-die), but it also tries to balance load on physical cpus.

While >=2.4.19 supported hypterthreading up to a certain point it happend that two processes were running on the same cpu while the other (physical) cpu was running idle. This does not happen with the new ht-aware scheduler.

Look here for a (compressed) version of the initial discussion.

word of warning

[Maimun]

According to Alan Cox, there are security issues with 2.5.* (and thus with 2.6-test1)

Last time I checked there were remote DoS attacks and local root attacks present in 2.5.7x

See:

Re: Linux v2.6.0-test1

The whole thread is here Linux v2.6.0-test1

Re:BIO

[kill-1]

From Dave Jones' write-up (link in the post above)

CD Recording.
~~~~~~~~~~~~~
- Jens Axboe added the ability to use DMA for writing CDs on ATAPI devices. Writing CDs should be much faster than it was in 2.4, and also less prone to buffer underruns and the like.
- Updated cdrecord in rpm and tar.gz can be found at *.kernel.org/pub/linux/kernel/people/axboe/tools/
- With the above tools, you also no longer need ide-scsi in order to use an IDE CD writer.
- Ripping audio tracks off of CDs now also uses DMA and should be notably faster. You can also find an updated cdda2wav at the same location.
- Send good/bad reports of audio extraction with cdda2wav and burning with the modified cdrecord to Jens Axboe
- Currently only 'open by device name' works in cdrecord. cdrecord -dev=/dev/hdX -inq
- More info at http://lwn.net/Articles/13538/ & http://lwn.net/Articles/13160/

Still the same problems since 2.5.68

[hacker]

2.6.0-test1 is MUCH slower than 2.4.21 or 2.4.21-preempt-rml here. I see that the timing issues are still not fixed in 2.6.0-test1, and haven't been working since 2.5.68. I've reported this at least a dozen times to the appropriate people, with no fixes eminent yet.

To test this issue out, run Sawfish, and bind a key like Ctrl-Alt-B to a black-background xterm. Launch X, and run Sawfish. Hit Ctrl-Alt-B once and see what happens. It's consistant here across about 6 machines, all different hardware.. a 3-4 second delay, then anywhere from none to 4 xterms will open up. On 2.4.anything, it opens the xterm instantly, and only opens one of them, not 3, not none.

The other issue is that there's some underlying change in the TCP stack/net drivers that cause rsync and anything running over ssh/ipsec to fail with weird dropped-socket errors from the applications using them. Again, on 2.4, it works flawlessly.

It's very annoying, and both of these are blockers for me and most of the machines I'd be running this on. It happens with anything that involves keyboard shortcuts; menu accels, launched applications, keybindings, everything.

Changing to the different schedulers does not help; deadline, as, or cfq. 2.5.68 worked perfectly, and didn't have these anomalies, but every single kernel since that time, has had it. I've diffed, and I can't tell which of the dozens of changes actually broke this.

If anyone has a solution, I'm all ears.