2.6 kernel maintainer Andrew Morton [interview] released 2.6.0-test9-mm1. He notes the following changes:
A couple of fixes for VM memory reclaim. Finalized the ia32 EFI code. Potentially fixed the IO scheduler regressions. Dropped the runtime-selectable-IO-scheduler patches. Several fixes to the pagecache readahead code, improving performance under "seeky workloads" such as non-direct-io databases.
Read on for the full changelog.
I'm giving 2.6.0-test9 a go, but I'm having some trouble with my IDE (ATAPI) CD-R drive. I can't get it to read without error, and I can't get it to write without error.
This is on x86 with a 2.6.0-test9 vanilla kernel. Using DMA doesn't seem to effect it. The drive fails to read with or without it.
Has anyone else had luck with the ide-cd driver and the ATAPI interface? Is this a known issue? Does anyone have any suggestions to get this working?
"OK, I have incorporated comments. If everyone could try to keep your entries on the list up to date it would be nice. It might give you a bit more bargaining power to get things in."
He goes on to point out that the lists may not be realistic, that 2.6.0 will likely be released prior to the lists being cleared. Nick also highlights a comment made by Alan Cox [interview] who said, "Someone also needs to go fix all the 2.4 security holes still in 2.6 last time I checked - things like the execve holes and execve versus proc races." Read on to see the latest must-fix and should-fix lists.
Mike Benoit recently posted a link to results from his new and improved file system shootout, using better hardware and running more tests. Using two benchmarks that are designed to measure hard drive and file system performance, Bonnie++ and IOZone, he's compared a number journaling filesystems found in the 2.6 kernel [forum]. Included in the lineup are EXT2 (not journaling, but an effective baseline [story]), JFS, XFS, ReiserFS, Reiser4, and EXT3 each compared head to head on both SCSI and IDE drives.
In Mike's summary he labels JFS and XFS as 'best bang for your buck' explaining, "While not the fastest file systems, both of them consistently perform close to EXT2, while using minimal CPU. XFS seems to be faster over a wider range of benchmarks, however it does use slightly more CPU than JFS. While JFS really starts to slow down with lots of files." As for pure speed, Mike points to Reiser4 which really shined in the Bonnie++ benchmarks, though not quite so much in the IOZone benchmarks. He suggests, "ReiserFS v4 will [definitely] be worth while keeping an eye on, especially considering some of the exciting new features it offers."
Nick Piggin [interview] posted v17 of his scheduler patches, saying, "Still working on SMP and NUMA". Highlights of his recent work include:
"Sequential CPU balancing so you don't get a big storm of balances
every 1/4s. Balancing is trying to err more on the side of caution, I have to start analysing it more thoroughly though. Attacked the NUMA balancing code. There should now be less buslocked ops cache pingpongs in some fastpaths. Volanomark likes it, more realistic loads won't improve so much"
Read on for the full changelog.
Con Kolivas [interview] posted an updated version of his Swappiness Autoregulation patch [story], this time "done the right way (tm)". Instead of updating swappiness at every tick (which is either 100 or 1000 or 1024 times per second, depending on architecture) the swappiness is updated only when there is pressure to swap. This has the double benefit of avoiding a possible divide-by-zero error, and reduced overhead. It also makes swappiness read-only to user-space.
Linux creator Linus Torvalds has released 2.6.0-test9, weighing in as a 120kB compressed patch about which he says, "[this] is small for a week of work, but is still more than I want to see before a stable release." He goes on to stress the importance of the stability freeze, "I'm going to _totally_ ignore patches that aren't for major bugs. Don't send me anything that _others_ wouldn't consider horribly critical." That said, it looks like we can expect a Halloween release of 2.6.0-test10, at which time Linus is intending to hand the tree to Andrew Morton [interview], adding, "and if he takes it we'll probably have a real 2.6.0 after a final shakedown. So try to help, please. We'll all be happier."
The latest patch includes XFS and cifs updates, justified as "they were pretty benign and largely just bugfixes". Added with this patch was the recently GPL'd Promise SATA driver still flagged as 'experimental' with the comment, "which you either disable or which allows people to use modern hardware."
Read on for the full changelog, as well as some of the resulting discussion.
Con Kolivas [interview] strikes again, this time with a patch that regulates the VM subsystem's "swappiness" on-the-fly, depending on the percent of RAM being used by applications (it does not take disk cache into account). Con explained the effects of this patch:
"This has the effect of preventing applications from being swapped out if the ram is filling up with cached data. Conversely, if many applications are in ram the swappiness increases which means the application currently in use gets to stay in physical ram while other less used applications are swapped out.
"For desktop enthusiasts this means if you are copying large files around like ISO images or leave your machine unattended for a while it will not swap out your applications. Conversely if the machine has a lot of applications currently loaded it will give the currently running applications preference and swap out the less used ones."
Swappiness is a kernel "knob" (located in /proc/sys/vm/swappiness) used to tweak how much the kernel favors swap over RAM; high swappiness means the kernel will swap out a lot, and low swappiness means the kernel will try not to use swap space.
Update: Con posted an updated version of the patch.
2.4 stable kernel maintainer Marcelo Tosatti released 2.4.23-pre8 with the following comments:
"Here goes -pre8... It contains a quite big amount of ACPI fixes, networking changes, network driver changes, few IDE fixes, SPARC merge, SH merge, tmpfs fixes, NFS fixes, important VM typo fix, amongst others. People seeing boot IDE related crashes on Alpha with previous kernels
please try this.
Read on for the complete changelog.
The 2.4.23-pre series has seen a number of criticial changes to how the VM functions. Linux 2.4 stable kernel [forum] maintainer Marcelo Tosatti merged some key portions of Andrea Arcangeli's -aa patches [forum] in 2.4.23-pre4 [story] and 2.4.23-pre5 [story], also removing the much debated OOM-killer with mixed results [story]. Linux laptop users will probably look forward to the final release of 2.4.23 due to the merging of Jens Axboe's "laptop-mode" patch [story] in 2.4.23-pre7 [story], aiming to increase battery time.
In a recent email forwarded to the lkml, Neil Brown confirmed that his testing with 2.4.23-pre7 showed the recent -aa merge has improved HIGHMEM support. He summarizes, "24 hours later, 2.4.23-pre7 is running very happily using all 4Gig of RAM and not showing any inappropriate pressure on the dentry cache." We can expect to start seeing 2.4.23 release candidates some time in November.