LKML Summary Podcast

Audio: COMING SOON

For Thursday, October 1st, 2009, I’m Jon Masters with a summary of today’s LKML traffic.

In today’s issue: concurrent workqueues, DRBD, VFAT, and writeable overlays.

Concurrent workqueues. Tejun Heo posted an RFC patch series implementing concurrency managed workqueues. The basic premise is that having such an implementation in the kernel keeps the individual workers from having to do it for themselves. The implementation adds a single shared pool of workers per cpu and will attempt to keep the CPU loaded up with as much deadlock-free work as is possible. The code is quite intrusive, illimating RT support from workqueues and touching a lot of code (including the scheduler) but Tejun thinks that, overall complexity will decrease and other code could be removed. David Howells was interested in how this might replace slow-work, and he posted some followup questions for Tejun.

DRBD. “Roland” (devzero) mailed concerning recent comments surrounding DRBD, the distributed replicating block device. He was concerned because a number of people have expressed an interest in these patches not being merged, while DRBD has already been out of tree for around 8 years, and isn’t in staging. He would like to see some more satisfactory resolution for “brilliant things like these” than have them perenially sit out of tree while folks figure out the best way to effect a dm/md merge and a timeframe thereof.

VFAT. Philippe De Muter followed up surrounding his “Simon and Garfunkel” issues (that mp3 files with two tailing dots before the extension were not being properly handled) on VFAT filesystems to say that a recent Windows box wasn’t handling this all too well either. He considers this a bug and isn’t sure that Linux should remain compatible with it, so withdraws his request.

Writeable overlays. Val Aurora posted the latest version of her union mounts and writeable overlays design document, complete with a bunch of patches that she has rebased to kernel 2.6.31, and accompanying tools patches to e2fsprogs and util-linux-ng. Apparently, there will be some review patches soon, though that isn’t an excuse not to start poking. The patches are up at http://valerieaurora.org/union/.

In today’s pull requests: some scheduler fixes from Ingo Molnar (freshly back from a trip, and now believing that it’s “good in all tests”), some networking updates from David Miller, some m68knommu updates from Greg Ungerer, some wireless updates from John Linville, and some btrfs updates from Chris Mason.

In today’s miscellaneous items: a question as to whether IA64 should use a global register for storing per-cpu pointers from Tony Luck, some netfilter patches from Joe Perches, ongoing discussion of alternatives support for cmpxchng64 (silent failure on a cmpxchg of unsupported size annoys Linus, who also provides a commentary on Windows NT’s cmpxcnhg implementation), some autofs4 patches from Ian Kent, version 5 of a fix for too big f_pos handling from Kamezawa Hiroyuki, a suggestion that there might be a buggy implementation in ftrace_profile_enable_event from Paul Mackerras, a series of patches intending to correct usage of __exit_p and __devexit_p from Uwe Kleine-Konig, version 20 of the swap over NFS patches originally worked on by Peter Zijlstra (who is short on time) and now being persued by Suresh Jayaraman, a small update to the optimization flags for the AMD Geode from Matteo Croce, a question about connector and PROC_EVENTS behavior from Kevin Fox, some Kconfig comments cleanups from Michael Roth, and some wonderings from David Miller about the status of mvalloc_user and “perf” mmap patches needed for SPARC to make use of performance events utilities properly.

Finally today, Arjan van de Ven and Andrew Morton continued to discuss the state of the Linux floppy driver, in particular that fact that GCC complains that floppy.c’s ioctl has insufficient bound checks. In response, Andrew stated: ‘gad. You said “floppy” and “ioctl” in the same sentence. Where angels fear to tread.” Separately, Andrew sent an additional error handling patch.

In today’s announcements: The Linux Foundation Technical Advisory Board. James Bottomley posted to let everyone know that there will be elections for the board of the Linux Foundation Technical Advisory Board (TAB) immediately following the forthcoming events in Japan (2009 Kernel Summit and Japan Linux Symposium). Anyone can stand for election by emailing as advised.

Clownix-spy. Vincent Perrier posted to announce a utility at clownix.net that can be used to plot any kernel variable changing over time through the use of a periodic kernel thread that wakes up to sample it and deliver the results to a userspace gtk-based plotting tool. The initial example is for plotting qdisc enqueus, dequeues, and drops.

URCU version 0.2. Mathieu Desnoyers posted version 0.2 of the userspace RCU library he has been working on. It contains some clarifications for three function usages.

The latest kernel release was 2.6.32-rc1|rc2 (both the same).

Greg Kroah-Hartman posted a series of review patches for the 2.6.27.36 stable kernel, and 136 review patches for the 2.6.31.2 stable kernel.

Rafael J. Wysocki posted a summary of regressions since the 2.6.31 kernel, based upon bug filings on the kernel.org bugzilla. As he notes, there aren’t too many new regressions since 2.6.31, but there are still “quite a number” since 2.6.30 and it’s been that way for quite some time.

Stephen Rothwell posted a linux-next tree for October 1st. Since Wednesday, the linux-next fixes tree still has a fix for powerpc/kvm, there is still a reverted SCSI commit, the sound tree gained a build failure (so the previous day’s version of that tree was used), the block tree lost its conflicts but gained a failure for which a commit was reverted, and the drm tree lost its conflict. The total subtree count remained steady at 139 trees.

That’s a summary of today’s Linux Kernel Mailing List traffic, for further information visit www.kernel.org. I’m Jon Masters.