For Tuesday, June 9th 2009, I'm Jon Masters with a summary of today's LKML traff
ic.

In today's issue: Linux 2.6.30, performance overhead, IO scheduler based IO
controller, VIA Centaur CPUs, and procfs documentation.

Linux 2.6.30. Linus Torvalds finally announced the release of 2.6.30. Quoting
Linus, "I'm sure we've missed something, and I know we have some regressions
pending. At the same time, we do need the coverage of a [real] release, and
on the whole it looks pretty good. We've fixed a few regressions in the
last few days, and there's always 2.6.30.x". Linus refers to
the kernelnewbies.org site writeup for further details.

Performance overhead. Continuing the previous discussion concerning the
overhead of enabling certain kernel configuration options, Ingo Molnar pointed
out that due to the way memory zones are allocated, we begin satisfying
requests from the highmem zone first, which increases the need for kmap()
mappings (on those x86-32 systems where this is applicable) if this memory
happens to be used heavily in-kernel, for example for filesystem cacheing
purposes, although - as Linus pointed out - it is intended this way in order
to benefit the average case of userspace tasks, for which we obviously do
not require a kmap/kunmap as the memory is directly mapped. The
dicussion lead on to whether there is still a need for highmem kernels and
kernel PAE support. The conclusion was that there is for the moment, since
many 32-64 bit migrations have been offset by newer embedded users - though it
was pointed out that many of these folks don't share bug reports on breakage.

IO Scheduler based IO controller. Vivek Goyal posted version 4 of his IO
scheduler based IO controller patchset. This patchset aims to provide IO
bandwidth control at the IO scheduler level, but does not directly address
higher level (layered) logical devices - as before, Vivek includes some ideas
about handling this, along with a link to a LWN article on the topic.

Converting block trace points to TRACE_EVENT. Li Zefan posted version 3 of a
patchset intended to convert the block trace points over to TRACE_EVENT. As Li
points out, doing so enables zero-copy and per-cpu splice() tracing,
structured logging records exposed under debugfs, and arbitrary per-tracepoint
filer expressions to be defined by the user. Li's benchmarks show that the
performance hit of tracing is reduced marginally by using the new patches
(especially because of the use of splice()), although it was already
pretty small to begin with.

VIA Centaur CPUs. Harald Welte (who listeners may recall became the VIA Free
and Open Source Software Liaison) posted a number of fixes for VIA/Centaur
CPUs. He also responded to a discussion concerning setting the correct CPU
frequency automatically in e_powersaver in which Michael Zick claimed that
the cpuid instruction provides information about the Guaranteed Stable
Frequency (GSF) expressing uncertainty that the CPUID provided
anything more than the maximum clock frequency in ASCII.

Procfs documentation. Stefani Seibold posted a documentation update for
procfs, covering the changes that have been made across recent releases. The
update includes documentation of new /proc/self/status flags, as well as
changes to the memory maps, including the newer smaps extension. The latter
allows one to view the memory consumption for each of a process' mappings.

In today's announcements: Linux 2.6.30 was released on Tuesday. Christoph
Hellwig posted an "XFS status update for May 2009", in which he noted a new
release of xfsprogs and ongoing work on xfstests to allow those tests to be
run on any filesystem, and not just XFS ones.

The latest kernel release is 2.6.30, which was released by Linus on Tuesday,
at 8:36pm Pacific Daylight Time.

The next merge window won't really be open for a "day or two" because Linus is
keen to see people actually test the 2.6.30 release first.

Andrew Morton posted an mm-of-the-moment snapshot for 2009-06-09-17-52.

The 2.6.29 -stable kernel. Greg K-H posted an 87-part patch review series in
which he requested responses for 2.6.29.5-rc1 prior to June 11 at 09:00:00
UTC, which is likely to be after you hear this.

Stephen Rothwell posted a linux-next tree for May 9th. Since the previous
compose last Thursday, two new trees were added ("irda" and "voyager"), one of
which ("voyager") was immediately dropped due to a build problem. The tree
still fails to build in a powerpc allyesconfig build configuration, and
contains a large number of other conflicts. The total subtree count has
increased to 144, given the addition of the two aforementioned items.

That's a summary of today's LKML traffic. For further information visit kernel.org. I'm Jon Masters.