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@@ -170,27 +170,6 @@
-
-
Lustre filesystem [3.12]
-
- -
- A distributed filesystem, popular for cluster computing
- applications
-
- -
- Developed out-of-tree since 1999, but now added to Linux staging
- directory
-
- -
- Was included in squeeze but dropped from wheezy as it didn't
- support Linux 3.2
-
- -
- Userland is now missing from Debian
-
-
-
-
Network busy-polling [3.11] (1)
A conventional network request/response process looks like:
@@ -253,6 +232,27 @@
+
+
Lustre filesystem [3.12]
+
+ -
+ A distributed filesystem, popular for cluster computing
+ applications
+
+ -
+ Developed out-of-tree since 1999, but now added to Linux staging
+ directory
+
+ -
+ Was included in squeeze but dropped from wheezy as it didn't
+ support Linux 3.2
+
+ -
+ Userland is now missing from Debian
+
+
+
+
Btrfs offline dedupe [3.12]
@@ -284,12 +284,11 @@
and ebtables
-
- All require a specific kernel module for each type of match
- and each possible action
+ All limited to single protocol, and need a kernel module for
+ each match type and each action
-
- Userland could only use the four protocol-specific APIs,
- although the internal netfilter API is more flexible
+ Kernel's internal netfilter API is more flexible
-
nftables exposes more of this flexibility, allowing userland
@@ -299,12 +298,87 @@
nftables userland tool uses this API and is already packaged
-
- Eventually, the old APIs will be removed and the old userland
+ Eventually, old APIs will be removed and old userland
tools must be ported to use nftables
+
+
User-space lockdep [3.14]
+
+ -
+ Kernel threads and interrupts all run in same address space,
+ using several different synchronisation mechanisms
+
+ -
+ Easy to introduce bugs that can result in deadlock, but hard to
+ reproduce them
+
+ -
+ Kernel's 'lockdep' system dynamically tracks locking operations
+ and detects potential deadlocks
+
+ -
+ Now available as a userland library! Except we need to package
+ it (build from linux-tools source package)
+
+
+
+
+
+
arm64 and ppc64el ports
+
+ -
+ 'arm64' architecture was added in Linux 3.7, but was not yet
+ usable, and no real hardware was available at the time
+
+ -
+ Upstream Linux arm64 kernel, and Debian packages, should now run
+ on emulators and real hardware
+
+ -
+ 'powerpc' architecture has been available for many years,
+ but didn't support kernel running little-endian
+
+ -
+ Linux 3.13 added little-endian kernel suport, along with new
+ userland ELF ABI variant - we call it ppc64el
+
+ -
+ Both ports now being bootstrapped in unstable and are candidates
+ for jessie release
+
+
+
+
+
+
File-private locking [3.15]
+
+ -
+ POSIX says that closing a file descriptor removes
+ the process's locks on that file
+
+ -
+ What if process has multiple file descriptors for the same
+ file? It loses all locks obtained through any descriptor!
+
+ -
+ Multithreaded processes may require serialisation around
+ file open/close to ensure they open each file exactly once
+
+ -
+ Hard and symbolic links can hide that two files are really the
+ same
+
+ -
+ Linux now provides file-private locks, associated with a
+ specific open file and removed when last descriptor for the
+ open file is closed
+
+
+
+
Questions?