Diff for "LinuxChanges" - Linux Kernel Newbies

Differences between revisions 6 and 78 (spanning 72 versions)

Comprehensible changelog of the linux kernel, inspired by [http://wiki.dragonflybsd.org/index.php/DragonFly_Status Dragonfly's status]. Another good places to get more information about the linux kernel are [http://www.kernel-traffic.org Kernel traffic] and [http://www.lwn.net LWN] and their [http://lwn.net/Kernel/ "kernel status" articles], [http://lwn.net/Articles/driver-porting/ driver porting guide] and the [http://lwn.net/Articles/2.6-kernel-api/ API changes in 2.6] - many of the links here are linking to LWN articles and we wouldn't have been able to restore the 2.5.x-2.6.x changelog without them (you may be insterested in subscribing so Jonathan can keep up the good work ) Before adding things here look at the RULES section at the end of the page!! (send a mail if you think something is missing here and you don't want to/can't create an account)

2.6.14

STILL NOT RELEASED!!
Numa-aware slab allocator [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e498be7dafd72fd68848c1eef1575aa7c5d658df (commit - benchmarks)]
Lazy page table copies in fork(): Defer copying of ptes until fault time when it is possible to reconstruct the pte from backing store, speeding up fork() greatly specially for processes using lots of shared memory [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d992895ba2b27cf5adf1ba0ad6d27662adc54c5e (commit)]
Add /proc/$PID/smaps: Shows how much memory is resident in each mapping. Useful for people who want to perform memory consumption analysis [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e070ad49f31155d872d8e96cab2142840993e3c0 (commit)]
Four-level page table support for the ppc64 architecture: extends the usable user address range to 44 bits (16T). [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e28f7faf05159f1cfd564596f5e6178edba6bd49 (commit)]
PPTP (Point-to-Point Tunneling Protocol) support: [http://www.ietf.org/rfc/rfc2637.txt RFC 2637]. Used to implement VPN products (notably, Microsoft in all the Windows versions). [http://en.wikipedia.org/wiki/PPTP Wikipedia article] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=926b50f92a30090da2c1a8675de954c2d9b09732 (commit)]
[http://fuse.sourceforge.net/ FUSE]: Allows to implement a fully functional filesystem in a userspace program
[http://v9fs.sourceforge.net/ 9P support]: Linux port of the [http://www.cs.bell-labs.com/sys/doc/9.html Plan9]'s [http://plan9.bell-labs.com/sys/man/5/INDEX.html 9P protocol] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=93fa58cb831337fdf5d36b3b913441100a484dae (commit)]
DCCP: "Datagram Congestion Control Protocol". Datagram protocol (like UDP), but with a congestion control mechanism. [http://lwn.net/Articles/149756/ (LWN article)] Currently a [http://www.icir.org/kohler/dcp/draft-ietf-dccp-spec-11.txt RFC draft] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=7c657876b63cb1d8a2ec06f8fc6c37bb8412e66c (commit)]
[http://relayfs.sourceforge.net/ RelayFS]: Relayfs is just a bunch of per-cpu kernel buffers that can be efficiently written into from kernel code. These buffers are represented as files which can be mmap'ed and directly read from in user space. The purpose of this setup is to provide the simplest possible mechanism allowing potentially large amounts of data to be logged in the kernel and 'relayed' to user space." [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e82894f84dbba130ab46c97748c03647f8204f92 (commit)]
securityfs filesystem [http://lwn.net/Articles/153366/ (LWN article)] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b67dbf9d4c1987c370fd18fdc4cf9d8aaea604c2 (commit)]
SAS transport class [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c7ebbbce366c02e5657ac6b6059933fe0353b175 (commit)]
Remove ACPI S4 BIOS support [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b01d8684e9e5b04270970c97df856d47668267e3 (commit)]
Add netlink connector: userspace <-> kernel space easy to use communication module which implements easy to use bidirectional message bus using netlink as its backend [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=7672d0b54411371e0b6a831c1cb2f0ce615de6dc (commit)], also a "async connector mode" [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=acd042bb2de50d4e6fb969281a00cc8b8b71e46d (commit)]
Suspend support for CIFS filesystem [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ede1327ea4ca8019ec6df24b3e837def091c26b8 (commit)]
[http://ipw2100.sourceforge.net/ ipw2100] and [http://ipw2200.sourceforge.net/ ipw2200] wireless drivers (intel centrino) [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=2c86c275015c880e810830304a3a4ab94803b38b (commit)] - [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=43f66a6ce8da299344cf1bc2ac2311889cc88555 (commit)]
[http://hostap.epitest.fi/ HostAP]: Adds support to work as "Wireless Access Point" [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ff1d2767d5a43c85f944e86a45284b721f66196c (commit)]
[http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Linux.Wireless.Extensions.html Wireless extensions] API update to version 19 [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6582c164f2b3b6e58d1f13c1c031b19ee691eb14 (commit)]
ISA DMA suspend for x86/x86-64 [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=795312e763569ce4df67e7a0ca726a9901358fa2 (commit)] - [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=7dc24db1757f950f8bd21b7191106d4bf5134be7 (commit)]
Keys: Add possessor permissions to keys. It adds extra permission grants to keys for the possessor of a key in addition to the owner, group and other permissions bits. This makes SUID binaries easier to support without going as far as labelling keys and key targets using the LSM facilities [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=664cceb0093b755739e56572b836a99104ee8a75 (commit)]

2.6.13

Released August 29, 2005 [http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.13 changelog]
Execute-in-place support: Traditionally, programs are loaded from disk to memory to be executed. However, the current wave of embedded devices store programs in a ROM/flash chip. XIP allows the kernel executing programs directly from that ROM, without being copied to RAM (saving RAM space), and bypassing the page cache/io scheduler layers (since they're not needed). [http://lwn.net/Articles/135472/ (LWN article)]
x86 now uses the generic PCI bus setup code for assigning unassigned resources
Voluntary preemption patches
build-time configurable clock interrupt frequency: Now HZ defaults to 256 in x86. 1000 is better for "interactivity" (desktops) and 100 is good for performance (servers) and saves some energy in laptops. [http://lwn.net/Articles/145973/ (LWN article)]
inotify [http://lwn.net/Articles/104343/ (LWN article)] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0eeca28300df110bd6ed54b31193c83b87921443 (commit)]
Support for the Xtensa architecture: [http://www.tensilica.com/products/xtensa_architecture.htm 32-bit architecture] used in embedded devices
Improved CFQ IO scheduler: With support for I/O priorities [http://lwn.net/Articles/143474/ (LWN article)]
kexec and kdump: Kexec allows users to load a new kernel from another running kernel. By preserving the memory contents in a crash scenario, kexec allows to implement kdump. Kdump is able to get a memory dump of the previous kernel, and be used as a debugging tool. [http://lwn.net/Articles/108595/ (LWN article)]
Runtime selectable TCP congestion algorithm: Allow using setsockopt to set TCP congestion control to use on a per socket basis. [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=5f8ef48d240963093451bcf83df89f1a1364f51d (commit)] - [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=317a76f9a44b437d6301718f4e5d08bd93f98da7 (commit)]
Add several TCP congestion modules: H-TCP [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a7868ea68d29eb2c037952aeb3b549cf05749a18 commit], TCP Hybla [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=835b3f0c0d7e1f716c45ec576662eac7a68b8548 (commit)], High Speed TCP (HS-TCP) [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a628d29b56d3f420bf3ff1d7543a9caf3ce3b994 (commit)], TCP Westwood [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=8727076289ec55298a05cabddf02b374d13c1624 (commit)], TCP BIC [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=83803034f4233d810c4adc52008921da060c55d1 (commit)]
Removal of the devfs configuration option

2.6.12

Released June 17, 2005 [http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.12 changelog]
Pageout throttling: With silly pageout testcases it is possible to place huge amounts of memory under I/O. With a large request queue (CFQ uses 8192 requests) it is

possible to place _all_ memory under I/O at the same time. This means that all memory is pinned and unreclaimable and the VM gets upset and goes oom. This patch limits the amount of memory which is under pageout writeout to be a little more than the amount of memory at which balance_dirty_pages() callers will synchronously throttle. This means that heavy pageout activity can starve heavy writeback activity completely, but heavy writeback activity will not cause starvation of pageout [http://kernel.org/git/?p=linux/kernel/git/torvalds/old-2.6-bkcvs.git;a=commit

-  ⇤ ← Revision 6 as of 2005-09-21 19:25:25 → 
  Size: 1892
  Editor: diegocalleja
  Comment:
+   ← Revision 78 as of 2005-10-11 12:34:05 → ⇥
  Size: 10180
  Editor: diegocalleja
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 1:
-The purpose of this page is tracking and explaining the features added in every release, just like the [http://wiki.dragonflybsd.org/index.php/DragonFly_Status Dragonfly people did].
+Comprehensible changelog of the linux kernel, inspired by  [http://wiki.dragonflybsd.org/index.php/DragonFly_Status Dragonfly's status]. Another good places to get more information about the linux kernel are [http://www.kernel-traffic.org Kernel traffic] and [http://www.lwn.net LWN] and their [http://lwn.net/Kernel/ "kernel status" articles], [http://lwn.net/Articles/driver-porting/ driver porting guide] and the [http://lwn.net/Articles/2.6-kernel-api/ API changes in 2.6] - many of the links here are linking to LWN articles and we wouldn't have been able to restore the 2.5.x-2.6.x changelog without them (you may be insterested in subscribing so Jonathan can keep up the good work ;) ) Before adding things here look at the RULES section at the end of the page!! (send a mail if you think something is missing here and you don't want to/can't create an account)
 Line 3:
-It'd be nice if kernel hackers would spend some minutes adding their stuff here. The one place where you can find a comparable changelog are the fabulous LWN kernel articles: http://lwn.net/Kernel/, or the [http://lwn.net/Articles/driver-porting/ driver porting guide] - but there's no reason why the kernel community shouldn't embrace and extend those efforts ;)

TODO:
 * Import (and extend, explain, etc) LWN's [http://lwn.net/Articles/2.6-kernel-api/ list of 2.6 API changes] (need to ask for permission?)
 * Import [http://kernelnewbies.org/status/latest.html Kernelnewbies status] list
 * Import relevant data from [http://www.codemonkey.org.uk/post-halloween-2.5.txt davej's post halloween document]
 * Keep track of what gets changed
+===== 2.6.14 =====
  * '''STILL NOT RELEASED!!'''
  * Numa-aware slab allocator [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e498be7dafd72fd68848c1eef1575aa7c5d658df (commit - benchmarks)]
  * Lazy page table copies in fork(): Defer copying of ptes until fault time when it is possible to reconstruct the pte from backing store, speeding up fork() greatly specially for processes using lots of shared memory [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d992895ba2b27cf5adf1ba0ad6d27662adc54c5e (commit)]
  * Add /proc/$PID/smaps: Shows how much memory is resident in each mapping.  Useful for people who want to perform memory consumption analysis [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e070ad49f31155d872d8e96cab2142840993e3c0 (commit)]
  * Four-level page table support for the ppc64 architecture: extends the usable user address range to 44 bits (16T). [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e28f7faf05159f1cfd564596f5e6178edba6bd49 (commit)]
  * PPTP (Point-to-Point Tunneling Protocol) support: [http://www.ietf.org/rfc/rfc2637.txt RFC 2637]. Used to implement VPN products (notably, Microsoft in all the Windows versions). [http://en.wikipedia.org/wiki/PPTP Wikipedia article] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=926b50f92a30090da2c1a8675de954c2d9b09732 (commit)]
  * [http://fuse.sourceforge.net/ FUSE]: Allows to implement a fully functional filesystem in a userspace program
  * [http://v9fs.sourceforge.net/ 9P support]: Linux port of the [http://www.cs.bell-labs.com/sys/doc/9.html Plan9]'s [http://plan9.bell-labs.com/sys/man/5/INDEX.html 9P protocol] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=93fa58cb831337fdf5d36b3b913441100a484dae (commit)]
  * DCCP: "Datagram Congestion Control Protocol". Datagram protocol (like UDP), but with a congestion control mechanism. [http://lwn.net/Articles/149756/ (LWN article)] Currently a [http://www.icir.org/kohler/dcp/draft-ietf-dccp-spec-11.txt RFC draft] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=7c657876b63cb1d8a2ec06f8fc6c37bb8412e66c (commit)]
  * [http://relayfs.sourceforge.net/ RelayFS]: Relayfs is just a bunch of per-cpu kernel buffers that can be efficiently written into from kernel code. These buffers are represented as files which can be mmap'ed and directly read from in user space. The purpose of this setup is to provide the simplest possible mechanism allowing potentially large amounts of data to be logged in the kernel and 'relayed' to user space." [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e82894f84dbba130ab46c97748c03647f8204f92 (commit)]
  * securityfs filesystem [http://lwn.net/Articles/153366/ (LWN article)] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b67dbf9d4c1987c370fd18fdc4cf9d8aaea604c2 (commit)] 
  * SAS transport class [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c7ebbbce366c02e5657ac6b6059933fe0353b175 (commit)]
  * Remove ACPI S4 BIOS support [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b01d8684e9e5b04270970c97df856d47668267e3 (commit)]
  * Add netlink connector:  userspace <-> kernel space easy to use communication module which implements easy to use bidirectional message bus using netlink as its backend [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=7672d0b54411371e0b6a831c1cb2f0ce615de6dc (commit)], also a "async connector mode" [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=acd042bb2de50d4e6fb969281a00cc8b8b71e46d (commit)]
  * Suspend support for CIFS filesystem [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ede1327ea4ca8019ec6df24b3e837def091c26b8 (commit)]
  * [http://ipw2100.sourceforge.net/ ipw2100] and [http://ipw2200.sourceforge.net/ ipw2200] wireless drivers (intel centrino) [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=2c86c275015c880e810830304a3a4ab94803b38b (commit)] - [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=43f66a6ce8da299344cf1bc2ac2311889cc88555 (commit)]
  * [http://hostap.epitest.fi/ HostAP]: Adds support to work as "Wireless Access Point" [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ff1d2767d5a43c85f944e86a45284b721f66196c (commit)]
  * [http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Linux.Wireless.Extensions.html Wireless extensions] API update to version 19 [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6582c164f2b3b6e58d1f13c1c031b19ee691eb14 (commit)]
  * ISA DMA suspend for x86/x86-64 [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=795312e763569ce4df67e7a0ca726a9901358fa2 (commit)] - [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=7dc24db1757f950f8bd21b7191106d4bf5134be7 (commit)]
  * Keys: Add possessor permissions to keys. It adds extra permission grants to keys for the possessor of a key in addition to the owner, group and other permissions bits. This makes SUID binaries easier to support without going as far as labelling keys and key targets using the LSM facilities [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=664cceb0093b755739e56572b836a99104ee8a75 (commit)]
-Line 12:
+Line 26:
+===== 2.6.13 =====
  * Released August 29, 2005 [http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.13 changelog]
  * Execute-in-place support: Traditionally, programs are loaded from disk to memory to be executed. However, the current wave of embedded devices store programs in a ROM/flash chip. XIP allows the kernel executing programs directly from that ROM, without being copied to RAM (saving RAM space), and bypassing the page cache/io scheduler layers (since they're not needed). [http://lwn.net/Articles/135472/ (LWN article)]
  * x86 now uses the generic PCI bus setup code for assigning unassigned resources
  * Voluntary preemption patches
  * build-time configurable clock interrupt frequency: Now HZ defaults to 256 in x86. 1000 is better for "interactivity" (desktops) and 100 is good for performance (servers) and saves some energy in laptops. [http://lwn.net/Articles/145973/ (LWN article)]
  * inotify [http://lwn.net/Articles/104343/ (LWN article)] [http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0eeca28300df110bd6ed54b31193c83b87921443 (commit)]
  * Support for the Xtensa architecture: [http://www.tensilica.com/products/xtensa_architecture.htm 32-bit architecture] used in embedded devices
  * Improved CFQ IO scheduler: With support for I/O priorities [http://lwn.net/Articles/143474/ (LWN article)]
  * kexec and kdump: Kexec allows users to load a new kernel from another running kernel. By preserving the memory contents in a crash scenario, kexec allows to implement kdump. Kdump is able to get a memory dump of the previous kernel, and be used as a debugging tool. [http://lwn.net/Articles/108595/ (LWN article)]
  * Runtime selectable TCP congestion algorithm: Allow using setsockopt to set TCP congestion control to use on a per socket basis. [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=5f8ef48d240963093451bcf83df89f1a1364f51d (commit)] - [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=317a76f9a44b437d6301718f4e5d08bd93f98da7 (commit)]
  * Add several TCP congestion modules: H-TCP [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a7868ea68d29eb2c037952aeb3b549cf05749a18 commit], TCP Hybla [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=835b3f0c0d7e1f716c45ec576662eac7a68b8548 (commit)], High Speed TCP (HS-TCP) [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a628d29b56d3f420bf3ff1d7543a9caf3ce3b994 (commit)], TCP Westwood [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=8727076289ec55298a05cabddf02b374d13c1624 (commit)], TCP BIC [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=83803034f4233d810c4adc52008921da060c55d1 (commit)]
  * Removal of the devfs configuration option
-Line 13:
+Line 40:
-.6.14:
2.6.13:
2.6.12:
2.6.11:
2.6.10:
2.6.9:
2.6.8:
2.6.7:
2.6.6:
2.6.5:
2.6.4:
2.6.3:
2.6.2:
2.6.1:
2.6.0:
2.6.0-test9:
  * [http://lwn.net/Articles/44243/ libata driver architecture]	(Jeff Garzik)
2.6.0-test6:
  * [http://marc.theaimsgroup.com/?l=linux-kernel&m=104344596912094&w=2 32-bit dev_t] (Andries Brouwer, Al Viro)
2.6.0-test3:
  * [http://www.nsa.gov/selinux/index.html SELinux] (Stephen Smalley, SELinux team)
2.6.0-test1:
  * [http://www.linuxvirtualserver.org/ Linux Virtual Server layer] (Wensong Zhang)
2.5.75:
  * [http://marc.theaimsgroup.com/?l=linux-mm&m=104529418208788&w=2 Anticipatory Scheduler] (Nick Piggin, Andrew Morton)
2.5.71:
  * [http://marc.theaimsgroup.com/?l=linux-kernel&m=104981044405395&w=2 Switch the IDE I/O layers to taskfile](Bartlomiej Zolnierkiewicz, Alan Cox)
2.5.70:
  * [http://www.linux-usb.org/gadget USB gadget support] (David Brownell, Stuart Lynne, Greg Kroah-Hartman)
+===== 2.6.12 =====
  * Released June 17, 2005 [http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.12 changelog]
  * Pageout throttling: With silly pageout testcases it is possible to place huge amounts of memory under I/O.  With a large request queue (CFQ uses 8192 requests) it is
possible to place _all_ memory under I/O at the same time. This means that all memory is pinned and unreclaimable and the VM gets upset and goes oom. This patch limits the amount of memory which is under pageout writeout to be a little more than the amount of memory at which balance_dirty_pages() callers will synchronously throttle. This means that heavy pageout activity can starve heavy writeback activity completely, but heavy writeback activity will not cause starvation of pageout [http://kernel.org/git/?p=linux/kernel/git/torvalds/old-2.6-bkcvs.git;a=commit