Linux 3.7 released

by moonboots • 14 years ago

254 112 14 years ago

autotravis• 14 years ago

>'"Fast Open" is a optimization to the process of stablishing a TCP connection that allows the elimination of one round time trip from certain kinds of TCP conversations. Fast Open could result in speed improvements of between 4% and 41% in the page load times on popular web sites.'

Interesting... anyone know more about this?

kzrdude• 14 years ago

Recommended LWN article: TCP Fast Open: expediting web services http://lwn.net/Articles/508865/

gghh• 14 years ago

thank you, interesting link. Does TCP Fast Open have anything to do with the "slow start", which a few major websites are known to violate[1][2] ? just out of curiosity. It doesn't look so, at a first glance.

[1] http://en.wikipedia.org/wiki/Slow-start [2] http://blog.benstrong.com/2010/11/google-and-microsoft-cheat...

ck23• 14 years ago

http://en.wikipedia.org/wiki/TCP_Fast_Open

I guess CentOS will get this in 2020, sigh, still waiting for initrwnd 10 support.

Nux• 14 years ago

If all you need is the kernel, then you can use the one provided by the elrepo.org project.

sp3322• 14 years ago

Wouldn't this conflict with TCP cookies, which were (partially) added to the kernel just a little while ago?

B-Con• 14 years ago

More detailed explanation here: http://lwn.net/Articles/508865/

sliverstorm5• 14 years ago

Ah, the downsides to stability.

The particularly unfortunate part is, as much of the world's commercial hosting runs on RHEL, it's the world that doesn't get this until 2020. Well, except for services that roll custom kernels.

mediocregopher2• 14 years ago

CentOS 6 actually does support the initrwnd 10 modification. I forget what exactly is involved but we have it working on our servers where I work.

jlgreco• 14 years ago

Have you considered using Scientific Linux? It seems to do a much better job of tracking RHEL in a timely manner.

allerratio2• 14 years ago

RHEL 7 is planned for 2013. If it's released in late 2013 it could get in

JoshTriplett• 14 years ago

LWN had a detailed article about it: https://lwn.net/Articles/508865/

mixmastamyk• 14 years ago

How long until this comes to Windows and OSX clients? Until then it doesn't seem that this will get much use. Didn't find anything on a preliminary google search.

aartur• 14 years ago

Optimization of file deletion in ext4 gives nice results (from a commit message):

> X86 before (linux 3.6-rc4):

> # time rm -f test1

> real 0m2.710s

> user 0m0.000s

> sys 0m1.530s

> X86 after:

> # time rm -f test1

> real 0m0.644s

> user 0m0.003s

> sys 0m0.060s

The commit affects 5 lines only.

EDIT. Not sure if this optimization applies to filesystems mounted with standard journaling options...

unwind• 14 years ago

Sounds nice, good find!

I dug up the commit: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git... which seems to be a bit older than I would have expected. Of course, this being Linux, "old" means it's from September 19th.

caf2• 14 years ago

The merge window for 3.7 opened on September 30th, so it's not that old.

devastor• 14 years ago

What journaling options did you use?

georgemcbay• 14 years ago

Pro: Eliminates the sinking feeling I get when an rm with wildcards is "taking too long".

Con: All my files are gone before I can frantically ctrl-c to save some of them.

jug6ernaut• 14 years ago

ARM x64, wow. Is this really necessary? Or just a prelude to some new applications?

When i think of ARM i think of Mobile Phones, total ram isn't an issue(yet?) Are there other advantages?

stonemetal• 14 years ago

AMD has announced that they are going to start shipping 64bit ARM systems in the near future(a year or two out).

http://www.anandtech.com/show/6418/amd-will-build-64bit-arm-...

binarycrusader3• 14 years ago

Better performance, and yes, it won't be long now before mobile devices ship with more than 4GB of memory.

Don't forget AMD's announcement about ARM64 based servers.

mbell5• 14 years ago

ARM64 isn't required for > 4GB physical memory. The cortex-a15 can already address up to 1TB and is already shipping. Only the per process limit is locked to 4GB on a 32 bit core.

bad_user• 14 years ago

ARM processors are used for servers too.

robertelder• 14 years ago

http://xkcd.com/619/

krakensden• 14 years ago

AMD is looking into shipping ARM server chips and boards, IIRC.

jevinskie• 14 years ago

64-bit address space lets virtual memory related things like ASLR really shine, even if the physical RAM is < 4GB.

stusmall2• 14 years ago

The more interesting part is the ARM multi-platform support. 64 bit ARM cores haven't hit the market yet, but the ability to run one ARM kernel on several different hardware set ups is useful today.

cjbprime• 14 years ago

> When i think of ARM i think of Mobile Phones, total ram isn't an issue(yet?) Are there other advantages?

We don't think about it much, but the total power draw of a data center is a huge cost, and ARM servers are lower-power than x86 servers. Every step towards being able to replace x86 servers with ARM ones is saving the people who pay data center power bills lots of money.

ChuckMcM• 14 years ago

It will certainly make testing early access silicon from AMD more interesting. But that nice benefit aside, having a large virtual address space is really handy for a lot of things.

rythie• 14 years ago

4GB is the limit with 32bit. It's starting to be used on servers, so that's an issue there. But even on phones:

   Moterola Droid 256MB [2009]
   Google Nexus One 512MB [2010]
   Galaxy Nexus 1GB [2011]
   Google Nexus 4 2GB [2012]

It doesn't look like it will be long before we need 4GB or more. I would expect, like with x86, you need 64bit even to access the full 4GB (due to memory mapped devices)

jerf• 14 years ago

In addition to everybody else's replies, remember, cell phones are computers. Chant it to yourself: Cell phones are computers. Cell phones are computers. There is nothing that a notebook will need that a cell phone won't need just a year or three later. Cell phones can chew through any amount of power you give them, with augmented reality, being used as laptops with optional shells, the sky is the limit. Do not limit your mental model of cell phones to "glorified phone", the end game is "computer with cell network interface."

jws• 14 years ago

Remember that memristors are going to reinvent computer memory by 2014? (speed and power near dynamic RAM, but nonvolatile) When the storage hierarchy gets retuned you may find all of your device's nonvolatile storage in your address space. Or maybe not. http://en.wikipedia.org/wiki/Resistive_random-access_memory

Beyond that…

The ARM 64 bit comes with 31 64 bit registers instead of 14 32 bit registers.

There are a number of instruction set differences, such that you run the same object code on previous architectures.

The NEON unit also gets twice the registers, double precision floating point, and IEEE 754 compliance.

Hoff• 14 years ago

HP has announced plans for power-efficient ARM-based servers with their "Project Moonshot" program, and starting with their "Project Redstone" Calxeda ARM server development platform:

http://www.theregister.co.uk/2011/11/01/hp_redstone_calxeda_...

http://www.hp.com/hpinfo/globalcitizenship/environment/techg...

http://h20195.www2.hp.com/V2/GetPDF.aspx/4AA3-9839ENW.pdf

mikeash• 14 years ago

Bitness is more about per-process address space than total RAM. For example, a 32-bit process could not memory map a file over (somewhat less than) 4GB in size, while a 64-bit process doesn't have this problem. Wanting to memory map large files is something you could do on just about any current mobile phone.

Also think Moore's Law. Current phones are sporting 1GB of RAM. It will just be a few years before they exceed 4GB, and it's easier to get the software support ready now.

mtgx• 14 years ago

No it won't be. Some of the high-end phones already have 2 GB, and next year it seems they'll have 3 GB of RAM. So 64 bit is arriving just on time in 2014 (although Cortex A15 supports extension to 40 bit, but using that may be a bit messy):

http://www.phonearena.com/news/Sonys-2013-flagships-tipped-Q...

protomyth• 14 years ago

per the article: "The new 64 bit CPUs can run 32 bits code, but the 64 bit instruction set is completely new, not just 64 bit extensions to the 32 bit instruction set, so the Linux support has been implemented as a completely new architecture."

sdafdasdfasdf• 14 years ago

from "TCP Fast Open: expediting web services": http://lwn.net/Articles/508865/

> Furthermore, the server should periodically change the encryption key used to generate the TFO cookies, so as to prevent attackers harvesting many cookies over time to use in a coordinated attack against the server.

What is going to do this? I hope this is built-in somehow.

marshray5• 14 years ago

It looks like the key will be accessible via the proc filesystem. But it's anyone's guess how many distros will faithfully schedule a cron job to rotate the key.

EDIT: Looks like the key is chosen at kernel module "late init" time. I think this is before any init scripts have had the opportunity to add back any entropy persisted from previous boots. So the entropy in the kernel pool is minimal. It may be plausible for a remote attacker to guess the key for a bunch of servers.

Also, if the key is not rotated by cron, it provides a single-packet method for a remote attacker to observe that a server has been rebooted since he last checked. This will give a good indication of how often security patches have been applied.

http://git.kernel.org/linus/1046716368979dee857a2b8a91c4a883... http://git.kernel.org/linus/168a8f58059a22feb9e9a2dcc1b8053d... http://git.kernel.org/linus/8336886f786fdacbc19b719c1f7ea91e...

aleyan• 14 years ago

Might be better to have the keys rotated after a certain number of TFO cookies are generated rather than on a time-based schedule. This will prevent attackers from trying to make a huge number of requests in a set period of time.

elux• 14 years ago

Kernel newbies is down: http://www.isup.me/http://kernelnewbies.org/Linux_3.7

Cached version: http://webcache.googleusercontent.com/search?q=cache:vjkg-vG...

jey• 14 years ago

  perf trace will show the events associated with the
  target, initially syscalls, but other system events like 
  pagefaults, task lifetime events, scheduling events, etc.

I'm excited.

tocomment2• 14 years ago

Can you explain this a bit more? It sounds interesting.

VMG• 14 years ago

This allows developers to see what their programs are doing in more detail. They can then use that information to optimize their code.

majke• 14 years ago

Linux is suffering from a lack of a good debugging API. There is a decent progress in the kernel debugging and profiling tools, but for userspace no changes were made for a long time.

"ptrace" is the main userspace debugging API, used behind tools like "strace" or "gdb", but it's old and clumsy. Quite new "perf" tool, on the other hand, allows user to get various CPU/Kernel stats mostly useful for profiling. Before "perf" you could only try to emulate your program using "valgrind" to get, say cache misses.

The command "perf trace", seems to move "perf" more into the "ptrace" domain. This is indeed exciting.

azth• 14 years ago

Is it different from this: https://perf.wiki.kernel.org/index.php/Tutorial ?

contingencies• 14 years ago

Based on a session I saw at the Linux Collaboration Summit 2011 in San Francisco there are actually a few competing profiling toolkits. While most of these are aimed at kernel developers there is also the potential to use these more generally either (1) for optimization, or (2) in conjunction with various security toolkits to automate the systematic reduction of kernel-level attack space.

While both are a can of worms, (1) is more so. With regards to (2), AFAIK it is generally accepted that grsec provides the easiest profiling tools here; whilst 'roll your own' is never as secure as something locked down by multiple third parties 'in the know' and to a finite extent (see: NSA SELinux), it is far better than nothing, and very frequently custom code or the latest or patched version of a certain daemon will not have publicly accredited rulesets. Therefore grsec's solution is a reasonable basis for beginning here. Docs @ http://en.wikibooks.org/wiki/Grsecurity/The_Administration_U...

rgbrgb• 14 years ago

How long does this stuff usually take to get into a more comercial release? When will we see it in Ubuntu? Android?

chrisguitarguy• 14 years ago

http://en.wikipedia.org/wiki/List_of_Ubuntu_releases#Table_o...

Ubuntu 12.04 uses version 3.2, 12.10 is on kernel 3.5.

vladev• 14 years ago

Arch Linux will probably get it in a couple of weeks.

Android, on the other hand, will take much longer. It's sad as there are so many goodies in this for ARM, especially the multi-platform support. This will make updating Android version a lot easier (for manufacturers, hackers). Right now the one of the bigger issues is updating the kernels (and the closed drivers, to be honest).

thevdude2• 14 years ago

:( I just upgraded my arch a few days ago to 3.6.9, and now I'll have to do it again.

Tuna-Fish• 14 years ago

Ubuntu upgrades Kernel major versions to the latest available at the kernel freeze at every release. So, the features in 3.7 will hit Ubuntu systems with 13.04.

shardling• 14 years ago

If you're rooted, you can often find custom, more up to date Android kernels optimized for various phones. (The android dev community being what it is, sometimes they're not optimized very well, but if you hunt around and find a good one, they can make a difference to battery life/etc.)

jeltz• 14 years ago

In Debian stable it will probably arrive in about two years in the next Debian (8.0, jessie).

rbanffy• 14 years ago

IIRC a ton of stuff that was different between Android and mainline were to be merged in 3.7.

I suppose the next Android version will use this kernel.

zanny• 14 years ago

Ubuntu already has a generic 3.7 kernel (http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.7-raring/) in the kernel PPA. I'm already running it. Upbuntu usually has a shell script day of to download new releases. New Ubuntu versions are shipped with the latest kernel around the time of commmit freeze and just updates that line to avoid regressions in future kernel releases from harming systems inadvertently.

polarrat• 14 years ago

Sorry for being such a noob. But could someone please tell me the difference between "linux" and other linux builds like Ubuntu, RedHat etc?

qnk• 14 years ago

Linux is just the kernel and all different distributions (Ubuntu et al) are based on it.

Think of it as if the Twitter Api was the kernel and all different clients like Twiterrific or Tweebot were the distributions (Ubuntu, Fedora, etc...). Distributions are implementations of the kernel with lots of extra features and improvements.

rkalla• 14 years ago

If you've never been in the Linux world, can certainly see how this is confusing.

This announcement is for the Linux kernel. The different Linux distributions (Ubuntu, Redhat, etc.) all bundle different versions of the Linux kernel and umpteen number of packages around that to create a cohesive Desktop or Server experience.

The kernel is the one core, similar piece between ALL of the distros. It is the desktops, package managers, etc. that differs between the distros.

Nitramp• 14 years ago

Linux is an operating system kernel, the most basic layer of software managing the system and talking to your hardware. Linux exposes a standardized interface to the so called 'user space', where programs like Chrome or Apache etc run.

The Linux kernel is important, but only a small part of a whole operating system - it's the lowest layer, but there are lots of layers on top of it, including all the programs that the average user uses.

Ubuntu, Red Hat, and other Linux _distributions_ bundle a Linux kernel, common software packages, and utilities to manage these together. So there are many Linux distributions, but only one Linux kernel.

LeonidasXIV• 14 years ago

Linux is the kernel and Ubuntu, Red Hat are distributions that ship said kernel, together with a couple thousand other software packages.

SkyMarshal• 14 years ago

'Linux' = the operating system kernel

Ubuntu/Fedora/Arch/etc = Linux + lots of other stuff, without which the kernel is pretty useless (command shell/interpreter, GUI, command line tools, etc.)

Some more explanations that may help:

http://stackoverflow.com/questions/2013937/what-is-an-os-ker...

http://en.wikipedia.org/wiki/Kernel_(computing)

darkstalker• 14 years ago

I think this is important: "JFS: TRIM support". This just added another choice of filesystem for SSD drives.

jcastro• 14 years ago

Has anyone used this or a prerelease with the btrfs fsync improvements? I'm interested to see if dpkg performance is usable now.

Linux 3.7 released

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