7 ms·

The 3.9 kernel is out

99 points by edwintorok 14y ago

girvo 14y ago
I'm quite interested in the user namespaces feature, but can't come up with any use cases for myself other than say sandboxing (sort of) applications. Can anyone explain it a bit better? The lwn article is a bit heavy going
- FooBarWidget 14y ago
  It was primarily designed for sandboxing, so it's not strange that you cannot come up with other use cases.
  - girvo 14y ago
    That... Would make sense then. Now I feel stupid ;)
- gioele 14y ago
  What about this other LWN article "A new approach to user namespaces": https://lwn.net/Articles/491310/ https://lwn.net/Articles/491310/ ? > It allows for applications with no capabilities to use multiple uids and to implement privilege separation. I certainly see user namespaces like this as having the potential to make linux systems more secure.
- Zigurd 14y ago
  I don't know enough about the feature to say if it is applicable directly, but Android uses uid/gid to create sandboxes on a per-publisher basis, so that installed apps do not have access to other publishers' apps' files. This can be used in two ways: Application security, in general, would benefit from this practice, and if you are creating a Linux that can be both a traditional "desktop Linux" as well as running the Android environment, this is a useful feature for enabling Android app security to remain secure, which it wouldn't if you did user namespace separation merely by convention.
- shykes 14y ago
  Here's one use case: http://docker.io http://docker.io
wladimir 14y ago
It looks like the kernelnewbies.org page is getting stampeded and is unreachable. Too bad, they usually have a nice high-level overview of the new kernel features and changes.
- wazoox 14y ago
  If you can read french, http://linuxfr.org/news/sortie-du-noyau-linux-3-9 http://linuxfr.org/news/sortie-du-noyau-linux-3-9 is a good overview.
- edwintorok 14y ago
  The H also has an overview, but I usually prefer KernelNewbies too: http://www.h-online.com/open/features/What-s-new-in-Linux-3-9-1845705.html http://www.h-online.com/open/features/What-s-new-in-Linux-3-...
- iso8859-1 14y ago
  It's up now: http://kernelnewbies.org/LinuxChanges http://kernelnewbies.org/LinuxChanges
ippa 14y ago
Been waiting for raid5 with btrfs!
- kostya-kow 14y ago
  How stable is btrfs at this point?
  - xr09 14y ago
    They say we must wait a little longer...
  - ElliotH 14y ago
    I use it full time on my Desktop and my Laptop. It glitches fairly often but nothing unrecoverable. You'll mostly run into issues if you run out of space. Also there's some weird side effects with improper shut-down that you should note. Btrfs tends to leave some stuff in my logs too, but nothing that actually lost data, normally I see the error after a brief lockup in the system.
    - mpyne 14y ago
      On that note about running out of space, an interesting thing you have to keep in mind with btrfs is that, as a snapshotting filesystem you can't simply unlink files to free up space. They're still present and taking up space in a previous snapshot. There's ways to free up space for real but you have to manually use some tools to do it from what I understand.
    - iso8859-1 14y ago
      > glitches Panic? OOPS?
      - ElliotH 14y ago
        Mainly oops left in my logs, one or two panics on shutdown. Once a panic when I was doing something silly with my uni research project. Pity I can't report these really, tainted (AMD) kernel.
demetris 14y ago
From the first paragraph of the announcement:[1] “makes me suspect [...] people were gaming the system and had timed some of their pull requests for just before the release”. Does anyone know what Linus means by that? [1] http://lwn.net/Articles/548799/ http://lwn.net/Articles/548799/
- edwintorok 14y ago
  Pull requests this late in the -rc cycle should contain only important bugfixes, other changes should normally wait for the next kernel release. For example Linus ignored some pull requests sent for 3.6-rc2 that didn't really belong there: https://lkml.org/lkml/2012/8/16/577 https://lkml.org/lkml/2012/8/16/577
srisa 14y ago
Am I the only one who feels that the kernel releases have been more frequent during recent times? Or is it that they have changed the version numbering like firefox? About an year or so ago, it was something like 2.6.x. Then, it jumped to 3.0 and now it is at 3.9.
- andrewaylett 14y ago
  Linux jumped from 2.6.39 to 3.0 because the numbers were getting too big. He also decided that as the middle digit wasn't being incremented, he'd drop it.
  - srisa 14y ago
    I remember seeing 2.6.42 on my ubuntu 10.04. May be it was kind of an alias for some 3.x version.
    - jeltz 14y ago
      Yeah, some software assumed that there must be three digits in version numbers so 3.X kernels were sometimes called 2.6.X+40 which means 2.6.42 actually is 3.2.
  - coldpie 14y ago
    I really wish he would've gone with date-based version numbers. 3.X is eventually going to get "too big" and it will be the same (non-)problem.
- corbet 14y ago
  Kernel releases have been getting a bit more frequent. A couple of years ago they were about 80 days apart, now it's closer to 70. A change, but not a huge one.
- seanwoods 14y ago
  Agreed. It seems that the trajectory from 2.0 to 3.0 was much, much slower than the one from 3.0 to 4.0 (at least judging by data points so far). Anyone know of any reason for this?
freeman478 14y ago
Particularly interesting is the possibility of using a SSD as a cache for a HDD just like the Fusion Drive in the recent iMacs (https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/plain/Documentation/device-mapper/cache.txt?id=c6b4fcbad044e6fffcc75bba160e720eb8d67d17 https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux....) Reviews were quite positive of Apple implementation. Has anybody tried the linux version ?
- dsr_ 14y ago
  I've got flashcache running on a 20GB SSD partition fronting a 120GB spinning disk partition, on a desktop at home. It feels (anecdotal, subjective) as fast as a pure SSD for all normal desktop things. I also ran a small MySQL db through this setup for a few weeks, and that improved noticeably over a single spinning disk, especially when there was IO load from other processes. The install procedure is a little rough around the edges, so I'm looking forward to having that more polished.

99 points by edwintorok 14y ago

girvo 14y ago

I'm quite interested in the user namespaces feature, but can't come up with any use cases for myself other than say sandboxing (sort of) applications. Can anyone explain it a bit better? The lwn article is a bit heavy going

FooBarWidget 14y ago
It was primarily designed for sandboxing, so it's not strange that you cannot come up with other use cases.
- girvo 14y ago
  That... Would make sense then. Now I feel stupid ;)
gioele 14y ago
What about this other LWN article "A new approach to user namespaces": https://lwn.net/Articles/491310/ https://lwn.net/Articles/491310/ ? > It allows for applications with no capabilities to use multiple uids and to implement privilege separation. I certainly see user namespaces like this as having the potential to make linux systems more secure.
Zigurd 14y ago
I don't know enough about the feature to say if it is applicable directly, but Android uses uid/gid to create sandboxes on a per-publisher basis, so that installed apps do not have access to other publishers' apps' files. This can be used in two ways: Application security, in general, would benefit from this practice, and if you are creating a Linux that can be both a traditional "desktop Linux" as well as running the Android environment, this is a useful feature for enabling Android app security to remain secure, which it wouldn't if you did user namespace separation merely by convention.
shykes 14y ago
Here's one use case: http://docker.io http://docker.io

wladimir 14y ago

It looks like the kernelnewbies.org page is getting stampeded and is unreachable. Too bad, they usually have a nice high-level overview of the new kernel features and changes.

wazoox 14y ago
If you can read french, http://linuxfr.org/news/sortie-du-noyau-linux-3-9 http://linuxfr.org/news/sortie-du-noyau-linux-3-9 is a good overview.
edwintorok 14y ago
The H also has an overview, but I usually prefer KernelNewbies too: http://www.h-online.com/open/features/What-s-new-in-Linux-3-9-1845705.html http://www.h-online.com/open/features/What-s-new-in-Linux-3-...
iso8859-1 14y ago
It's up now: http://kernelnewbies.org/LinuxChanges http://kernelnewbies.org/LinuxChanges

ippa 14y ago

Been waiting for raid5 with btrfs!

kostya-kow 14y ago
How stable is btrfs at this point?
- xr09 14y ago
  They say we must wait a little longer...
- ElliotH 14y ago
  I use it full time on my Desktop and my Laptop. It glitches fairly often but nothing unrecoverable. You'll mostly run into issues if you run out of space. Also there's some weird side effects with improper shut-down that you should note. Btrfs tends to leave some stuff in my logs too, but nothing that actually lost data, normally I see the error after a brief lockup in the system.
  - mpyne 14y ago
    On that note about running out of space, an interesting thing you have to keep in mind with btrfs is that, as a snapshotting filesystem you can't simply unlink files to free up space. They're still present and taking up space in a previous snapshot. There's ways to free up space for real but you have to manually use some tools to do it from what I understand.
  - iso8859-1 14y ago
    > glitches Panic? OOPS?
    - ElliotH 14y ago
      Mainly oops left in my logs, one or two panics on shutdown. Once a panic when I was doing something silly with my uni research project. Pity I can't report these really, tainted (AMD) kernel.

demetris 14y ago

From the first paragraph of the announcement:[1] “makes me suspect [...] people were gaming the system and had timed some of their pull requests for just before the release”. Does anyone know what Linus means by that? [1] http://lwn.net/Articles/548799/ http://lwn.net/Articles/548799/

edwintorok 14y ago
Pull requests this late in the -rc cycle should contain only important bugfixes, other changes should normally wait for the next kernel release. For example Linus ignored some pull requests sent for 3.6-rc2 that didn't really belong there: https://lkml.org/lkml/2012/8/16/577 https://lkml.org/lkml/2012/8/16/577

srisa 14y ago

Am I the only one who feels that the kernel releases have been more frequent during recent times? Or is it that they have changed the version numbering like firefox? About an year or so ago, it was something like 2.6.x. Then, it jumped to 3.0 and now it is at 3.9.

andrewaylett 14y ago
Linux jumped from 2.6.39 to 3.0 because the numbers were getting too big. He also decided that as the middle digit wasn't being incremented, he'd drop it.
- srisa 14y ago
  I remember seeing 2.6.42 on my ubuntu 10.04. May be it was kind of an alias for some 3.x version.
  - jeltz 14y ago
    Yeah, some software assumed that there must be three digits in version numbers so 3.X kernels were sometimes called 2.6.X+40 which means 2.6.42 actually is 3.2.
- coldpie 14y ago
  I really wish he would've gone with date-based version numbers. 3.X is eventually going to get "too big" and it will be the same (non-)problem.
corbet 14y ago
Kernel releases have been getting a bit more frequent. A couple of years ago they were about 80 days apart, now it's closer to 70. A change, but not a huge one.
seanwoods 14y ago
Agreed. It seems that the trajectory from 2.0 to 3.0 was much, much slower than the one from 3.0 to 4.0 (at least judging by data points so far). Anyone know of any reason for this?

freeman478 14y ago

Particularly interesting is the possibility of using a SSD as a cache for a HDD just like the Fusion Drive in the recent iMacs (https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/plain/Documentation/device-mapper/cache.txt?id=c6b4fcbad044e6fffcc75bba160e720eb8d67d17 https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux....) Reviews were quite positive of Apple implementation. Has anybody tried the linux version ?

dsr_ 14y ago
I've got flashcache running on a 20GB SSD partition fronting a 120GB spinning disk partition, on a desktop at home. It feels (anecdotal, subjective) as fast as a pure SSD for all normal desktop things. I also ran a small MySQL db through this setup for a few weeks, and that improved noticeably over a single spinning disk, especially when there was IO load from other processes. The install procedure is a little rough around the edges, so I'm looking forward to having that more polished.