Linux 3.9 Released 112
hypnosec writes "After a week's delay Linux 3.9 has finally been made available by Linus Torvalds. Last week Torvalds released the rc8 stating that he wasn't 'comfy' releasing the final version yet and that 'another week won't hurt.' Torvalds noted in this week's announcement that last week had been very quiet as there were not many commits and the ones which were there were 'really tiny' so he went ahead with the release of Linux 3.9."
Interesting but... (Score:5, Interesting)
on dm-cache, bcache, etc (Score:5, Interesting)
Thanks for the link. I chased down the dm-cache stuff a bit, looking at it vs. bcache, which we'll see in June, probably. The primary differences seem to be that dm-cache is a bit more generic and easier to work with and it allows some manual allocation of the different types of disk data to be cached, while bcache seems to be targeting SSD's specifically, with wear-leveling sensitive write patterns, use of TRIM, and in-kernel code to validate the cache drives for preventing stupid user tricks.
EnhanceIO might also be targeting 3.10, which is a descendant of flashcache, which uses the layered device approach, while dm-cache and bcache are side-loaded. EnhanceIO uses udev rather than in-kernel code to prevent the stupid user tricks. I got the sense that 3.10 was possible for EnhanceIO but not as certain as bcache.
I'm current using flashcache on my non-ZFS systems; it looks like I'll be waiting for 3.10 and use bcache for my next upgrade.
Re:These version numbers are getting like Firefox (Score:4, Interesting)
Honestly I think there have been more interesting developments along the way in 3.x than there were from 2.4 -> 2.6.
I totally agree, but it's also fair to say that the efforts towards correctness from 2.4 to 2.6 have enabled the feature work happening in 3.x. I was just reading through the Xen commit about the feature to hot-plug new memory and CPU devices, and it's really so dependent on linux being able to say, "oh, you have a new memory module? OK, fine." which wasn't always the case.
And now for the flame-inducing observation: I think that through much of the 2000's, the BSD folks had a more mature and correct operating system to build on and that allowed them to add new features (e.g. pf, jails, zfs, dtrace) in an easier and faster way and we greatly benefited from that during that time period. Sure, linux had more drivers, but there was a fair bit of ugly kernel code to be faced. As of some point in the past couple years, linux has caught up, and now most of the really interesting new stuff (e.g. user namespaces) is probably going to be on linux, as that's where the momentum is. It'll probably be another three years before this becomes really obvious. Certainly there are still parts of linux with ugliness that need some TLC - I'm just talking about an inflection point, not an endpoint.
Re:on dm-cache, bcache, etc (Score:4, Interesting)
bcache can't be side-loaded though. :-( You need to format the HDD for bcache you can add/remove the SSD whatever you want after that though. But I expect bcache to be the fastest. As an indication the developer also needed to change/optimize parts of the block layer in the kernel before bcache could be added.