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2.6.27-rc1, "Pretty Dang Busy"

By Jeremy
Created Jul 29 2008 - 19:18

"It's two weeks (and one day), and the merge window is over," began Linus Torvalds, announcing the 2.6.27-rc1 kernel. He continued, "finally. I don't know why, but this one really did feel pretty dang busy. And the size of the -rc1 patch bears that out - at 12MB, it's about 50% bigger than 26-rc1 (but not that much bigger than 24/25-rc1, so it's not like it's anything unheard of)." He reflected, "the pure size of the -rc's _is_ making me a bit nervous, though. Sure, it means that we are good at merging it all, but I have to say that I sometimes wonder if we don't merge too much in one go, and even our current (fairly short) release cycle is actually too big." As for the actual changes, Linus explained:

"Much of -rc1 was in linux-next, but certainly not everything. We'll see how that whole thing ends up evolving - it certainly didn't solve all problems, and there was some bickering about things that weren't there (and some things that mostly were ;), but maybe it helped. There's a ton of new stuff in there, but at least personally the interesting things are the BKL pushdown and perhaps the introduction of the lockless get_user_pages_fast(). The build system also got updated to allow moving the architecture include files ('include/asm-xyz') into the architecture subdirectories ('arch/xyz/include/asm'), and sparc seems to have taken advantage of that already."

Other changes Linus highlighted included merging the UBI filesystem, as well as, "tracing, firmware loading, continued x86 arch merging, and moving more code to generic support (unified generic IPI handling, coherent dma memory allocation, show_mem etc). Bootmem rewrites. [And] some support for further scalability (ie 4k cpu cores)."


From: Linus Torvalds <torvalds@...>
Subject: Linux v2.6.27-rc1
 [0]Date: Jul 28, 11:23 pm 2008

It's two weeks (and one day), and the merge window is over.

Finally. I don't know why, but this one really did feel pretty dang busy. 
And the size of the -rc1 patch bears that out - at 12MB, it's about 50% 
bigger than 26-rc1 (but not that much bigger than 24/25-rc1, so it's not 
like it's anything unheard of).

The pure size of the -rc's _is_ making me a bit nervous, though. Sure, it 
means that we are good at merging it all, but I have to say that I 
sometimes wonder if we don't merge too much in one go, and even our 
current (fairly short) release cycle is actually too big.

Anyway, that's a discussion for some other event.

Much of -rc1 was in linux-next, but certainly not everything. We'll see 
how that whole thing ends up evolving - it certainly didn't solve all 
problems, and there was some bickering about things that weren't there 
(and some things that mostly were ;), but maybe it helped.

There's a ton of new stuff in there, but at least personally the 
interesting things are the BKL pushdown and perhaps the introduction of 
the lockless get_user_pages_fast(). The build system also got updated to 
allow moving the architecture include files ("include/asm-xyz") into the 
architecture subdirectories ("arch/xyz/include/asm"), and sparc seems to 
have taken advantage of that already.

But those changes are just small details in the end. As usual, the bulk of 
changes are all to device drivers (roughly half, as usual), with the arch 
directory amounting to about half of the remainder. Dirstat:

   3.2% arch/arm/
   9.2% arch/ppc/
  24.6% arch/
   5.2% drivers/char/drm/
   6.3% drivers/char/
   4.5% drivers/gpu/drm/
   4.5% drivers/gpu/
   4.6% drivers/media/video/
   5.5% drivers/media/
   3.0% drivers/net/wireless/
  10.7% drivers/net/
   6.4% drivers/usb/misc/
   4.7% drivers/usb/serial/
  12.9% drivers/usb/
  51.2% drivers/
   4.4% firmware/
   3.7% fs/
   9.2% include/

where the bulk of that fs/ update is the merge of the UBI filesystem, to 
pick one fairly sizeable chunk outside of arch or drivers (there's omfs 
too, but that's tiny in comparison).

Other stuff? tracing. firmware loading. continued x86 arch merging. And 
moving more code to generic support (unified generic IPI handling, 
coherent dma memory allocation, show_mem etc). bootmem rewrites. Some 
support for further scalability (ie 4k cpu cores).

But mostly lots and lots of driver and arch updates.

Go to kernelnewbies or lwn for more reporting, I'm going to sleep for 
twenty-four hours now ;)

			Linus
--


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