Re: [announce] "kill the Big Kernel Lock (BKL)" tree

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To: Alan Cox <alan@...>
Cc: Andi Kleen <andi@...>, Ingo Molnar <mingo@...>, <linux-kernel@...>, Andrew Morton <akpm@...>, Peter Zijlstra <a.p.zijlstra@...>, Thomas Gleixner <tglx@...>, Alexander Viro <viro@...>
Date: Wednesday, May 14, 2008 - 5:45 pm

On Wed, 14 May 2008, Alan Cox wrote:

The good news is that I suspect they are going away. It probably is mainly 
tty and /proc by now, and /proc is pretty close to done.

It's hard to have too many inter-module dependencies when most of the core 
modules no longer even take the kernel lock any more.

In the VFS layer, we still have 

 - the ioctl thing, obviously. That's just mind-numbing "move things 
   down", not hard per se. But there's a *lot* of them (and I suspect the 
   huge majority of them don't actually need it, since they'd already be 
   racing against read/write anyway if they did).

 - default_llseek(). Probably the same, just a lot less of it.

 - superblock read/write.

and the latter one in particular is really dubious (we already have 
"[un]lock_super()" around it all, I think).

The core kernel, VM and networking already don't really do BKL. And it's 
seldom the case that subsystems interact with other unrelated subsystems 
outside of the core areas.

So it's a lot of work, no doubt, but I do think we should be able to do 
it. The most mind-numbing part is literally all the ioctl crud. There's 
more ioctl points than there are lock_kernel() calls left anywhere else.

		Linus
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Messages in current thread:
[announce] "kill the Big Kernel Lock (BKL)" tree, Ingo Molnar, (Wed May 14, 1:49 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Linus Torvalds, (Thu May 15, 1:41 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Arjan van de Ven, (Thu May 15, 4:27 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Peter Zijlstra, (Thu May 15, 4:45 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Arjan van de Ven, (Thu May 15, 5:22 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Linus Torvalds, (Wed May 14, 2:41 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Ingo Molnar, (Wed May 14, 3:41 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Frederik Deweerdt, (Wed May 14, 4:05 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Wed May 14, 2:30 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Wed May 14, 5:13 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, H. Peter Anvin, (Wed May 14, 5:16 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Linus Torvalds, (Wed May 14, 5:45 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Wed May 14, 6:03 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Thu May 15, 10:27 am)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Fri May 16, 6:21 am)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Ingo Molnar, (Thu May 15, 4:02 am)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree , Jonathan Corbet, (Wed May 14, 5:45 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree , Jan Engelhardt, (Thu May 15, 4:44 am)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Diego Calleja, (Thu May 15, 10:54 am)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree , Linus Torvalds, (Wed May 14, 5:56 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree , Jonathan Corbet, (Wed May 14, 6:07 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree , Linus Torvalds, (Wed May 14, 6:14 pm)
[PATCH, RFC] char dev BKL pushdown , Jonathan Corbet, (Fri May 16, 11:44 am)
Re: [PATCH, RFC] char dev BKL pushdown , Linus Torvalds, (Sat May 17, 5:58 pm)
Re: [PATCH, RFC] char dev BKL pushdown , Jonathan Corbet, (Sun May 18, 4:07 pm)
Re: [PATCH, RFC] char dev BKL pushdown , Linus Torvalds, (Fri May 16, 12:30 pm)
Re: [PATCH, RFC] char dev BKL pushdown , Jonathan Corbet, (Fri May 16, 12:43 pm)
Re: [PATCH, RFC] char dev BKL pushdown, Arnd Bergmann, (Sat May 17, 5:15 pm)
Re: [PATCH, RFC] char dev BKL pushdown , Jonathan Corbet, (Sun May 18, 4:26 pm)
Re: [PATCH, RFC] char dev BKL pushdown, Arnd Bergmann, (Mon May 19, 7:07 pm)
Re: [PATCH, RFC] char dev BKL pushdown , Jonathan Corbet, (Tue May 20, 11:13 am)
Re: [PATCH, RFC] char dev BKL pushdown, Arnd Bergmann, (Tue May 20, 1:21 pm)
Re: [PATCH, RFC] char dev BKL pushdown, Alan Cox, (Tue May 20, 2:51 pm)
[PATCH 1/3, RFC] misc char dev BKL pushdown, Arnd Bergmann, (Mon May 19, 7:26 pm)
Re: [PATCH 1/3, RFC] misc char dev BKL pushdown, Mike Frysinger, (Tue May 20, 7:01 pm)
Re: [PATCH 1/3, RFC] misc char dev BKL pushdown , Jonathan Corbet, (Tue May 20, 7:25 pm)
Re: [PATCH 1/3, RFC] misc char dev BKL pushdown, Mike Frysinger, (Wed May 21, 12:22 pm)
Re: [PATCH 1/3, RFC] misc char dev BKL pushdown, Alan Cox, (Tue May 20, 4:46 am)
Re: [PATCH 1/3, RFC] misc char dev BKL pushdown, Mike Frysinger, (Mon May 19, 8:07 pm)
Re: [PATCH 1/3, RFC] misc char dev BKL pushdown , Jonathan Corbet, (Mon May 19, 8:21 pm)
Re: [PATCH 1/3, RFC] misc char dev BKL pushdown, Mike Frysinger, (Mon May 19, 8:46 pm)
[PATCH 3/3, RFC] remove BKL from misc_open(), Arnd Bergmann, (Mon May 19, 7:34 pm)
Re: [PATCH, RFC] char dev BKL pushdown, Alan Cox, (Fri May 16, 12:22 pm)
Re: [PATCH, RFC] char dev BKL pushdown, Christoph Hellwig, (Fri May 16, 11:49 am)
[PATCH] kill empty chardev open/release methods, Christoph Hellwig, (Fri May 16, 12:03 pm)
Re: [PATCH] kill empty chardev open/release methods , Jonathan Corbet, (Sun May 18, 3:46 pm)
Re: [PATCH] kill empty chardev open/release methods, Alan Cox, (Fri May 16, 12:24 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Wed May 14, 6:11 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Linus Torvalds, (Wed May 14, 6:16 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Wed May 14, 6:21 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, John Stoffel, (Thu May 15, 11:05 am)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Thu May 15, 11:10 am)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, John Stoffel, (Thu May 15, 11:18 am)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Thu May 15, 11:45 am)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Kevin Winchester, (Fri May 16, 8:14 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Kevin Winchester, (Fri May 16, 8:37 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Linus Torvalds, (Wed May 14, 6:11 pm)
Re: [announce] "kill the Big Kernel Lock (BKL)" tree, Andi Kleen, (Wed May 14, 6:15 pm)