Messages in this thread |  | | | Date | Wed, 14 May 2008 14:56:37 -0700 (PDT) | | From | Linus Torvalds <> | | Subject | Re: [announce] "kill the Big Kernel Lock (BKL)" tree | |
On Wed, 14 May 2008, Jonathan Corbet wrote:
>
> There's also every char device open() method - a rather long list in its
> own right. I'd be surprised if one in ten of them really needs it, but
> one has to look...
I don't think there are *that* many. I found only 83 instances of
"register_chrdev()" in the kernel, so the open methods should be pretty
limited.
Of course, some open methods call other sub-registrations, but you'd start
off by moving the lock_kernel() down just *one* stage.
So it literally should be:
- remove one lock_kernel/unlock_kernel pair in fs/char_dev.c
- add max 83 pairs in the places that register those things
- external modules will need to add it themselves some day.
> 1: We could add an unlocked_open() to the file_operations structure;
> drivers could be converted over as they are verified not to need the
> BKL on open. Disadvantages are that it grows this structure for a
> relatively rare case - most open() calls already don't need the BKL.
> But it's a relatively easy path without flag days.
I really don't think it's worth the pain. See above. The numbers aren't
that huge, and external modules simply aren't a pressing enough issue.
Linus
|  |