Re: tty's use of file_list_lock and file_move

["Jon Smirl" <jonsmirl@gmail.com>]

On 7/10/06, Theodore Tso <tytso@mit.edu> wrote:
> On Mon, Jul 10, 2006 at 07:49:31PM -0400, Jon Smirl wrote:
> > How about the use of lock/unlock_kernel(). Is there some hidden global
> > synchronization going on? Every time lock/unlock_kernel() is used
> > there is a tty_struct available. My first thought would be to turn
> > this into a per tty spinlock. Looking at where it is used it looks
> > like it was added to protect all of the VFS calls. I see no obvious
> > coordination with other ttys that isn't handled by other locks.
>
> No, it was just a case of not being worth it to get rid of the BKL for
> the tty subsystem, since opening and closing tty's isn't exactly a
> common event.  Switching it to use a per-tty spinlock makes sense if
> we're going to rototill the code, but to be honest it's probably not
> going to make a noticeable difference on any benchmark and most
> workloads.

I'm not looking for performance gains, I'm looking more to isolate the
tty code down to a minimal set of interactions with the rest of the
kernel. RIght now it is all intertwined.

--
Jon Smirl
jonsmirl@gmail.com
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