On Wed, Feb 03, 2016 at 04:42:23PM +0900, Sergey Senozhatsky wrote: > On (02/03/16 08:28), Ingo Molnar wrote: > [..] > > So why not move printk away from semaphores? Semaphores are classical > > constructs > > that have legacies and are somewhat non-obvious to use, compared to modern, > > simpler locking primitives. I'd not touch their implementation, unless we > > are > > absolutely sure this is a safe optimization. > > semaphore's spin_lock is not the only spin lock that printk acquires. it also > takes the > logbuf_lock (and different locks in console drivers (up to console driver)). > > Jan Kara posted a patch that offloads printing job > (console_trylock()-console_unlock()) > from printk() call (when printk can offload it). so semaphore and console > driver's locks > will go away (mostly) with Jan's patch. logbug spin_lock, however, will stay.
It sounds good. Could you teach me how to see the patch by Jan? > > -ss
