• Waiman Long's avatar
    locking/pvqspinlock: Implement simple paravirt support for the qspinlock · a23db284
    Waiman Long authored
    Provide a separate (second) version of the spin_lock_slowpath for
    paravirt along with a special unlock path.
    
    The second slowpath is generated by adding a few pv hooks to the
    normal slowpath, but where those will compile away for the native
    case, they expand into special wait/wake code for the pv version.
    
    The actual MCS queue can use extra storage in the mcs_nodes[] array to
    keep track of state and therefore uses directed wakeups.
    
    The head contender has no such storage directly visible to the
    unlocker.  So the unlocker searches a hash table with open addressing
    using a simple binary Galois linear feedback shift register.
    Suggested-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: default avatarWaiman Long <Waiman.Long@hp.com>
    Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Daniel J Blueman <daniel@numascale.com>
    Cc: David Vrabel <david.vrabel@citrix.com>
    Cc: Douglas Hatch <doug.hatch@hp.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: Paolo Bonzini <paolo.bonzini@gmail.com>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Scott J Norton <scott.norton@hp.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/1429901803-29771-9-git-send-email-Waiman.Long@hp.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    a23db284
qspinlock.c 12.2 KB