On 05/08/2014 03:12 PM, Peter Zijlstra wrote:
On Wed, May 07, 2014 at 11:01:38AM -0400, Waiman Long wrote:
No, we want the unfair thing for VIRT, not PARAVIRT.
Yes, you are right. I will change that to VIRT.
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index
(tl;dr: paravirtualization could be better than unfair qspinlock)
2014-05-07 11:01-0400, Waiman Long:
Locking is always an issue in a virtualized environment because of 2
different types of problems:
1) Lock holder preemption
2) Lock waiter preemption
Paravirtualized ticketlocks have a
On Wed, May 07, 2014 at 11:01:38AM -0400, Waiman Long wrote:
No, we want the unfair thing for VIRT, not PARAVIRT.
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 9e7659e..10e87e1 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -227,6
Locking is always an issue in a virtualized environment because of 2
different types of problems:
1) Lock holder preemption
2) Lock waiter preemption
One solution to the lock waiter preemption problem is to allow unfair
lock in a virtualized environment. In this case, a new lock acquirer
can
