Paravirt spinlock clears slowpath flag after doing unlock.
As explained by Linus currently it does:
prev = *lock;
add_smp(lock-tickets.head, TICKET_LOCK_INC);
/* add_smp() is a full mb() */
if (unlikely(lock-tickets.tail
On 02/12/2015 07:20 PM, Oleg Nesterov wrote:
On 02/12, Raghavendra K T wrote:
@@ -191,8 +189,7 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t
*lock)
* We need to check unlocked in a loop, tmp.head == head
* can be false positive because of
On 02/12/2015 07:32 PM, Oleg Nesterov wrote:
Damn, sorry for noise, forgot to mention...
On 02/12, Raghavendra K T wrote:
+static inline void __ticket_check_and_clear_slowpath(arch_spinlock_t *lock,
+ __ticket_t head)
+{
+ if (head
Damn, sorry for noise, forgot to mention...
On 02/12, Raghavendra K T wrote:
+static inline void __ticket_check_and_clear_slowpath(arch_spinlock_t *lock,
+ __ticket_t head)
+{
+ if (head TICKET_SLOWPATH_FLAG) {
+
On 02/12/2015 07:07 PM, Oleg Nesterov wrote:
On 02/12, Raghavendra K T wrote:
@@ -772,7 +773,8 @@ __visible void kvm_lock_spinning(struct arch_spinlock
*lock, __ticket_t want)
* check again make sure it didn't become free while
* we weren't looking.
*/
- if
On 02/12, Raghavendra K T wrote:
@@ -191,8 +189,7 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t
*lock)
* We need to check unlocked in a loop, tmp.head == head
* can be false positive because of overflow.
*/
- if
On Thu, Feb 12, 2015 at 05:17:27PM +0530, Raghavendra K T wrote:
Paravirt spinlock clears slowpath flag after doing unlock.
As explained by Linus currently it does:
prev = *lock;
add_smp(lock-tickets.head, TICKET_LOCK_INC);
/* add_smp() is a
On 02/12/2015 08:30 PM, Peter Zijlstra wrote:
On Thu, Feb 12, 2015 at 05:17:27PM +0530, Raghavendra K T wrote:
[...]
Linus suggested that we should not do any writes to lock after unlock(),
and we can move slowpath clearing to fastpath lock.
So this patch implements the fix with:
1. Moving
