Displaying 5 results from an estimated 5 matches for "_subtracts_".
2014 Jun 23
1
[PATCH 01/11] qspinlock: A simple generic 4-byte queue spinlock
..., the lock as a whole is contended (there's >1 waiters), and the
point of MCS style locks it to make sure they're not actually pounding
on the same cacheline. So the whole thing is consistent.
> Perhaps you could add this comment.
>
> /* Once queue_spin_unlock is called (which _subtracts_ _Q_LOCKED_VAL from
> the lock->val and still preserving the tail data), the winner gets to
> claim the ticket.
There's no tickets :/
> Since we still need the other CPUs to continue and
> preserve the strict ordering in which they setup node->next, we:
> 1) update lock-...
2014 Jun 23
1
[PATCH 01/11] qspinlock: A simple generic 4-byte queue spinlock
..., the lock as a whole is contended (there's >1 waiters), and the
point of MCS style locks it to make sure they're not actually pounding
on the same cacheline. So the whole thing is consistent.
> Perhaps you could add this comment.
>
> /* Once queue_spin_unlock is called (which _subtracts_ _Q_LOCKED_VAL from
> the lock->val and still preserving the tail data), the winner gets to
> claim the ticket.
There's no tickets :/
> Since we still need the other CPUs to continue and
> preserve the strict ordering in which they setup node->next, we:
> 1) update lock-...
2014 Jun 17
0
[PATCH 01/11] qspinlock: A simple generic 4-byte queue spinlock
...me off. Somehow
I imagined there are two more more CPUs stampeding here and
trying to update the lock->val. But in reality the other CPUs
are stuck in the arch_mcs_spin_lock_contended spinning on their
local value.
Perhaps you could add this comment.
/* Once queue_spin_unlock is called (which _subtracts_ _Q_LOCKED_VAL from
the lock->val and still preserving the tail data), the winner gets to
claim the ticket. Since we still need the other CPUs to continue and
preserve the strict ordering in which they setup node->next, we:
1) update lock->val to the tail value (so tail CPU and its index)...
2014 Jun 16
4
[PATCH 01/11] qspinlock: A simple generic 4-byte queue spinlock
On Sun, Jun 15, 2014 at 02:46:58PM +0200, Peter Zijlstra wrote:
> From: Waiman Long <Waiman.Long at hp.com>
>
> This patch introduces a new generic queue spinlock implementation that
> can serve as an alternative to the default ticket spinlock. Compared
> with the ticket spinlock, this queue spinlock should be almost as fair
> as the ticket spinlock. It has about the same
2014 Jun 16
4
[PATCH 01/11] qspinlock: A simple generic 4-byte queue spinlock
On Sun, Jun 15, 2014 at 02:46:58PM +0200, Peter Zijlstra wrote:
> From: Waiman Long <Waiman.Long at hp.com>
>
> This patch introduces a new generic queue spinlock implementation that
> can serve as an alternative to the default ticket spinlock. Compared
> with the ticket spinlock, this queue spinlock should be almost as fair
> as the ticket spinlock. It has about the same