Messages in this thread | | | Date | Tue, 26 Jun 2007 07:53:09 -0700 | From | "Paul E. McKenney" <> | Subject | Re: synchronize_qrcu_timeout() |
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On Mon, Jun 25, 2007 at 07:49:57PM +0400, Oleg Nesterov wrote: > On 06/25, Oleg Nesterov wrote: > > > > On 06/25, Paul E. McKenney wrote: > > > > > > On Mon, Jun 25, 2007 at 02:43:32PM +0400, Oleg Nesterov wrote: > > > > > > > > Sadly, you can't use srcu/qrcu because it doesn't handle timeouts. > > > > > > Interesting... So the thought is to have a synchronize_srcu_timeout() > > > or something similar that waited for a grace period to elapse or for > > > a timeout to expire, whichever comes first? It should not be too hard > > > to arrange something, if needed. > > > > Yes. As for qrcu (see http://marc.info/?t=116484476500001), I think it is easy. > > First, we add "int interrupted" into struct qrcu_struct, then something like this > > Even simpler, we don't need ->interrupted.
I have to ask...
What sorts of performance characteristics are needed here? The reason that I ask is because putting a straight synchronize_qrcu() into a workqueue (or something similar) and then using a timer to provide any needed wakeup seems a lot simpler than rearranging the innards of synchronize_qrcu().
(Yes, I am feeling cowardly. Why do you ask?)
Thanx, Paul
> long synchronize_qrcu_timeout(struct qrcu_struct *qp, long tout) > { > int idx, prv; > > smp_mb(); > mutex_lock(&qp->mutex); > > idx = qp->completed & 0x1; > prv = idx ^ 0x1; > > if (unlikely(atomic_read(qp->ctr + prv))) { > // the previous call has not succeed, > // finish the wait > __wait_event_timeout(qp->wq, !atomic_read(qp->ctr + prv), tout); > if (unlikely(!tout)) > goto out; > } > > if (atomic_read(qp->ctr + idx) == 1) > goto out; > > atomic_inc(qp->ctr + prv); > qp->completed++; > > atomic_dec(qp->ctr + idx); > __wait_event_timeout(qp->wq, !atomic_read(qp->ctr + idx), tout); > out: > mutex_unlock(&qp->mutex); > smp_mb(); > > return tout; > } > > Oleg. > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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