Re: [PATCH 1/5] rcu: uninline __rcu_pending()

Paul E. McKenney
2006-01-09T17:20:31Z

On Sun, Jan 08, 2006 at 10:19:16PM +0300, Oleg Nesterov wrote:
> __rcu_pending() is rather fat and called twice from rcu_pending().
>
> rcu_pending() has multiple callers, and not that small too.
>
> This patch uninlines both of them.

Looks good -- I must defer to Dipankar on any performance problems, but
I would not expect any this far off of the fastpaths. Also makes
handling multiple different RCU implementations a bit easier on the
eyes.

Thanx, Paul

Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
> Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
>
> --- 2.6.15/include/linux/rcupdate.h~1_OUTL 2006-01-03 21:15:58.000000000 +0300
> +++ 2.6.15/include/linux/rcupdate.h 2006-01-08 21:36:07.000000000 +0300
> @@ -125,36 +125,7 @@ static inline void rcu_bh_qsctr_inc(int
> rdp->passed_quiesc = 1;
> }
>
> -static inline int __rcu_pending(struct rcu_ctrlblk *rcp,
> - struct rcu_data *rdp)
> -{
> - /* This cpu has pending rcu entries and the grace period
> - * for them has completed.
> - */
> - if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch))
> - return 1;
> -
> - /* This cpu has no pending entries, but there are new entries */
> - if (!rdp->curlist && rdp->nxtlist)
> - return 1;
> -
> - /* This cpu has finished callbacks to invoke */
> - if (rdp->donelist)
> - return 1;
> -
> - /* The rcu core waits for a quiescent state from the cpu */
> - if (rdp->quiescbatch != rcp->cur || rdp->qs_pending)
> - return 1;
> -
> - /* nothing to do */
> - return 0;
> -}
> -
> -static inline int rcu_pending(int cpu)
> -{
> - return __rcu_pending(&rcu_ctrlblk, &per_cpu(rcu_data, cpu)) ||
> - __rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu));
> -}
> +extern int rcu_pending(int cpu);
>
> /**
> * rcu_read_lock - mark the beginning of an RCU read-side critical section.
> --- 2.6.15/kernel/rcupdate.c~1_OUTL 2006-01-03 21:15:58.000000000 +0300
> +++ 2.6.15/kernel/rcupdate.c 2006-01-08 21:35:21.000000000 +0300
> @@ -442,6 +442,36 @@ static void rcu_process_callbacks(unsign
> &__get_cpu_var(rcu_bh_data));
> }
>
> +static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp)
> +{
> + /* This cpu has pending rcu entries and the grace period
> + * for them has completed.
> + */
> + if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch))
> + return 1;
> +
> + /* This cpu has no pending entries, but there are new entries */
> + if (!rdp->curlist && rdp->nxtlist)
> + return 1;
> +
> + /* This cpu has finished callbacks to invoke */
> + if (rdp->donelist)
> + return 1;
> +
> + /* The rcu core waits for a quiescent state from the cpu */
> + if (rdp->quiescbatch != rcp->cur || rdp->qs_pending)
> + return 1;
> +
> + /* nothing to do */
> + return 0;
> +}
> +
> +int rcu_pending(int cpu)
> +{
> + return __rcu_pending(&rcu_ctrlblk, &per_cpu(rcu_data, cpu)) ||
> + __rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu));
> +}
> +
> void rcu_check_callbacks(int cpu, int user)
> {
> if (user ||
>