| Message ID | 20221004024157.2470238-4-joel@joelfernandes.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | rcu: call_rcu() power improvements | expand |
On Tue, Oct 04, 2022 at 02:41:49AM +0000, Joel Fernandes (Google) wrote: > This consolidates the code a bit and makes it cleaner. Functionally it > is the same. > > Reported-by: Paul E. McKenney <paulmck@kernel.org> > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> > --- > kernel/rcu/tree_nocb.h | 17 +++++++++-------- > 1 file changed, 9 insertions(+), 8 deletions(-) > > diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h > index 56616bfbe156..dfa736da68ab 100644 > --- a/kernel/rcu/tree_nocb.h > +++ b/kernel/rcu/tree_nocb.h > @@ -327,10 +327,11 @@ static void wake_nocb_gp_defer(struct rcu_data *rdp, int waketype, > * > * Note that this function always returns true if rhp is NULL. > */ > -static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp, > +static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp_in, > unsigned long j, bool lazy) > { > struct rcu_cblist rcl; > + struct rcu_head *rhp = rhp_in; > > WARN_ON_ONCE(!rcu_rdp_is_offloaded(rdp)); > rcu_lockdep_assert_cblist_protected(rdp); > @@ -345,16 +346,16 @@ static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp, > > /* > * If the new CB requested was a lazy one, queue it onto the main > - * ->cblist so we can take advantage of a sooner grade period. > + * ->cblist so that we can take advantage of the grace-period that will > + * happen regardless. But queue it onto the bypass list first so that > + * the lazy CB is ordered with the existing CBs in the bypass list. > */ > if (lazy && rhp) { > - rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, NULL); > - rcu_cblist_enqueue(&rcl, rhp); > - WRITE_ONCE(rdp->lazy_len, 0); > - } else { > - rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, rhp); > - WRITE_ONCE(rdp->lazy_len, 0); > + rcu_cblist_enqueue(&rdp->nocb_bypass, rhp); > + rhp = NULL; > } > + rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, rhp); > + WRITE_ONCE(rdp->lazy_len, 0); Much much better, thank you! Thanx, Paul > rcu_segcblist_insert_pend_cbs(&rdp->cblist, &rcl); > WRITE_ONCE(rdp->nocb_bypass_first, j); > -- > 2.38.0.rc1.362.ged0d419d3c-goog >
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index 56616bfbe156..dfa736da68ab 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -327,10 +327,11 @@ static void wake_nocb_gp_defer(struct rcu_data *rdp, int waketype, * * Note that this function always returns true if rhp is NULL. */ -static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp, +static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp_in, unsigned long j, bool lazy) { struct rcu_cblist rcl; + struct rcu_head *rhp = rhp_in; WARN_ON_ONCE(!rcu_rdp_is_offloaded(rdp)); rcu_lockdep_assert_cblist_protected(rdp); @@ -345,16 +346,16 @@ static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp, /* * If the new CB requested was a lazy one, queue it onto the main - * ->cblist so we can take advantage of a sooner grade period. + * ->cblist so that we can take advantage of the grace-period that will + * happen regardless. But queue it onto the bypass list first so that + * the lazy CB is ordered with the existing CBs in the bypass list. */ if (lazy && rhp) { - rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, NULL); - rcu_cblist_enqueue(&rcl, rhp); - WRITE_ONCE(rdp->lazy_len, 0); - } else { - rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, rhp); - WRITE_ONCE(rdp->lazy_len, 0); + rcu_cblist_enqueue(&rdp->nocb_bypass, rhp); + rhp = NULL; } + rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, rhp); + WRITE_ONCE(rdp->lazy_len, 0); rcu_segcblist_insert_pend_cbs(&rdp->cblist, &rcl); WRITE_ONCE(rdp->nocb_bypass_first, j);
This consolidates the code a bit and makes it cleaner. Functionally it is the same. Reported-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> --- kernel/rcu/tree_nocb.h | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)