Messages in this thread | | | Date | Thu, 15 Dec 2016 12:04:59 +0000 | From | Mark Rutland <> | Subject | Re: [RFC v2 4/5] rcu: Use for_each_leaf_node_cpu() in force_qs_rnp() |
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On Thu, Dec 15, 2016 at 10:42:03AM +0800, Boqun Feng wrote: > ->qsmask of an RCU leaf node is usually more sparse than the > corresponding cpu_possible_mask. So replace the > for_each_leaf_node_possible_cpu() in force_qs_rnp() with > for_each_leaf_node_cpu() to save several checks. > > [Note we need to use "1UL << bit" instead of "1 << bit" to generate the > corresponding mask for a bit because @mask is unsigned long, this was > spotted by Colin Ian King <colin.king@canonical.com> and CoverityScan in > a previous version of this patch.]
Nit: This note can go now that we use leaf_node_cpu_bit(). ;)
Thanks, Mark.
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> > --- > kernel/rcu/tree.c | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 4e5b81c843de..1ef13e63bc95 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -3046,13 +3046,11 @@ static void force_qs_rnp(struct rcu_state *rsp, > continue; > } > } > - for_each_leaf_node_possible_cpu(rnp, cpu) { > - unsigned long bit = leaf_node_cpu_bit(rnp, cpu); > - if ((rnp->qsmask & bit) != 0) { > - if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj)) > - mask |= bit; > - } > - } > + > + for_each_leaf_node_cpu(rnp, rnp->qsmask, cpu) > + if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj)) > + mask |= leaf_node_cpu_bit(rnp, cpu); > + > if (mask != 0) { > /* Idle/offline CPUs, report (releases rnp->lock. */ > rcu_report_qs_rnp(mask, rsp, rnp, rnp->gpnum, flags); > -- > 2.10.2 >
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