On Mon, Oct 07, 2019 at 08:33:53PM -0700, Paul E. McKenney wrote: [...]
kernel/rcu/tree_exp.h | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index af7e7b9c86af..fb51752ac9a6 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -372,12 +372,10 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp) raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
/* IPI the remaining CPUs for expedited quiescent state. */
- for_each_leaf_node_cpu_mask(rnp, cpu, rnp->expmask) {
- for_each_leaf_node_cpu_mask(rnp, cpu, mask_ofl_ipi) { unsigned long mask = leaf_node_cpu_bit(rnp, cpu); struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
if (!(mask_ofl_ipi & mask))continue;retry_ipi: if (rcu_dynticks_in_eqs_since(rdp, rdp->exp_dynticks_snap)) { mask_ofl_test |= mask;
This part I have already on -rcu branch "dev".
@@ -389,10 +387,10 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp) } ret = smp_call_function_single(cpu, rcu_exp_handler, NULL, 0); put_cpu();
if (!ret) {mask_ofl_ipi &= ~mask;
/* the CPU responses the IPI, and it will report QS itself */if (!ret) continue;
}
- /* Failed, raced with CPU hotplug operation. */ raw_spin_lock_irqsave_rcu_node(rnp, flags); if ((rnp->qsmaskinitnext & mask) &&
@@ -403,13 +401,12 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp) schedule_timeout_uninterruptible(1); goto retry_ipi; }
/* CPU really is offline, so we can ignore it. */if (!(rnp->expmask & mask))mask_ofl_ipi &= ~mask;
/* CPU really is offline, and we need its QS. */if (rnp->expmask & mask)mask_ofl_test |= mask;
- mask_ofl_test |= mask_ofl_ipi; if (mask_ofl_test) rcu_report_exp_cpu_mult(rnp, mask_ofl_test, false);
}
Would you be willing to port this optimization on top of current -rcu branch "dev" with an suitably modified commit message?
Sure, will do ;-)
Regards, Boqun
Thanx, Paul