[RFC 0/5] rcu: Introduce leaf_node_for_each_mask_possible_cpu() and its friend

From	Boqun Feng <boqun.feng@gmail.com>
Newsgroups	linux.kernel
Subject	[RFC 0/5] rcu: Introduce leaf_node_for_each_mask_possible_cpu() and its friend
Date	2016-12-09 09:50 +0100
Message-ID	<sMp2p-12O-13@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hi Paul,

While reading the discussion at:

https://marc.info/?l=linux-kernel&m=148044253400769

I figured we might use this fact to save some extra checks in RCU core code,
currently we iterate over all the possible CPUs on a leaf node, check whether
they were masked in a certain mask and do something. However, given the fact
that the masks on a leaf node should always be sparse than the corresponding
part of cpu_possible_mask, we'd better iterate over all bits in a mask and
check whether the corresponding CPU is possible or not.

So I made this RFC, I did a simple build/boot/rcutorture test on my box with
SMP=4, nothing bad happens. Currently I'm waiting for the 0day and trying to
test this one a bigger system, in the meanwhile, looking forwards to any
comment and suggestion.

So thoughts?

Regards,
Boqun

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[RFC 0/5] rcu: Introduce leaf_node_for_each_mask_possible_cpu() and its friend Boqun Feng <boqun.feng@gmail.com> - 2016-12-09 09:50 +0100
  [RFC 5/5] rcu: Use leaf_node_for_each_mask_*() for leaf node online CPU iteration Boqun Feng <boqun.feng@gmail.com> - 2016-12-09 10:00 +0100
  Re: [RFC 0/5] rcu: Introduce leaf_node_for_each_mask_possible_cpu()  and its friend "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-10 00:50 +0100
    Re: [RFC 0/5] rcu: Introduce leaf_node_for_each_mask_possible_cpu()  and its friend Boqun Feng <boqun.feng@gmail.com> - 2016-12-10 01:50 +0100
      Re: [RFC 0/5] rcu: Introduce leaf_node_for_each_mask_possible_cpu()  and its friend "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-10 05:30 +0100
        Re: [RFC 0/5] rcu: Introduce leaf_node_for_each_mask_possible_cpu()  and its friend Boqun Feng <boqun.feng@gmail.com> - 2016-12-10 14:40 +0100
          Re: [RFC 0/5] rcu: Introduce leaf_node_for_each_mask_possible_cpu()  and its friend "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-10 18:40 +0100
            Re: [RFC 0/5] rcu: Introduce leaf_node_for_each_mask_possible_cpu()  and its friend Boqun Feng <boqun.feng@gmail.com> - 2016-12-11 01:10 +0100

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