Messages in this thread Patch in this message | | | From | paulmck@kernel ... | Subject | [PATCH tip/core/rcu 08/12] rcu: IPI all CPUs at GP start for strict GPs | Date | Wed, 12 Aug 2020 15:57:28 -0700 |
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From: "Paul E. McKenney" <paulmck@kernel.org>
Currently, each CPU discovers the beginning of a given grace period on its own time, which is again good for efficiency but bad for fast grace periods. This commit therefore uses on_each_cpu() to IPI each CPU after grace-period initialization in order to inform each CPU of the new grace period in a timely manner, but only in kernels build with CONFIG_RCU_STRICT_GRACE_PERIOD=y.
Reported-by Jann Horn <jannh@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> --- kernel/rcu/tree.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 4353a1a..a30d6f3 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1678,6 +1678,15 @@ static void rcu_gp_torture_wait(void) } /* + * Handler for on_each_cpu() to invoke the target CPU's RCU core + * processing. + */ +static void rcu_strict_gp_boundary(void *unused) +{ + invoke_rcu_core(); +} + +/* * Initialize a new grace period. Return false if no grace period required. */ static bool rcu_gp_init(void) @@ -1805,6 +1814,10 @@ static bool rcu_gp_init(void) WRITE_ONCE(rcu_state.gp_activity, jiffies); } + // If strict, make all CPUs aware of new grace period. + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) + on_each_cpu(rcu_strict_gp_boundary, NULL, 0); + return true; } -- 2.9.5
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