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| author | Alison Chaiken <achaiken@aurora.tech> | 2022-01-12 00:32:52 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-02-02 02:19:25 +0100 |
| commit | c8b16a65267e35ecc5621dbc81cbe7e5b0992fce (patch) | |
| tree | 99ff340a284841b875aa4ca4b2d146ce97ebf181 /kernel/rcu | |
| parent | rcu: Make priority of grace-period thread consistent (diff) | |
| download | linux-c8b16a65267e35ecc5621dbc81cbe7e5b0992fce.tar.xz linux-c8b16a65267e35ecc5621dbc81cbe7e5b0992fce.zip | |
rcu: Elevate priority of offloaded callback threads
When CONFIG_PREEMPT_RT=y, the rcutree.kthread_prio command-line
parameter signals initialization code to boost the priority of rcuc
callbacks to the designated value. With the additional
CONFIG_RCU_NOCB_CPU=y configuration and an additional rcu_nocbs
command-line parameter, the callbacks on the listed cores are
offloaded to new rcuop kthreads that are not pinned to the cores whose
post-grace-period work is performed. While the rcuop kthreads perform
the same function as the rcuc kthreads they offload, the kthread_prio
parameter only boosts the priority of the rcuc kthreads. Fix this
inconsistency by elevating rcuop kthreads to the same priority as the rcuc
kthreads.
Signed-off-by: Alison Chaiken <achaiken@aurora.tech>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 2 | ||||
| -rw-r--r-- | kernel/rcu/tree_nocb.h | 3 |
2 files changed, 4 insertions, 1 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 5bf0312f6676..9e4c5b281f00 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -153,7 +153,7 @@ static void sync_sched_exp_online_cleanup(int cpu); static void check_cb_ovld_locked(struct rcu_data *rdp, struct rcu_node *rnp); static bool rcu_rdp_is_offloaded(struct rcu_data *rdp); -/* rcuc/rcub kthread realtime priority */ +/* rcuc/rcub/rcuop kthread realtime priority */ static int kthread_prio = IS_ENABLED(CONFIG_RCU_BOOST) ? 1 : 0; module_param(kthread_prio, int, 0444); diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index ea889cbfc3b9..547c41437c76 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -1270,6 +1270,9 @@ static void rcu_spawn_cpu_nocb_kthread(int cpu) "rcuo%c/%d", rcu_state.abbr, cpu); if (WARN_ONCE(IS_ERR(t), "%s: Could not start rcuo CB kthread, OOM is now expected behavior\n", __func__)) return; + + if (kthread_prio) + sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); WRITE_ONCE(rdp->nocb_cb_kthread, t); WRITE_ONCE(rdp->nocb_gp_kthread, rdp_gp->nocb_gp_kthread); } |