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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: PH0PR11MB5880.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: a72e7d2f-9ce0-4535-fe7d-08da01798117 X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Mar 2022 03:04:19.4056 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: sMb9Ko4FoRHeH7KrfQ5bWWJtWitnGgyBNP+1GZdz3vs1MKkMnSPK+YhU8mDSiLZsrIOH1MdXPvzhPY/HfYGF0A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR11MB4341 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Mon, Mar 07, 2022 at 02:03:17AM +0000, Zhang, Qiang1 wrote: > > On 3/4/2022 2:56 PM, Zqiang wrote: > > > When RCU_BOOST is enabled, the boost kthreads will boosting=20 > > > readers who are blocking a given grace period, if the current=20 > > > reader tasks have a higher priority than boost kthreads(the boost=20 > > > kthreads priority not always 1, if the kthread_prio is set),=20 > > > boosting is useless, skip current task and select next task to=20 > > > boosting, reduce the time for a given grace period. > > >=20 > > > Signed-off-by: Zqiang >=20 > Adding to CC to get more eyes on this. I am not necessarily opposed=20 > to it, but I don't do that much RT work myself these days. >=20 > Thanx, Paul >=20 > > > --- > > > kernel/rcu/tree_plugin.h | 10 +++++++++- > > > 1 file changed, 9 insertions(+), 1 deletion(-) > > >=20 > > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h=20 > > > index c3d212bc5338..d35b6da66bbd 100644 > > > --- a/kernel/rcu/tree_plugin.h > > > +++ b/kernel/rcu/tree_plugin.h > > > @@ -12,6 +12,7 @@ > > > */ > > > =20 > > > #include "../locking/rtmutex_common.h" > > > +#include > > > =20 > > > static bool rcu_rdp_is_offloaded(struct rcu_data *rdp) > > > { > > > @@ -1065,13 +1066,20 @@ static int rcu_boost(struct rcu_node *rnp) > > > * section. > > > */ > > > t =3D container_of(tb, struct task_struct, rcu_node_entry); > > > + if (!rnp->exp_tasks && (dl_task(t) || t->prio <=3D current->prio)) = { > > > + tb =3D rcu_next_node_entry(t, rnp); > > > + WRITE_ONCE(rnp->boost_tasks, tb); > > > + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); > > > + goto end; > > > + } > > > + >>>>Why do you bypass the expedited grace period and boost any tasks anyway= ? >>>>Same way the expedited gp can be blocked by higher prior tasks SCHED_DE= ADLINE or SCHED_FIFO. Thanks advice, it really ignores expedited grace period, may be should generate 'boost_exp_tasks' pointer to point 'rnp->exp_tasks', do the= same thing as normal grace period. Thanks Zqiang >>>> >>>>Thanks! >>>> >>>>-- >>>>Vlad Rezki