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Fri, 17 Dec 2021 22:03:24 -0800 (PST) MIME-Version: 1.0 References: <1639721264-12294-1-git-send-email-huangzhaoyang@gmail.com> In-Reply-To: <1639721264-12294-1-git-send-email-huangzhaoyang@gmail.com> From: Zhaoyang Huang Date: Sat, 18 Dec 2021 14:03:04 +0800 Message-ID: Subject: Re: [PATCH] psi: fix possible trigger missing in the window To: Johannes Weiner , Zhaoyang Huang , "open list:MEMORY MANAGEMENT" , LKML , Suren Baghdasaryan Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org loop Suren On Fri, Dec 17, 2021 at 2:08 PM Huangzhaoyang wrote: > > From: Zhaoyang Huang > > There could be missing wake up if the rest of the window remain the > same stall states as the polling_total updates for every polling_min_period. > > Signed-off-by: Zhaoyang Huang > --- > include/linux/psi_types.h | 2 ++ > kernel/sched/psi.c | 30 ++++++++++++++++++------------ > 2 files changed, 20 insertions(+), 12 deletions(-) > > diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h > index 0a23300..9533d2e 100644 > --- a/include/linux/psi_types.h > +++ b/include/linux/psi_types.h > @@ -132,6 +132,8 @@ struct psi_trigger { > > /* Refcounting to prevent premature destruction */ > struct kref refcount; > + > + bool new_stall; > }; > > struct psi_group { > diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c > index 1652f2b..402718c 100644 > --- a/kernel/sched/psi.c > +++ b/kernel/sched/psi.c > @@ -458,9 +458,12 @@ static void psi_avgs_work(struct work_struct *work) > static void window_reset(struct psi_window *win, u64 now, u64 value, > u64 prev_growth) > { > + struct psi_trigger *t = container_of(win, struct psi_trigger, win); > + > win->start_time = now; > win->start_value = value; > win->prev_growth = prev_growth; > + t->new_stall = false; > } > > /* > @@ -515,7 +518,6 @@ static void init_triggers(struct psi_group *group, u64 now) > static u64 update_triggers(struct psi_group *group, u64 now) > { > struct psi_trigger *t; > - bool new_stall = false; > u64 *total = group->total[PSI_POLL]; > > /* > @@ -523,19 +525,26 @@ static u64 update_triggers(struct psi_group *group, u64 now) > * watchers know when their specified thresholds are exceeded. > */ > list_for_each_entry(t, &group->triggers, node) { > - u64 growth; > - > /* Check for stall activity */ > if (group->polling_total[t->state] == total[t->state]) > continue; > > /* > - * Multiple triggers might be looking at the same state, > - * remember to update group->polling_total[] once we've > - * been through all of them. Also remember to extend the > - * polling time if we see new stall activity. > + * update the trigger if there is new stall which will be > + * reset when run out of the window > */ > - new_stall = true; > + t->new_stall = true; > + > + memcpy(&group->polling_total[t->state], &total[t->state], > + sizeof(group->polling_total[t->state])); > + } > + > + list_for_each_entry(t, &group->triggers, node) { > + u64 growth; > + > + /* check if new stall happened during this window*/ > + if (!t->new_stall) > + continue; > > /* Calculate growth since last update */ > growth = window_update(&t->win, now, total[t->state]); > @@ -552,10 +561,6 @@ static u64 update_triggers(struct psi_group *group, u64 now) > t->last_event_time = now; > } > > - if (new_stall) > - memcpy(group->polling_total, total, > - sizeof(group->polling_total)); > - > return now + group->poll_min_period; > } > > @@ -1152,6 +1157,7 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, > t->last_event_time = 0; > init_waitqueue_head(&t->event_wait); > kref_init(&t->refcount); > + t->new_stall = false; > > mutex_lock(&group->trigger_lock); > > -- > 1.9.1 >