| Message ID | 20211221032135.878550-3-yukuai3@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block, bfq: minor cleanup and fix | expand |
On Tue 21-12-21 11:21:33, Yu Kuai wrote: > Moving bfqq to it's parent bfqg is pointless. > > Signed-off-by: Yu Kuai <yukuai3@huawei.com> Did you notice that this is happening often enough that the check is worth it? Where do we do this? Honza > --- > block/bfq-cgroup.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c > index 24a5c5329bcd..0f62546a72d4 100644 > --- a/block/bfq-cgroup.c > +++ b/block/bfq-cgroup.c > @@ -645,6 +645,11 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, > struct bfq_group *bfqg) > { > struct bfq_entity *entity = &bfqq->entity; > + struct bfq_group *old_parent = bfq_group(bfqq); > + > + /* No point to move bfqq to the same group */ > + if (old_parent == bfqg) > + return; > > /* > * Get extra reference to prevent bfqq from being freed in > @@ -666,7 +671,7 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, > bfq_deactivate_bfqq(bfqd, bfqq, false, false); > else if (entity->on_st_or_in_serv) > bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); > - bfqg_and_blkg_put(bfqq_group(bfqq)); > + bfqg_and_blkg_put(old_parent); > > if (entity->parent && > entity->parent->last_bfqq_created == bfqq) > -- > 2.31.1 >
在 2021/12/21 18:16, Jan Kara 写道: > On Tue 21-12-21 11:21:33, Yu Kuai wrote: >> Moving bfqq to it's parent bfqg is pointless. >> >> Signed-off-by: Yu Kuai <yukuai3@huawei.com> > > Did you notice that this is happening often enough that the check is worth > it? Where do we do this? > I noticed that this will happend when root group is offlined: bfq_pd_offline bfq_put_async_queues __bfq_put_async_bfqq bfq_bfqq_move I'm not sure if there are other situations. I think bfq_bfqq_move() is not happening often itself, thus the checking won't affect performance. Thanks, Kuai > Honza > >> --- >> block/bfq-cgroup.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c >> index 24a5c5329bcd..0f62546a72d4 100644 >> --- a/block/bfq-cgroup.c >> +++ b/block/bfq-cgroup.c >> @@ -645,6 +645,11 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, >> struct bfq_group *bfqg) >> { >> struct bfq_entity *entity = &bfqq->entity; >> + struct bfq_group *old_parent = bfq_group(bfqq); >> + >> + /* No point to move bfqq to the same group */ >> + if (old_parent == bfqg) >> + return; >> >> /* >> * Get extra reference to prevent bfqq from being freed in >> @@ -666,7 +671,7 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, >> bfq_deactivate_bfqq(bfqd, bfqq, false, false); >> else if (entity->on_st_or_in_serv) >> bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); >> - bfqg_and_blkg_put(bfqq_group(bfqq)); >> + bfqg_and_blkg_put(old_parent); >> >> if (entity->parent && >> entity->parent->last_bfqq_created == bfqq) >> -- >> 2.31.1 >>
On Tue 21-12-21 19:08:44, yukuai (C) wrote: > 在 2021/12/21 18:16, Jan Kara 写道: > > On Tue 21-12-21 11:21:33, Yu Kuai wrote: > > > Moving bfqq to it's parent bfqg is pointless. > > > > > > Signed-off-by: Yu Kuai <yukuai3@huawei.com> > > > > Did you notice that this is happening often enough that the check is worth > > it? Where do we do this? > > > > I noticed that this will happend when root group is offlined: > > bfq_pd_offline > bfq_put_async_queues > __bfq_put_async_bfqq > bfq_bfqq_move > > I'm not sure if there are other situations. I think bfq_bfqq_move() > is not happening often itself, thus the checking won't affect > performance. Yeah, OK, I was just wondering. I guess there's no harm in doing this check. Maybe add a comment that this can sometimes happen when dealing with the root cgroup. And then feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 24a5c5329bcd..0f62546a72d4 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -645,6 +645,11 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, struct bfq_group *bfqg) { struct bfq_entity *entity = &bfqq->entity; + struct bfq_group *old_parent = bfq_group(bfqq); + + /* No point to move bfqq to the same group */ + if (old_parent == bfqg) + return; /* * Get extra reference to prevent bfqq from being freed in @@ -666,7 +671,7 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, bfq_deactivate_bfqq(bfqd, bfqq, false, false); else if (entity->on_st_or_in_serv) bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); - bfqg_and_blkg_put(bfqq_group(bfqq)); + bfqg_and_blkg_put(old_parent); if (entity->parent && entity->parent->last_bfqq_created == bfqq)
Moving bfqq to it's parent bfqg is pointless. Signed-off-by: Yu Kuai <yukuai3@huawei.com> --- block/bfq-cgroup.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)