On Tue, Nov 27 2018 at 7:42pm -0500, Mikulas Patocka <[email protected]> wrote:
> Now when part_round_stats is gone, we can switch to per-cpu in-flight > counters. > > We use the local-atomic type local_t, so that if part_inc_in_flight or > part_dec_in_flight is reentrantly called from an interrupt, the value will > be correct. > > The other counters could be corrupted due to reentrant interrupt, but the > corruption only results in slight counter skew - the in_flight counter > must be exact, so it needs local_t. > > Signed-off-by: Mikulas Patocka <[email protected]> > > --- > block/bio.c | 4 ++-- > block/blk-core.c | 4 ++-- > block/blk-merge.c | 2 +- > block/genhd.c | 47 +++++++++++++++++++++++++++++++++++------------ > drivers/md/dm.c | 4 +--- > include/linux/genhd.h | 7 ++++--- > 6 files changed, 45 insertions(+), 23 deletions(-) > > Index: linux-block/block/genhd.c > =================================================================== > --- linux-block.orig/block/genhd.c 2018-11-28 00:09:59.000000000 +0100 > +++ linux-block/block/genhd.c 2018-11-28 00:09:59.000000000 +0100 > @@ -45,53 +45,76 @@ static void disk_add_events(struct gendi > static void disk_del_events(struct gendisk *disk); > static void disk_release_events(struct gendisk *disk); > > -void part_inc_in_flight(struct request_queue *q, struct hd_struct *part, int > rw) > +void part_inc_in_flight(struct request_queue *q, int cpu, struct hd_struct > *part, int rw) > { > if (queue_is_mq(q)) > return; > > - atomic_inc(&part->in_flight[rw]); > + local_inc(per_cpu_ptr(part->dkstats, cpu)->in_flight); > if (part->partno) > - atomic_inc(&part_to_disk(part)->part0.in_flight[rw]); > + local_inc(per_cpu_ptr(part_to_disk(part)->part0.dkstats, > cpu)->in_flight); > } > > -void part_dec_in_flight(struct request_queue *q, struct hd_struct *part, int > rw) > +void part_dec_in_flight(struct request_queue *q, int cpu, struct hd_struct > *part, int rw) > { > if (queue_is_mq(q)) > return; > > - atomic_dec(&part->in_flight[rw]); > + local_dec(per_cpu_ptr(part->dkstats, cpu)->in_flight); > if (part->partno) > - atomic_dec(&part_to_disk(part)->part0.in_flight[rw]); > + local_dec(per_cpu_ptr(part_to_disk(part)->part0.dkstats, > cpu)->in_flight); > } The above is wrong, needs this incremental fix: diff --git a/block/genhd.c b/block/genhd.c index 2ed431098953..3397288a2926 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -50,9 +50,9 @@ void part_inc_in_flight(struct request_queue *q, int cpu, struct hd_struct *part if (queue_is_mq(q)) return; - local_inc(per_cpu_ptr(part->dkstats, cpu)->in_flight); + local_inc(&per_cpu_ptr(part->dkstats, cpu)->in_flight[rw]); if (part->partno) - local_inc(per_cpu_ptr(part_to_disk(part)->part0.dkstats, cpu)->in_flight); + local_inc(&per_cpu_ptr(part_to_disk(part)->part0.dkstats, cpu)->in_flight[rw]); } void part_dec_in_flight(struct request_queue *q, int cpu, struct hd_struct *part, int rw) @@ -60,9 +60,9 @@ void part_dec_in_flight(struct request_queue *q, int cpu, struct hd_struct *part if (queue_is_mq(q)) return; - local_dec(per_cpu_ptr(part->dkstats, cpu)->in_flight); + local_dec(&per_cpu_ptr(part->dkstats, cpu)->in_flight[rw]); if (part->partno) - local_dec(per_cpu_ptr(part_to_disk(part)->part0.dkstats, cpu)->in_flight); + local_dec(&per_cpu_ptr(part_to_disk(part)->part0.dkstats, cpu)->in_flight[rw]); } unsigned int part_in_flight(struct request_queue *q, struct hd_struct *part) -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
