On Fri 23-12-22 03:16:34, Kemeng Shi wrote: > Inject limit is updated or reset when time_is_before_eq_jiffies( > decrease_time_jif + several msecs) or think-time state changes. > decrease_time_jif is initialized to 0 and will be set to current jiffies > when inject limit is updated or reset. If the jiffies is slightly greater > than LONG_MAX, time_is_after_eq_jiffies(0) will keep for a long time, so as > time_is_after_eq_jiffies(decrease_time_jif + several msecs). If the > think-time state never chages, then the injection will not work as expected > for long time. > > To be more specific: > Function bfq_update_inject_limit maybe triggered when jiffies pasts > decrease_time_jif + msecs_to_jiffies(10) in bfq_add_request by setting > bfqd->wait_dispatch to true. > Function bfq_reset_inject_limit are called in two conditions: > 1. jiffies pasts bfqq->decrease_time_jif + msecs_to_jiffies(1000) in > function bfq_add_request. > 2. jiffies pasts bfqq->decrease_time_jif + msecs_to_jiffies(100) or > bfq think-time state change from short to long. > > Fix this by initializing bfqq->decrease_time_jif to current jiffies > to trigger service injection soon when service injection conditions > are met. > > Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> I agree that initializing jiffies timer to 0 is just a bad practice and current time is much saner choice. Feel free to add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza > --- > block/bfq-iosched.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c > index 5a6d9e8c329d..9441fc98961a 100644 > --- a/block/bfq-iosched.c > +++ b/block/bfq-iosched.c > @@ -5491,6 +5491,8 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, > > /* first request is almost certainly seeky */ > bfqq->seek_history = 1; > + > + bfqq->decrease_time_jif = jiffies; > } > > static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd, > -- > 2.30.0 > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
