diff options
Diffstat (limited to 'block/blk-throttle.c')
| -rw-r--r-- | block/blk-throttle.c | 41 |
1 files changed, 26 insertions, 15 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 56ad4531b412..381b09bb562b 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -355,6 +355,12 @@ throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) tg->slice_end[rw], jiffies); } +static inline void throtl_set_slice_end(struct throtl_data *td, + struct throtl_grp *tg, bool rw, unsigned long jiffy_end) +{ + tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); +} + static inline void throtl_extend_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw, unsigned long jiffy_end) { @@ -391,6 +397,16 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) if (throtl_slice_used(td, tg, rw)) return; + /* + * A bio has been dispatched. Also adjust slice_end. It might happen + * that initially cgroup limit was very low resulting in high + * slice_end, but later limit was bumped up and bio was dispached + * sooner, then we need to reduce slice_end. A high bogus slice_end + * is bad because it does not allow new slice to start. + */ + + throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice); + time_elapsed = jiffies - tg->slice_start[rw]; nr_slices = time_elapsed / throtl_slice; @@ -645,7 +661,7 @@ static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg, { unsigned int nr_reads = 0, nr_writes = 0; unsigned int max_nr_reads = throtl_grp_quantum*3/4; - unsigned int max_nr_writes = throtl_grp_quantum - nr_reads; + unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads; struct bio *bio; /* Try to dispatch 75% READS and 25% WRITES */ @@ -709,26 +725,21 @@ static void throtl_process_limit_change(struct throtl_data *td) struct throtl_grp *tg; struct hlist_node *pos, *n; - /* - * Make sure atomic_inc() effects from - * throtl_update_blkio_group_read_bps(), group of functions are - * visible. - * Is this required or smp_mb__after_atomic_inc() was suffcient - * after the atomic_inc(). - */ - smp_rmb(); if (!atomic_read(&td->limits_changed)) return; throtl_log(td, "limit changed =%d", atomic_read(&td->limits_changed)); - hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) { - /* - * Do I need an smp_rmb() here to make sure tg->limits_changed - * update is visible. I am relying on smp_rmb() at the - * beginning of function and not putting a new one here. - */ + /* + * Make sure updates from throtl_update_blkio_group_read_bps() group + * of functions to tg->limits_changed are visible. We do not + * want update td->limits_changed to be visible but update to + * tg->limits_changed not being visible yet on this cpu. Hence + * the read barrier. + */ + smp_rmb(); + hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) { if (throtl_tg_on_rr(tg) && tg->limits_changed) { throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu" " riops=%u wiops=%u", tg->bps[READ], |
