diff options
| -rw-r--r-- | block/blk-throttle.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 8d149aff9fd0..a52f0d6b40ad 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -599,14 +599,23 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) * 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(tg, rw, jiffies + tg->td->throtl_slice); time_elapsed = rounddown(jiffies - tg->slice_start[rw], tg->td->throtl_slice); - if (!time_elapsed) + /* Don't trim slice until at least 2 slices are used */ + if (time_elapsed < tg->td->throtl_slice * 2) return; + /* + * The bio submission time may be a few jiffies more than the expected + * waiting time, due to 'extra_bytes' can't be divided in + * tg_within_bps_limit(), and also due to timer wakeup delay. In this + * case, adjust slice_start will discard the extra wait time, causing + * lower rate than expected. Therefore, other than the above rounddown, + * one extra slice is preserved for deviation. + */ + time_elapsed -= tg->td->throtl_slice; bytes_trim = calculate_bytes_allowed(tg_bps_limit(tg, rw), time_elapsed) + tg->carryover_bytes[rw]; |