diff options
Diffstat (limited to 'block/blk-throttle.c')
| -rw-r--r-- | block/blk-throttle.c | 80 |
1 files changed, 42 insertions, 38 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index dc6140fa3de0..2c4192e12efa 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -31,14 +31,6 @@ static struct workqueue_struct *kthrotld_workqueue; #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) -/* We measure latency for request size from <= 4k to >= 1M */ -#define LATENCY_BUCKET_SIZE 9 - -struct latency_bucket { - unsigned long total_latency; /* ns / 1024 */ - int samples; -}; - struct throtl_data { /* service tree for active throtl groups */ @@ -116,9 +108,6 @@ static unsigned int tg_iops_limit(struct throtl_grp *tg, int rw) return tg->iops[rw]; } -#define request_bucket_index(sectors) \ - clamp_t(int, order_base_2(sectors) - 3, 0, LATENCY_BUCKET_SIZE - 1) - /** * throtl_log - log debug message via blktrace * @sq: the service_queue being reported @@ -1595,6 +1584,22 @@ void blk_throtl_cancel_bios(struct gendisk *disk) spin_unlock_irq(&q->queue_lock); } +static bool tg_within_limit(struct throtl_grp *tg, struct bio *bio, bool rw) +{ + /* throtl is FIFO - if bios are already queued, should queue */ + if (tg->service_queue.nr_queued[rw]) + return false; + + return tg_may_dispatch(tg, bio, NULL); +} + +static void tg_dispatch_in_debt(struct throtl_grp *tg, struct bio *bio, bool rw) +{ + if (!bio_flagged(bio, BIO_BPS_THROTTLED)) + tg->carryover_bytes[rw] -= throtl_bio_data_size(bio); + tg->carryover_ios[rw]--; +} + bool __blk_throtl_bio(struct bio *bio) { struct request_queue *q = bdev_get_queue(bio->bi_bdev); @@ -1611,34 +1616,35 @@ bool __blk_throtl_bio(struct bio *bio) sq = &tg->service_queue; while (true) { - if (tg->last_low_overflow_time[rw] == 0) - tg->last_low_overflow_time[rw] = jiffies; - /* throtl is FIFO - if bios are already queued, should queue */ - if (sq->nr_queued[rw]) - break; - - /* if above limits, break to queue */ - if (!tg_may_dispatch(tg, bio, NULL)) { - tg->last_low_overflow_time[rw] = jiffies; + if (tg_within_limit(tg, bio, rw)) { + /* within limits, let's charge and dispatch directly */ + throtl_charge_bio(tg, bio); + + /* + * We need to trim slice even when bios are not being + * queued otherwise it might happen that a bio is not + * queued for a long time and slice keeps on extending + * and trim is not called for a long time. Now if limits + * are reduced suddenly we take into account all the IO + * dispatched so far at new low rate and * newly queued + * IO gets a really long dispatch time. + * + * So keep on trimming slice even if bio is not queued. + */ + throtl_trim_slice(tg, rw); + } else if (bio_issue_as_root_blkg(bio)) { + /* + * IOs which may cause priority inversions are + * dispatched directly, even if they're over limit. + * Debts are handled by carryover_bytes/ios while + * calculating wait time. + */ + tg_dispatch_in_debt(tg, bio, rw); + } else { + /* if above limits, break to queue */ break; } - /* within limits, let's charge and dispatch directly */ - throtl_charge_bio(tg, bio); - - /* - * We need to trim slice even when bios are not being queued - * otherwise it might happen that a bio is not queued for - * a long time and slice keeps on extending and trim is not - * called for a long time. Now if limits are reduced suddenly - * we take into account all the IO dispatched so far at new - * low rate and * newly queued IO gets a really long dispatch - * time. - * - * So keep on trimming slice even if bio is not queued. - */ - throtl_trim_slice(tg, rw); - /* * @bio passed through this layer without being throttled. * Climb up the ladder. If we're already at the top, it @@ -1661,8 +1667,6 @@ bool __blk_throtl_bio(struct bio *bio) tg->io_disp[rw], tg_iops_limit(tg, rw), sq->nr_queued[READ], sq->nr_queued[WRITE]); - tg->last_low_overflow_time[rw] = jiffies; - td->nr_queued[rw]++; throtl_add_bio_tg(bio, qn, tg); throttled = true; |