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| author | Paolo Valente <paolo.valente@linaro.org> | 2019-03-12 09:59:31 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-04-01 08:15:40 -0600 |
| commit | 7074f076ff153021f408229b0ce63063dde9a400 (patch) | |
| tree | 692007553290b883af2a141ca72890621089fbf8 /block | |
| parent | 8cacc5ab3eacf5284bc9b0d7d5b85b748a338104 (diff) | |
| download | linux-7074f076ff153021f408229b0ce63063dde9a400.tar.bz2 | |
block, bfq: do not tag totally seeky queues as soft rt
Sync random I/O is likely to be confused with soft real-time I/O,
because it is characterized by limited throughput and apparently
isochronous arrival pattern. To avoid false positives, this commits
prevents bfq_queues containing only random (seeky) I/O from being
tagged as soft real-time.
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/bfq-iosched.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index b957e9db87d8..7044da0b1c52 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -242,6 +242,14 @@ static struct kmem_cache *bfq_pool; blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT)) #define BFQQ_CLOSE_THR (sector_t)(8 * 1024) #define BFQQ_SEEKY(bfqq) (hweight32(bfqq->seek_history) > 19) +/* + * Sync random I/O is likely to be confused with soft real-time I/O, + * because it is characterized by limited throughput and apparently + * isochronous arrival pattern. To avoid false positives, queues + * containing only random (seeky) I/O are prevented from being tagged + * as soft real-time. + */ +#define BFQQ_TOTALLY_SEEKY(bfqq) (bfqq->seek_history & -1) /* Min number of samples required to perform peak-rate update */ #define BFQ_RATE_MIN_SAMPLES 32 @@ -1622,6 +1630,7 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd, */ in_burst = bfq_bfqq_in_large_burst(bfqq); soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 && + !BFQQ_TOTALLY_SEEKY(bfqq) && !in_burst && time_is_before_jiffies(bfqq->soft_rt_next_start) && bfqq->dispatched == 0; @@ -4816,6 +4825,11 @@ bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq, { bfqq->seek_history <<= 1; bfqq->seek_history |= BFQ_RQ_SEEKY(bfqd, bfqq->last_request_pos, rq); + + if (bfqq->wr_coeff > 1 && + bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time && + BFQQ_TOTALLY_SEEKY(bfqq)) + bfq_bfqq_end_wr(bfqq); } static void bfq_update_has_short_ttime(struct bfq_data *bfqd, |