From: Paolo Valente <paolo.valente@linaro.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
ulf.hansson@linaro.org, linus.walleij@linaro.org,
broonie@kernel.org, bfq-iosched@googlegroups.com,
oleksandr@natalenko.name, fra.fra.800@gmail.com,
alessio.masola@gmail.com, holger@applied-asynchrony.com,
Paolo Valente <paolo.valente@linaro.org>
Subject: [PATCH BUGFIX IMPROVEMENT V3 5/9] block, bfq: do not tag totally seeky queues as soft rt
Date: Tue, 12 Mar 2019 09:59:31 +0100 [thread overview]
Message-ID: <20190312085935.11340-6-paolo.valente@linaro.org> (raw)
In-Reply-To: <20190312085935.11340-1-paolo.valente@linaro.org>
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>
---
block/bfq-iosched.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index b96be3764b8a..d34b80e5c47d 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,
--
2.20.1
next prev parent reply other threads:[~2019-03-12 9:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-12 8:59 [PATCH BUGFIX IMPROVEMENT V3 0/9] lock, bfq: fix bugs, reduce exec time and boost performance Paolo Valente
2019-03-12 8:59 ` [PATCH BUGFIX IMPROVEMENT V3 1/9] block, bfq: increase idling for weight-raised queues Paolo Valente
2019-03-12 8:59 ` [PATCH BUGFIX IMPROVEMENT V3 2/9] block, bfq: do not idle for lowest-weight queues Paolo Valente
2019-03-12 8:59 ` [PATCH BUGFIX IMPROVEMENT V3 3/9] block, bfq: tune service injection basing on request service times Paolo Valente
2019-03-12 8:59 ` [PATCH BUGFIX IMPROVEMENT V3 4/9] block, bfq: do not merge queues on flash storage with queueing Paolo Valente
2019-03-12 8:59 ` Paolo Valente [this message]
2019-03-12 8:59 ` [PATCH BUGFIX IMPROVEMENT V3 6/9] block, bfq: always protect newly-created queues from existing active queues Paolo Valente
2019-03-12 8:59 ` [PATCH BUGFIX IMPROVEMENT V3 7/9] block, bfq: print SHARED instead of pid for shared queues in logs Paolo Valente
2019-03-12 8:59 ` [PATCH BUGFIX IMPROVEMENT V3 8/9] block, bfq: save & resume weight on a queue merge/split Paolo Valente
2019-03-12 8:59 ` [PATCH BUGFIX IMPROVEMENT V3 9/9] doc, block, bfq: add information on bfq execution time Paolo Valente
2019-03-26 11:53 ` [PATCH BUGFIX IMPROVEMENT V3 0/9] lock, bfq: fix bugs, reduce exec time and boost performance Paolo Valente
2019-03-26 14:13 ` Jens Axboe
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