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| author | Paolo Valente <paolo.valente@linaro.org> | 2021-03-04 18:46:24 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-03-25 10:50:07 -0600 |
| commit | 8ef3fc3a043cd4b3dfdb260f02be5f65cc31445d (patch) | |
| tree | dbfe2b6b5847271e4a7c177bbd602661d9617fe9 /block/bfq-iosched.c | |
| parent | 7cc4ffc55564df4349050bcbf46fbdf3f35aef52 (diff) | |
| download | lwn-8ef3fc3a043cd4b3dfdb260f02be5f65cc31445d.tar.gz lwn-8ef3fc3a043cd4b3dfdb260f02be5f65cc31445d.zip | |
block, bfq: make shared queues inherit wakers
Consider a bfq_queue bfqq that is about to be merged with another
bfq_queue new_bfqq. The processes associated with bfqq are cooperators
of the processes associated with new_bfqq. So, if bfqq has a waker,
then it is reasonable (and beneficial for throughput) to assume that
all these processes will be happy to let bfqq's waker freely inject
I/O when they have no I/O. So this commit makes new_bfqq inherit
bfqq's waker.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Link: https://lore.kernel.org/r/20210304174627.161-4-paolo.valente@linaro.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bfq-iosched.c')
| -rw-r--r-- | block/bfq-iosched.c | 42 |
1 files changed, 39 insertions, 3 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index df840f37889d..b00dcc46bac7 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2823,6 +2823,29 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, bfq_clear_bfqq_IO_bound(bfqq); /* + * The processes associated with bfqq are cooperators of the + * processes associated with new_bfqq. So, if bfqq has a + * waker, then assume that all these processes will be happy + * to let bfqq's waker freely inject I/O when they have no + * I/O. + */ + if (bfqq->waker_bfqq && !new_bfqq->waker_bfqq && + bfqq->waker_bfqq != new_bfqq) { + new_bfqq->waker_bfqq = bfqq->waker_bfqq; + new_bfqq->tentative_waker_bfqq = NULL; + + /* + * If the waker queue disappears, then + * new_bfqq->waker_bfqq must be reset. So insert + * new_bfqq into the woken_list of the waker. See + * bfq_check_waker for details. + */ + hlist_add_head(&new_bfqq->woken_list_node, + &new_bfqq->waker_bfqq->woken_list); + + } + + /* * If bfqq is weight-raised, then let new_bfqq inherit * weight-raising. To reduce false positives, neglect the case * where bfqq has just been created, but has not yet made it @@ -6310,7 +6333,7 @@ static struct bfq_queue *bfq_init_rq(struct request *rq) if (likely(!new_queue)) { /* If the queue was seeky for too long, break it apart. */ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) { - bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq"); + struct bfq_queue *old_bfqq = bfqq; /* Update bic before losing reference to bfqq */ if (bfq_bfqq_in_large_burst(bfqq)) @@ -6319,11 +6342,24 @@ static struct bfq_queue *bfq_init_rq(struct request *rq) bfqq = bfq_split_bfqq(bic, bfqq); split = true; - if (!bfqq) + if (!bfqq) { bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, true, is_sync, NULL); - else + bfqq->waker_bfqq = old_bfqq->waker_bfqq; + bfqq->tentative_waker_bfqq = NULL; + + /* + * If the waker queue disappears, then + * new_bfqq->waker_bfqq must be + * reset. So insert new_bfqq into the + * woken_list of the waker. See + * bfq_check_waker for details. + */ + if (bfqq->waker_bfqq) + hlist_add_head(&bfqq->woken_list_node, + &bfqq->waker_bfqq->woken_list); + } else bfqq_already_existing = true; } } |