[ Upstream commit 73aeab373557fa6ee4ae0b742c6211ccd9859280 ]
Original state:
Process 1 Process 2 Process 3 Process 4
(BIC1) (BIC2) (BIC3) (BIC4)
Λ | | |
\--------------\ \-------------\ \-------------\|
V V V
bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
ref 0 1 2 4
After commit 0e456dba86c7 ("block, bfq: choose the last bfqq from merge
chain in bfq_setup_cooperator()"), if P1 issues a new IO:
Without the patch:
Process 1 Process 2 Process 3 Process 4
(BIC1) (BIC2) (BIC3) (BIC4)
Λ | | |
\------------------------------\ \-------------\|
V V
bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
ref 0 0 2 4
bfqq3 will be used to handle IO from P1, this is not expected, IO
should be redirected to bfqq4;
With the patch:
-------------------------------------------
| |
Process 1 Process 2 Process 3 | Process 4
(BIC1) (BIC2) (BIC3) | (BIC4)
| | | |
\-------------\ \-------------\|
V V
bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
ref 0 0 2 4
IO is redirected to bfqq4, however, procress reference of bfqq3 is still
2, while there is only P2 using it.
Fix the problem by calling bfq_merge_bfqqs() for each bfqq in the merge
chain. Also change bfqq_merge_bfqqs() to return new_bfqq to simplify
code.
Fixes: 0e456dba86c7 ("block, bfq: choose the last bfqq from merge chain in bfq_setup_cooperator()")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240909134154.954924-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 42c306ed723321af4003b2a41bb73728cab54f85 ]
Consider the following scenario:
Process 1 Process 2 Process 3 Process 4
(BIC1) (BIC2) (BIC3) (BIC4)
Λ | | |
\-------------\ \-------------\ \--------------\|
V V V
bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
ref 0 1 2 4
If Process 1 issue a new IO and bfqq2 is found, and then bfq_init_rq()
decide to spilt bfqq2 by bfq_split_bfqq(). Howerver, procress reference
of bfqq2 is 1 and bfq_split_bfqq() just clear the coop flag, which will
break the merge chain.
Expected result: caller will allocate a new bfqq for BIC1
Process 1 Process 2 Process 3 Process 4
(BIC1) (BIC2) (BIC3) (BIC4)
| | |
\-------------\ \--------------\|
V V
bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
ref 0 0 1 3
Since the condition is only used for the last bfqq4 when the previous
bfqq2 and bfqq3 are already splited. Fix the problem by checking if
bfqq is the last one in the merge chain as well.
Fixes: 36eca8948323 ("block, bfq: add Early Queue Merge (EQM)")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240902130329.3787024-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 0e456dba86c7f9a19792204a044835f1ca2c8dbb ]
Consider the following merge chain:
Process 1 Process 2 Process 3 Process 4
(BIC1) (BIC2) (BIC3) (BIC4)
Λ | | |
\--------------\ \-------------\ \-------------\|
V V V
bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
IO from Process 1 will get bfqf2 from BIC1 first, then
bfq_setup_cooperator() will found bfqq2 already merged to bfqq3 and then
handle this IO from bfqq3. However, the merge chain can be much deeper
and bfqq3 can be merged to other bfqq as well.
Fix this problem by iterating to the last bfqq in
bfq_setup_cooperator().
Fixes: 36eca8948323 ("block, bfq: add Early Queue Merge (EQM)")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240902130329.3787024-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
The value of the I/O plugging (idling) timeout is used also as the
think-time threshold to decide whether a process has a short think
time. In this respect, a good value of this timeout for rotational
drives is un the order of several ms. Yet, this is often too long a
time interval to be effective as a think-time threshold. This commit
mitigates this problem (by a lot, according to tests), by halving the
threshold.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit b5f74ecacc3139ef873e69acc3aba28083ecc416)
(cherry picked from commit b1511c438e8a5668e6be04ad9107d6695332756c)
(cherry picked from commit 389992d9dc78340676248d0f01c7569b3db950ed)
(cherry picked from commit 49919eface6f4391cda0e77bcaad3e2786cbbab3)
(cherry picked from commit 87b015de51122ea9b5d9e56b846ae945db8444f0)
(cherry picked from commit 6ada34cdc94c89e97926a2d001412ecc027e1392)
(cherry picked from commit 2782bcc2919dd2a0a1d461d36c22338e67bc6327)
Tests on slower machines showed current window to be way too
small. This commit increases it.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit ab1fb47e33dc7754a7593181ffe0742c7105ea9a)
(cherry picked from commit 0d1663f1922c5f6fb3a4b3cc5a3a861c765a3704)
(cherry picked from commit 85d9e1637a38d0cfdeba4e3847f1797dcd18da5d)
(cherry picked from commit 6bd707bb9a60e2bf0e680a271208f6c82a331571)
(cherry picked from commit 43755e08d048ccd6f3b2a3bbd34bea4a71c5bc12)
(cherry picked from commit b1a8cce9e99277ce53da20ab603473ad6c3e95d1)
(cherry picked from commit 74d27133a3261a296ddd98e9ff09d89bfab797bb)
BFQ heuristics try to detect interactive I/O, and raise the weight of
the queues containing such an I/O. Yet, if also the user changes the
weight of a queue (i.e., the user changes the ioprio of the process
associated with that queue), then it is most likely better to prevent
BFQ heuristics from silently changing the same weight.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 91b896f65d32610d6d58af02170b15f8d37a7702)
(cherry picked from commit cbbd2f045e60073978fe1b721c0953cd8762ecbb)
(cherry picked from commit 88b650c71f7d0d30ac2fa215a139d7a48d069cd9)
(cherry picked from commit 9a4725f0341c71a9b4f50f2d203f9740029e42e5)
(cherry picked from commit a2c57345ffa5404cefd3d43e2fd4e4492ac7c6e0)
(cherry picked from commit df56458ca85c681d163d879b832f868ed5044c8e)
(cherry picked from commit dfc085aad98db2bcabd2c438fcd722a90303e6cb)
This commits preserves I/O-dispatch plugging for a special symmetric
case that may suddenly turn into asymmetric: the case where only one
bfq_queue, say bfqq, is busy. In this case, not expiring bfqq does not
cause any harm to any other queues in terms of service guarantees. In
contrast, it avoids the following unlucky sequence of events: (1) bfqq
is expired, (2) a new queue with a lower weight than bfqq becomes busy
(or more queues), (3) the new queue is served until a new request
arrives for bfqq, (4) when bfqq is finally served, there are so many
requests of the new queue in the drive that the pending requests for
bfqq take a lot of time to be served. In particular, event (2) may
case even already dispatched requests of bfqq to be delayed, inside
the drive. So, to avoid this series of events, the scenario is
preventively declared as asymmetric also if bfqq is the only busy
queues. By doing so, I/O-dispatch plugging is performed for bfqq.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 2391d13ed484df1515f0025458e1f82317823fab)
(cherry picked from commit 79827eb41d8fb0f838a2c592775a8e63caeb7c57)
(cherry picked from commit 41720669259995fb7f064fc0f988c9d228750b37)
(cherry picked from commit 07d273c955ea2c34a42f6de0f1e3f1bfb00c6ce1)
(cherry picked from commit 8034c856b8fcafbef405eedddc12bb0625e52a42)
(cherry picked from commit f49083d304bda30647196b550a109f528c8266dc)
(cherry picked from commit 8a597f0ab5e7e83bfa426d071185c3d3ce5fa535)
To prevent injection information from being lost on bfq_queue merging,
also the amount of service that a bfq_queue receives must be saved and
restored when the bfq_queue is merged and split, respectively.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 5a5436b98d5cd2714feaaa579cec49dd7f7057bb)
(cherry picked from commit 9372e98dc77c7f2ebbb808a60abb01f30d70d0bc)
(cherry picked from commit e6a5b66cfe56495f26182cfd2340e3336bb4b2b4)
(cherry picked from commit c579a3634d163ed05cc4ac258411f03db969926e)
(cherry picked from commit 359f87d07390f687634185b0dd9d6f106fb5afdd)
(cherry picked from commit d1d1f1336ed77b83e98d26175e196b45a28958f4)
(cherry picked from commit 0ff8068594640924e0cffe27d8b0273bb80d74ca)
To prevent weight-raising information from being lost on bfq_queue merging,
also the amount of service that a bfq_queue receives must be saved and
restored when the bfq_queue is merged and split, respectively.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit e673914d52f913584cc4c454dfcff2e8eb04533f)
(cherry picked from commit 48f3cf9bb6ae73de3e8e6cad2e50c6e70a6cd33f)
(cherry picked from commit d947cf3f8bcbcbe2dd8f5eec82e83a35198f874b)
(cherry picked from commit 39b91f1f22265c70cdc48916ac694dad6c21c191)
(cherry picked from commit 421c82648e46467d29dc0b5cd5522f00a026083d)
(cherry picked from commit e9eecde7c67303c1dc87864c10c372019d609b0b)
(cherry picked from commit 41d4c63679c36dc63b4cc9be301ec8d8d518d33f)
A bfq_queue may happen to be deemed as soft real-time while it is
still enjoying interactive weight-raising. If this happens because of
a false positive, then the bfq_queue is likely to loose its soft
real-time status soon. Upon losing such a status, the bfq_queue must
get back its interactive weight-raising, if its interactive period is
not over yet. But this case is not handled. This commit corrects this
error.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit d1f600fa4732dac36c71a03b790f0c829a076475)
(cherry picked from commit db891a7d6aed6cc37d681d2bbf6c9bd697059281)
(cherry picked from commit 647b877a9a8493df84a1d4abd94be089c8fed49b)
(cherry picked from commit 7eda6de0bbbfa1d05b8888b697d9b7aeffe4d64e)
(cherry picked from commit c1e076d9f4688c77dfa0f859060ae1f27a8d889e)
(cherry picked from commit db0058abb7534aeb0abebe01c65659aa3886de78)
(cherry picked from commit 40bc06529a2053ca0caf2053dd6f2a27bf7af916)
Upon an I/O-dispatch attempt, BFQ may detect that it was better to
plug I/O dispatch, and to wait for a new request to arrive for the
currently in-service queue. But the arrival of a new request for an
empty bfq_queue, and thus the switch from idle to busy of the
bfq_queue, may cause the scenario to change, and make plugging no
longer needed for service guarantees, or more convenient for
throughput. In this case, keeping I/O-dispatch plugged would certainly
lower throughput.
To address this issue, this commit makes such a check, and stops
plugging I/O if it is better to stop plugging I/O.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 7f1995c27b19060dbdff23442f375e3097c90707)
(cherry picked from commit 12ec5a8ca2486d06f880d41751383c0d9549ba49)
(cherry picked from commit 64c6efc5ccb01edf553487aff312c0b7110cb30f)
(cherry picked from commit 3e04c1949f447a8166fa6d6343bd5332d8c12a4b)
(cherry picked from commit 40a263c36cf2094311e8189b6e9173360a808b12)
(cherry picked from commit 61a02ce46503671c747e550a13972ca8abaf5030)
(cherry picked from commit 3707ff2d32dccd807b8e5e6885f07f3874c71180)
Use local variable 'ttime' instead of dereferencing bfqq.
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 28c6def009192b673f92ea357dfb535ba15e00a4)
(cherry picked from commit bb2a213aa0a2b717c3a6e7848c6f82656d80897f)
(cherry picked from commit 2e0cfffb9a6da88cb1a786fb95618bfa714fea32)
(cherry picked from commit caff780963fdfda0ab456c24027298482d745b2f)
(cherry picked from commit b893b660ea8e998b760d48faeed2834e483158ad)
(cherry picked from commit 7e3d952af5fdcf6b02d01d55dbf658fbc2d67f41)
(cherry picked from commit 033b49f66e3808fead9e65e7c9417f26d423374f)
Correct the comments since bfq_fifo_expire[0] is for async request,
while bfq_fifo_expire[1] is for sync request.
Also update docs, according the source code, the default
fifo_expire_async is 250ms, and fifo_expire_sync is 125ms.
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 4168a8d27ed3a00f160e7f885c956f060d2a0741)
(cherry picked from commit a31ff2eb7d7cfa8331e513bb282f304117f18a77)
(cherry picked from commit a78637befaa4106f9858b3ad8e3273960d3de82b)
(cherry picked from commit bd8e7d3845c7a3b602aee361c7e3d0b5764ce060)
(cherry picked from commit a8543954accfadbb9a1cf1f64c6b3749ee3a629b)
(cherry picked from commit 960981f44b77dcd0d4e786aaef72d39057ccfc03)
(cherry picked from commit 50cfb4b6c1c2e4a3778f66510fee7a2e86e053f2)
Suppose that I/O dispatch is plugged, to wait for new I/O for the
in-service bfq-queue, say bfqq. Suppose then that there is a further
bfq_queue woken by bfqq, and that this woken queue has pending I/O. A
woken queue does not steal bandwidth from bfqq, because it remains
soon without I/O if bfqq is not served. So there is virtually no risk
of loss of bandwidth for bfqq if this woken queue has I/O dispatched
while bfqq is waiting for new I/O. In contrast, this extra I/O
injection boosts throughput. This commit performs this extra
injection.
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/20210304174627.161-2-paolo.valente@linaro.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 2ec5a5c48373d4bc2f0699f86507a65bf0b9df35)
(cherry picked from commit 0750db9767232fc2e4850868e526f4b02ecfb247)
(cherry picked from commit 8676f43249bbb0478a8b18bd87703da59902dbfd)
(cherry picked from commit df655d250f253a2f8a6792569108f30a04b7b894)
(cherry picked from commit d76168c1c3805a2c948e7ff60c8eb341e2ff0013)
(cherry picked from commit f213ae4e575f8ed67ae065fe80d06dc957f0b068)
(cherry picked from commit eb1ff3ab6d66081fbaf007c6cfc1a5e841719c0c)
Lockdep complains about lock inversion between ioc->lock and bfqd->lock:
bfqd -> ioc:
put_io_context+0x33/0x90 -> ioc->lock grabbed
blk_mq_free_request+0x51/0x140
blk_put_request+0xe/0x10
blk_attempt_req_merge+0x1d/0x30
elv_attempt_insert_merge+0x56/0xa0
blk_mq_sched_try_insert_merge+0x4b/0x60
bfq_insert_requests+0x9e/0x18c0 -> bfqd->lock grabbed
blk_mq_sched_insert_requests+0xd6/0x2b0
blk_mq_flush_plug_list+0x154/0x280
blk_finish_plug+0x40/0x60
ext4_writepages+0x696/0x1320
do_writepages+0x1c/0x80
__filemap_fdatawrite_range+0xd7/0x120
sync_file_range+0xac/0xf0
ioc->bfqd:
bfq_exit_icq+0xa3/0xe0 -> bfqd->lock grabbed
put_io_context_active+0x78/0xb0 -> ioc->lock grabbed
exit_io_context+0x48/0x50
do_exit+0x7e9/0xdd0
do_group_exit+0x54/0xc0
To avoid this inversion we change blk_mq_sched_try_insert_merge() to not
free the merged request but rather leave that upto the caller similarly
to blk_mq_sched_try_merge(). And in bfq_insert_requests() we make sure
to free all the merged requests after dropping bfqd->lock.
Fixes: aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210623093634.27879-3-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit fd2ef39cc9a6b9c4c41864ac506906c52f94b06a)
(cherry picked from commit 786e392c4a7bd2559bdc1a1c6ac28d8b612a0735)
(cherry picked from commit aa8e3e1451bde73dff60f1e5110b6a3cb810e35b)
(cherry picked from commit 4deef6abb13a82b148c583d9ab37374c876fe4c2)
(cherry picked from commit 1988f864ec1c494bb54e5b9df1611195f6d923f2)
(cherry picked from commit 9dc0074b0dd8960f9e06dc1494855493ff53eb68)
(cherry picked from commit c937983724111bb4526e34da0d5c6c8aea1902af)
