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SubjectRe: [PATCH -next v9 0/4] support concurrent sync io for bfq on a specail occasion
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在 2022/06/01 19:43, Yu Kuai 写道:

Hi, Paolo

Since there is no response from you, I assum that you didn't receive
these emails(probably end up in your spam). I'll try to resend them
soon.

Thanks,
Kuai
> Changes in v9:
> - also update how many bfqqs have pending_reqs bfq_bfqq_move().
> - fix one language in patch 4
> - Add reviewed-tag for patch 1,3,4
>
> Changes in v8:
> - Instead of using whether bfqq is busy, using whether bfqq has pending
> requests. As Paolo pointed out the former way is problematic.
>
> Changes in v7:
> - fix mismatch bfq_inc/del_busy_queues() and bfqq_add/del_bfqq_busy(),
> also retest this patchset on v5.18 to make sure functionality is
> correct.
> - move the updating of 'bfqd->busy_queues' into new apis
>
> Changes in v6:
> - add reviewed-by tag for patch 1
>
> Changes in v5:
> - rename bfq_add_busy_queues() to bfq_inc_busy_queues() in patch 1
> - fix wrong definition in patch 1
> - fix spelling mistake in patch 2: leaset -> least
> - update comments in patch 3
> - add reviewed-by tag in patch 2,3
>
> Changes in v4:
> - split bfq_update_busy_queues() to bfq_add/dec_busy_queues(),
> suggested by Jan Kara.
> - remove unused 'in_groups_with_pending_reqs',
>
> Changes in v3:
> - remove the cleanup patch that is irrelevant now(I'll post it
> separately).
> - instead of hacking wr queues and using weights tree insertion/removal,
> using bfq_add/del_bfqq_busy() to count the number of groups
> (suggested by Jan Kara).
>
> Changes in v2:
> - Use a different approch to count root group, which is much simple.
>
> Currently, bfq can't handle sync io concurrently as long as they
> are not issued from root group. This is because
> 'bfqd->num_groups_with_pending_reqs > 0' is always true in
> bfq_asymmetric_scenario().
>
> The way that bfqg is counted into 'num_groups_with_pending_reqs':
>
> Before this patchset:
> 1) root group will never be counted.
> 2) Count if bfqg or it's child bfqgs have pending requests.
> 3) Don't count if bfqg and it's child bfqgs complete all the requests.
>
> After this patchset:
> 1) root group is counted.
> 2) Count if bfqg has pending requests.
> 3) Don't count if bfqg complete all the requests.
>
> With the above changes, concurrent sync io can be supported if only
> one group is activated.
>
> fio test script(startdelay is used to avoid queue merging):
> [global]
> filename=/dev/sda
> allow_mounted_write=0
> ioengine=psync
> direct=1
> ioscheduler=bfq
> offset_increment=10g
> group_reporting
> rw=randwrite
> bs=4k
>
> [test1]
> numjobs=1
>
> [test2]
> startdelay=1
> numjobs=1
>
> [test3]
> startdelay=2
> numjobs=1
>
> [test4]
> startdelay=3
> numjobs=1
>
> [test5]
> startdelay=4
> numjobs=1
>
> [test6]
> startdelay=5
> numjobs=1
>
> [test7]
> startdelay=6
> numjobs=1
>
> [test8]
> startdelay=7
> numjobs=1
>
> test result:
> running fio on root cgroup
> v5.18: 112 Mib/s
> v5.18-patched: 112 Mib/s
>
> running fio on non-root cgroup
> v5.18: 51.2 Mib/s
> v5.18-patched: 112 Mib/s
>
> Note that I also test null_blk with "irqmode=2
> completion_nsec=100000000(100ms) hw_queue_depth=1", and tests show
> that service guarantees are still preserved.
>
> Previous versions:
> RFC: https://lore.kernel.org/all/20211127101132.486806-1-yukuai3@huawei.com/
> v1: https://lore.kernel.org/all/20220305091205.4188398-1-yukuai3@huawei.com/
> v2: https://lore.kernel.org/all/20220416093753.3054696-1-yukuai3@huawei.com/
> v3: https://lore.kernel.org/all/20220427124722.48465-1-yukuai3@huawei.com/
> v4: https://lore.kernel.org/all/20220428111907.3635820-1-yukuai3@huawei.com/
> v5: https://lore.kernel.org/all/20220428120837.3737765-1-yukuai3@huawei.com/
> v6: https://lore.kernel.org/all/20220523131818.2798712-1-yukuai3@huawei.com/
> v7: https://lore.kernel.org/all/20220528095020.186970-1-yukuai3@huawei.com/
>
>
> Yu Kuai (4):
> block, bfq: support to track if bfqq has pending requests
> block, bfq: record how many queues have pending requests
> block, bfq: refactor the counting of 'num_groups_with_pending_reqs'
> block, bfq: do not idle if only one group is activated
>
> block/bfq-cgroup.c | 10 ++++++++++
> block/bfq-iosched.c | 47 +++------------------------------------------
> block/bfq-iosched.h | 21 +++++++++++---------
> block/bfq-wf2q.c | 47 ++++++++++++++++++++++++++++++---------------
> 4 files changed, 57 insertions(+), 68 deletions(-)
>

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