Messages in this thread | | | From | Yu Kuai <> | Subject | [PATCH -next 00/11] support concurrent sync io for bfq on a specail occasion | Date | Sat, 5 Mar 2022 17:11:54 +0800 |
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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().
This patchset tries to support concurrent sync io if all the sync ios are issued from the same cgroup:
1) Count root_group into 'num_groups_with_pending_reqs', patch 1-5;
2) Don't idle if 'num_groups_with_pending_reqs' is 1, patch 6;
3) Don't count the group if the group doesn't have pending requests, while it's child groups may have pending requests, patch 7;
This is because, for example: if sync ios are issued from cgroup /root/c1/c2, root, c1 and c2 will all be counted into 'num_groups_with_pending_reqs', which makes it impossible to handle sync ios concurrently.
4) Decrease 'num_groups_with_pending_reqs' when the last queue completes all the requests, while child groups may still have pending requests, patch 8-10;
This is because, for example: t1 issue sync io on root group, t2 and t3 issue sync io on the same child group. num_groups_with_pending_reqs is 2 now. After t1 stopped, num_groups_with_pending_reqs is still 2. sync io from t2 and t3 still can't be handled concurrently.
fio test script: startdelay is used to avoid queue merging [global] filename=/dev/nvme0n1 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 v5.17-rc6: 550 Mib/s v5.17-rc6-patched: 550 Mib/s
running fio on non-root cgroup v5.17-rc6: 349 Mib/s v5.17-rc6-patched: 550 Mib/s
Yu Kuai (11): block, bfq: add new apis to iterate bfq entities block, bfq: apply news apis where root group is not expected block, bfq: cleanup for __bfq_activate_requeue_entity() block, bfq: move the increasement of 'num_groups_with_pending_reqs' to it's caller block, bfq: count root group into 'num_groups_with_pending_reqs' block, bfq: do not idle if only one cgroup is activated block, bfq: only count parent bfqg when bfqq is activated block, bfq: record how many queues have pending requests in bfq_group block, bfq: move forward __bfq_weights_tree_remove() block, bfq: decrease 'num_groups_with_pending_reqs' earlier block, bfq: cleanup bfqq_group()
block/bfq-cgroup.c | 13 +++---- block/bfq-iosched.c | 87 +++++++++++++++++++++++---------------------- block/bfq-iosched.h | 41 +++++++++++++-------- block/bfq-wf2q.c | 56 +++++++++++++++-------------- 4 files changed, 106 insertions(+), 91 deletions(-)
-- 2.31.1
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