Re: [PATCH -next 00/11] support concurrent sync io for bfq on a specail occasion

[yukuai (C)]

friendly ping ...

在 2022/04/01 11:43, yukuai (C) 写道:
> friendly ping ...
>
> 在 2022/03/25 15:30, yukuai (C) 写道:
> > friendly ping ...
> >
> > 在 2022/03/17 9:49, yukuai (C) 写道:
> > > friendly ping ...
> > >
> > > 在 2022/03/11 14:31, yukuai (C) 写道:
> > > > friendly ping ...
> > > >
> > > > 在 2022/03/05 17:11, Yu Kuai 写道:
> > > > > 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(-)