Messages in this thread | | | Subject | Re: [PATCH RFC 0/9] support concurrent sync io for bfq on a specail occasion | From | "yukuai (C)" <> | Date | Fri, 10 Dec 2021 17:50:34 +0800 |
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在 2021/12/10 17:20, Paolo Valente 写道: > > >> Il giorno 27 nov 2021, alle ore 11:11, Yu Kuai <yukuai3@huawei.com> ha scritto: >> >> Bfq can't handle sync io concurrently as long as the io are not issued >> from root group currently. >> >> Previous patch set: >> https://lore.kernel.org/lkml/20211014014556.3597008-2-yukuai3@huawei.com/t/ >> >> During implemting the method mentioned by the above patch set, I found >> more problems that will block implemting concurrent sync io. The >> modifications of this patch set are as follows: >> >> 1) count root group into 'num_groups_with_pending_reqs'; >> 2) don't idle if 'num_groups_with_pending_reqs' is 1; >> 3) If the group doesn't have pending requests while it's child groups >> have pending requests, don't count the group. > > Why don't yo count the parent group? It seems to me that we should count it. Hi, Paolo
For example, we only issue io in child group c2(root->c1->c2), 'num_groups_with_pending_reqs' will end up greater than 1, thus it's impossible to handle sync io concurrently. Thus I don't count root and c1, only count c2. > >> 4) Once the group doesn't have pending requests, decrease >> 'num_groups_with_pending_reqs' immediately. Don't delay to when all >> it's child groups don't have pending requests. >> > > I guess this action is related to 3). Yes, if c1, c2 are both active, and then c1 don't have any pending reqs, I want to decrease num_groups_with_pending_reqs to 1 immediately. So that sync io on c2 can be handled concurrently.
Thanks, Kuai
> > Thanks, > Paolo > >> Noted that I just tested basic functionality of this patchset, and I >> think it's better to see if anyone have suggestions or better >> solutions. >> >> Yu Kuai (9): >> block, bfq: add new apis to iterate bfq entities >> block, bfq: apply news apis where root group is not expected >> block, bfq: handle the case when for_each_entity() access root group >> 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 group that the bfq_queue belongs to >> 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-cgroup.c | 3 +- >> block/bfq-iosched.c | 92 +++++++++++++++++++++++---------------------- >> block/bfq-iosched.h | 41 +++++++++++++------- >> block/bfq-wf2q.c | 44 +++++++++++++++------- >> 4 files changed, 106 insertions(+), 74 deletions(-) >> >> -- >> 2.31.1 >> > > . >
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