> Il giorno 23 mag 2022, alle ore 15:18, Yu Kuai <yukuai3@xxxxxxxxxx> ha scritto: > > Resend these patches just in case v5 end up in spam (for Paolo). Thank you for resending, I do think I lost some email before. Paolo > 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 have at least one bfqq that is marked busy. > 3) Don't count if bfqg doesn't have any busy bfqqs. > > The main reason to use busy state of bfqq instead of 'pending requests' > is that bfqq can stay busy after dispatching the last request if idling > is needed for service guarantees. > > 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/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 > v5.18-rc1: 550 Mib/s > v5.18-rc1-patched: 550 Mib/s > > running fio on non-root cgroup > v5.18-rc1: 349 Mib/s > v5.18-rc1-patched: 550 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. > > Follow-up cleanup: > https://lore.kernel.org/all/20220521073523.3118246-1-yukuai3@xxxxxxxxxx/ > > Previous versions: > RFC: https://lore.kernel.org/all/20211127101132.486806-1-yukuai3@xxxxxxxxxx/ > v1: https://lore.kernel.org/all/20220305091205.4188398-1-yukuai3@xxxxxxxxxx/ > v2: https://lore.kernel.org/all/20220416093753.3054696-1-yukuai3@xxxxxxxxxx/ > v3: https://lore.kernel.org/all/20220427124722.48465-1-yukuai3@xxxxxxxxxx/ > v4: https://lore.kernel.org/all/20220428111907.3635820-1-yukuai3@xxxxxxxxxx/ > v5: https://lore.kernel.org/all/20220428120837.3737765-1-yukuai3@xxxxxxxxxx/ > > Yu Kuai (3): > block, bfq: record how many queues are busy in bfq_group > 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 | 1 + > block/bfq-iosched.c | 48 +++----------------------------------- > block/bfq-iosched.h | 57 +++++++-------------------------------------- > block/bfq-wf2q.c | 35 +++++++++++++++++----------- > 4 files changed, 35 insertions(+), 106 deletions(-) > > -- > 2.31.1 >
