If so, can you check with e.g.
perf record -ags -e LLC-load-misses sleep 10 && perf report whether this
workload triggers perhaps lock contention ? What you need to look for in
the perf output is whether any functions occupy more than 10% CPU time.
I will, thanks for the tip!
The perf report is very similar to the one that started this effort..
I'm afraid we'll need to resolve the per-target m->lock in order
to scale with NUMA...
- 17.33% fio [kernel.kallsyms] [k]
queued_spin_lock_slowpath
- queued_spin_lock_slowpath
- 52.09% _raw_spin_lock_irq
__multipath_map
multipath_clone_and_map
map_request
dm_mq_queue_rq
__blk_mq_run_hw_queue
blk_mq_run_hw_queue
blk_mq_insert_requests
blk_mq_flush_plug_list
blk_flush_plug_list
blk_finish_plug
do_io_submit
SyS_io_submit
entry_SYSCALL_64_fastpath
+ io_submit
- 46.87% _raw_spin_lock_irqsave
- 99.97% multipath_busy
dm_mq_queue_rq
__blk_mq_run_hw_queue
blk_mq_run_hw_queue
blk_mq_insert_requests
blk_mq_flush_plug_list
blk_flush_plug_list
blk_finish_plug
do_io_submit
SyS_io_submit
entry_SYSCALL_64_fastpath
+ io_submit
+ 4.99% fio [kernel.kallsyms] [k]
blk_account_io_start
+ 3.93% fio [dm_multipath] [k] __multipath_map
+ 2.64% fio [dm_multipath] [k] multipath_busy
+ 2.38% fio [kernel.kallsyms] [k]
_raw_spin_lock_irqsave
+ 2.31% fio [dm_mod] [k] dm_mq_queue_rq
+ 2.25% fio [kernel.kallsyms] [k]
blk_mq_hctx_mark_pending
+ 1.81% fio [kernel.kallsyms] [k] blk_queue_enter
+ 1.61% perf [kernel.kallsyms] [k]
copy_user_generic_string
+ 1.40% fio [kernel.kallsyms] [k]
__blk_mq_run_hw_queue
+ 1.26% fio [kernel.kallsyms] [k] part_round_stats
+ 1.14% fio [kernel.kallsyms] [k] _raw_spin_lock_irq
+ 0.96% fio [kernel.kallsyms] [k] __bt_get
+ 0.73% fio [kernel.kallsyms] [k] enqueue_task_fair
+ 0.71% fio [kernel.kallsyms] [k] enqueue_entity
+ 0.69% fio [dm_mod] [k] dm_start_request
+ 0.60% ksoftirqd/6 [kernel.kallsyms] [k]
blk_mq_run_hw_queues
+ 0.59% ksoftirqd/10 [kernel.kallsyms] [k]
blk_mq_run_hw_queues
+ 0.59% fio [kernel.kallsyms] [k]
_raw_spin_unlock_irqrestore
+ 0.58% ksoftirqd/19 [kernel.kallsyms] [k]
blk_mq_run_hw_queues
+ 0.58% ksoftirqd/18 [kernel.kallsyms] [k]
blk_mq_run_hw_queues
+ 0.58% ksoftirqd/23 [kernel.kallsyms] [k]
blk_mq_run_hw_queues
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