On 02/07/16 07:41, Sagi Grimberg wrote:
FYI, here is the latest revised patch:
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.6&id=a5b835282422ec41991c1dbdb88daa4af7d166d2
(revised patch header and fixed a thinko in the dm.c:rq_completed()
change from the RFC patch I posted earlier)
Hi Mike,
So I gave your patches a go (dm-4.6) but I still don't see the
improvement you reported (while I do see a minor improvement).
null_blk queue_mode=2 submit_queues=24
dm_mod blk_mq_nr_hw_queues=24 blk_mq_queue_depth=4096 use_blk_mq=Y
I see 620K IOPs on dm_mq vs. 1750K IOPs on raw nullb0.
Is there something I'm missing?
Hello Sagi,
Did you run your test on a NUMA system ? 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.
Bart.
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