Re: [PATCH for-next v3 0/4] fixed-buffer for uring-cmd/passthrough

Jens Axboe
2022-09-03T17:01:06Z

On 9/2/22 3:25 PM, Jens Axboe wrote:
> On 9/2/22 1:32 PM, Jens Axboe wrote:
>> On 9/2/22 12:46 PM, Kanchan Joshi wrote:
>>> On Fri, Sep 02, 2022 at 10:32:16AM -0600, Jens Axboe wrote:
>>>> On 9/2/22 10:06 AM, Jens Axboe wrote:
>>>>> On 9/2/22 9:16 AM, Kanchan Joshi wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Currently uring-cmd lacks the ability to leverage the pre-registered
>>>>>> buffers. This series adds the support in uring-cmd, and plumbs
>>>>>> nvme passthrough to work with it.
>>>>>>
>>>>>> Using registered-buffers showed peak-perf hike from 1.85M to 2.17M IOPS
>>>>>> in my setup.
>>>>>>
>>>>>> Without fixedbufs
>>>>>> *****************
>>>>>> # taskset -c 0 t/io_uring -b512 -d128 -c32 -s32 -p0 -F1 -B0 -O0 -n1 -u1 /dev/ng0n1
>>>>>> submitter=0, tid=5256, file=/dev/ng0n1, node=-1
>>>>>> polled=0, fixedbufs=0/0, register_files=1, buffered=1, QD=128
>>>>>> Engine=io_uring, sq_ring=128, cq_ring=128
>>>>>> IOPS=1.85M, BW=904MiB/s, IOS/call=32/31
>>>>>> IOPS=1.85M, BW=903MiB/s, IOS/call=32/32
>>>>>> IOPS=1.85M, BW=902MiB/s, IOS/call=32/32
>>>>>> ^CExiting on signal
>>>>>> Maximum IOPS=1.85M
>>>>>
>>>>> With the poll support queued up, I ran this one as well. tldr is:
>>>>>
>>>>> bdev (non pt)??? 122M IOPS
>>>>> irq driven??? 51-52M IOPS
>>>>> polled??????? 71M IOPS
>>>>> polled+fixed??? 78M IOPS

Followup on this, since t/io_uring didn't correctly detect NUMA nodes
for passthrough.

With the current tree and the patchset I just sent for iopoll and the
caching fix that's in the block tree, here's the final score:

polled+fixed passthrough 105M IOPS

which is getting pretty close to the bdev polled fixed path as well.
I think that is starting to look pretty good!

[...]
submitter=22, tid=4768, file=/dev/ng22n1, node=8
submitter=23, tid=4769, file=/dev/ng23n1, node=8
polled=1, fixedbufs=1/0, register_files=1, buffered=1, QD=128
Engine=io_uring, sq_ring=128, cq_ring=128
IOPS=102.51M, BW=50.05GiB/s, IOS/call=32/31
IOPS=105.29M, BW=51.41GiB/s, IOS/call=31/32
IOPS=105.34M, BW=51.43GiB/s, IOS/call=32/31
IOPS=105.37M, BW=51.45GiB/s, IOS/call=32/32
IOPS=105.37M, BW=51.45GiB/s, IOS/call=31/31
IOPS=105.38M, BW=51.45GiB/s, IOS/call=31/31
IOPS=105.35M, BW=51.44GiB/s, IOS/call=32/32
IOPS=105.49M, BW=51.51GiB/s, IOS/call=32/31
^CExiting on signal
Maximum IOPS=105.49M

--
Jens Axboe