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

[Kanchan Joshi]

On Sat, Sep 03, 2022 at 11:00:43AM -0600, Jens Axboe wrote:
>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!
Great! In my setup (single disk/numa-node), current kernel shows-

Block MIOPS
***********
command:t/io_uring -b512 -d128 -c32 -s32 -p0 -F1 -B0 -P1 -n1 /dev/nvme0n1
plain: 1.52
plain+fb: 1.77
plain+poll: 2.23
plain+fb+poll: 2.61

Passthru MIOPS
**************
command:t/io_uring -b512 -d128 -c32 -s32 -p0 -F1 -B0 -O0 -P1 -u1 -n1 /dev/ng0n1
plain: 1.78
plain+fb: 2.08
plain+poll: 2.21
plain+fb+poll: 2.69