linux-kernel - Re: [PATCH 0/4] nvmet: support polling queue task for bio

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Date:   Tue, 19 Sep 2023 11:25:38 +0800
From:   Ping Gan <jacky_gam_2001@....com>
To:     chaitanyak@...dia.com
Cc:     ping_gan@...l.com, kbusch@...nel.org,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        hch@....de, sagi@...mberg.me, axboe@...nel.dk,
        jacky_gam_2001@....com
Subject: Re: [PATCH 0/4] nvmet: support polling queue task for bio

> On 9/13/2023 1:34 AM, Ping Gan wrote:
> > Since nvme target currently does not support to submit bio to a
> > polling
> > queue, the bio's completion relies on system interrupt. But when
> > there
> > is high workload in system and the competition is very high, so it
> > makes
> > sense to add polling queue task to submit bio to disk's polling
> > queue
> > and poll the completion queue of disk.
> > 
> >
>
> I did some work in the past for nvmet polling and saw good
> performance improvement.
>
> Can you please share performance numbers for this series ?
> 
> -ck

hi,
I have verified this patch on two testbeds one for host and the other
for target. I used tcp as transport protocol, spdk perf as initiator. 
I did two group tests. The IO size of first is 4K, and the other is 2M.
Both include randrw, randwrite and randrw. Both also have same prerequisites.
At the initiator side I used 1 qp, 32 queue depth,and 1 spdk perf
application, and for target side I bound tcp queue to 1 target core.
And I get below results.
iosize_4k        polling queue                        interrupt
randrw           NIC_rx:338M/s NIC_tx:335M/s      NIC_rx:260M/s
NIC_tx:258M/s
randwrite        NIC_rx:587M/s                    NIC_rx:431M/s
randread         NIC_tx:873M/s                    NIC_tx:654M/s

iosize_2M        polling queue                        interrupt
randrw           NIC_rx:738M/s NIC_tx:741M/s      NIC_rx:674M/s
NIC_tx:674M/s
randwrite        NIC_rx:1199M/s                   NIC_rx:1146M/s
randread         NIC_tx:2226M/s                   NIC_tx:2119M/s

For iosize 4k the NIC's bandwidth of poling queue is more than 30% than
bandwidth of interrupt. But for iosize 2M the improvement is not
obvious,
the randrw of polling queue is about 9% more than interrupt; randwrite
and randread of polling queue is about 5% more than interrupt.

Thanks,
Ping