[SPDK] Re: Single iSCSI max performance with SPDK NULL Block Device

Ah, you're is ng null bdev, so my reference to the SSD being an issue is
irrelevant. At 40 Gig, you should be running much faster than  155 KIOPS,
and the target threading may be an issue. OTOH, single poller with null
bdev has been shown to reach 10 MIOPS, so I'd also look into your network
setup.

Regards,
Andrey

On Wed, Dec 9, 2020, 16:51 Lego Lin <lego.lin(a)gmail.com> wrote:

> Hi,  Andrey
>
> Thanks for quick reply. I will try 20.10.
> Sorry for providing wrong information. Single target with SPDK NULL BDev
> under 40G nic card, I got
> 100%RandWrite 4K : 135K
> 100%RandRead 4K : 155K
>
> Although 135K for 1 SSD random write is enough, but not enough for read.
> And if I compose 4 SSD into 1 raid-0 BDev, 135K is not enough.
>
> Anyway, I will try 20.10 first. Thanks again
>
> On Wed, Dec 9, 2020 at 8:36 PM Andrey Kuzmin <andrey.v.kuzmin(a)gmail.com>
> wrote:
>
> > On Wed, Dec 9, 2020, 15:14 Lego Lin <lego.lin(a)gmail.com> wrote:
> >
> > > Hi,
> > >
> > > Currently, I am using SPDK 19.04 evaluating SPDK iSCSI Performance. As
> >
> > I know, current SPDK iSCSI only uses 1 reactor to handle 1 target's iSCSI
> > > IO.
> > > When I try with SPDK NULL Block Device, the max performance with
> > > 100%RandWrite / 40G NIC / BS = 4K is about 155K.
> > >
> >
> > At 155K random write IOPS, the bottleneck can easily be in the actual SSD
> > being used. Have you tested w/o SPDK iSCSI target being involved, with
> the
> > same SSD in the direct attachment settings?
> >
> > Also, 19.04 is 1.5 years old, so you might want to upgrade to 20.10.
> >
> > Regards,
> > Andrey
> >
> > I try to finish IO immediately at different layer : SPDK BDev Layer, SCSI
> > > Layer.
> > > It looks like iSCSI protocol handling become the bottleneck of SPDK
> NULL
> > > Block Device.
> > > Is there any way in SPDK to let multiple reactors handle 1 iSCSI target
> > > IOs?
> > >
> > > Current test topology as following:
> >
> >
> > > Client: FIO <--> /dev/sdb (Test 1: with 1 thread + with/without blk-mq,
> > > Test 2: with 4 threads  + with/without blk-mq)
> > > Target: 1 SPDK iSCSI target <--> 1 LUN <--> SPDK NULL Block Device
> >
> >
> > > Thanks
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