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Date:   Thu, 21 Mar 2019 16:13:52 +0000
From:   Stefan Hajnoczi <stefanha@gmail.com>
To:     Maxim Levitsky <mlevitsk@redhat.com>
Cc:     linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, Jens Axboe <axboe@fb.com>,
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        Sagi Grimberg <sagi@grimberg.me>,
        Kirti Wankhede <kwankhede@nvidia.com>,
        "David S . Miller" <davem@davemloft.net>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        Nicolas Ferre <nicolas.ferre@microchip.com>,
        "Paul E . McKenney " <paulmck@linux.ibm.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Liang Cunming <cunming.liang@intel.com>,
        Liu Changpeng <changpeng.liu@intel.com>,
        Fam Zheng <fam@euphon.net>, Amnon Ilan <ailan@redhat.com>,
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On Tue, Mar 19, 2019 at 04:41:07PM +0200, Maxim Levitsky wrote:
> Date: Tue, 19 Mar 2019 14:45:45 +0200
> Subject: [PATCH 0/9] RFC: NVME VFIO mediated device
>=20
> Hi everyone!
>=20
> In this patch series, I would like to introduce my take on the problem of=
 doing=20
> as fast as possible virtualization of storage with emphasis on low latenc=
y.
>=20
> In this patch series I implemented a kernel vfio based, mediated device t=
hat=20
> allows the user to pass through a partition and/or whole namespace to a g=
uest.
>=20
> The idea behind this driver is based on paper you can find at
> https://www.usenix.org/conference/atc18/presentation/peng,
>=20
> Although note that I stared the development prior to reading this paper,=
=20
> independently.
>=20
> In addition to that implementation is not based on code used in the paper=
 as=20
> I wasn't being able at that time to make the source available to me.
>=20
> ***Key points about the implementation:***
>=20
> * Polling kernel thread is used. The polling is stopped after a=20
> predefined timeout (1/2 sec by default).
> Support for all interrupt driven mode is planned, and it shows promising =
results.
>=20
> * Guest sees a standard NVME device - this allows to run guest with=20
> unmodified drivers, for example windows guests.
>=20
> * The NVMe device is shared between host and guest.
> That means that even a single namespace can be split between host=20
> and guest based on different partitions.
>=20
> * Simple configuration
>=20
> *** Performance ***
>=20
> Performance was tested on Intel DC P3700, With Xeon E5-2620 v2=20
> and both latency and throughput is very similar to SPDK.
>=20
> Soon I will test this on a better server and nvme device and provide
> more formal performance numbers.
>=20
> Latency numbers:
> ~80ms - spdk with fio plugin on the host.
> ~84ms - nvme driver on the host
> ~87ms - mdev-nvme + nvme driver in the guest

You mentioned the spdk numbers are with vhost-user-nvme.  Have you
measured SPDK's vhost-user-blk?

Stefan

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