From: Keith Busch <kbusch@kernel.org>
To: Felipe Franciosi <felipe@nutanix.com>
Cc: Maxim Levitsky <mlevitsk@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>, Fam Zheng <fam@euphon.net>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Wolfram Sang <wsa@the-dreams.de>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Keith Busch <keith.busch@intel.com>,
Kirti Wankhede <kwankhede@nvidia.com>,
Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
"Paul E . McKenney" <paulmck@linux.ibm.com>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
"Harris, James R" <james.r.harris@intel.com>,
Liang Cunming <cunming.liang@intel.com>,
Jens Axboe <axboe@fb.com>,
Alex Williamson <alex.williamson@redhat.com>,
Thanos Makatos <thanos.makatos@nutanix.com>,
Subject: Re:
Date: Fri, 22 Mar 2019 09:30:25 -0600 [thread overview]
Message-ID: <20190322153025.GA31194@localhost.localdomain> (raw)
In-Reply-To: <0E8918CB-F679-4A5C-92AD-239E9CEC260C@nutanix.com>
On Fri, Mar 22, 2019 at 07:54:50AM +0000, Felipe Franciosi wrote:
> >
> > Note though that SPDK doesn't support sharing the device between host and the
> > guests, it takes over the nvme device, thus it makes the kernel nvme driver
> > unbind from it.
>
> That is absolutely true. However, I find it not to be a problem in practice.
>
> Hypervisor products, specially those caring about performance, efficiency and fairness, will dedicate NVMe devices for a particular purpose (eg. vDisk storage, cache, metadata) and will not share these devices for other use cases. That's because these products want to deterministically control the performance aspects of the device, which you just cannot do if you are sharing the device with a subsystem you do not control.
I don't know, it sounds like you've traded kernel syscalls for IPC,
and I don't think one performs better than the other.
> For scenarios where the device must be shared and such fine grained control is not required, it looks like using the kernel driver with io_uring offers very good performance with flexibility.
NVMe's IO Determinism features provide fine grained control for shared
devices. It's still uncommon to find hardware supporting that, though.
next prev parent reply other threads:[~2019-03-22 15:30 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-19 14:41 (unknown) Maxim Levitsky
2019-03-19 14:41 ` [PATCH 1/9] vfio/mdev: add .request callback Maxim Levitsky
2019-03-19 14:41 ` [PATCH 2/9] nvme/core: add some more values from the spec Maxim Levitsky
2019-03-19 14:41 ` [PATCH 3/9] nvme/core: add NVME_CTRL_SUSPENDED controller state Maxim Levitsky
2019-03-19 14:41 ` [PATCH 4/9] nvme/pci: use the NVME_CTRL_SUSPENDED state Maxim Levitsky
2019-03-20 2:54 ` Fam Zheng
2019-03-19 14:41 ` [PATCH 5/9] nvme/pci: add known admin effects to augument admin effects log page Maxim Levitsky
2019-03-19 14:41 ` [PATCH 6/9] nvme/pci: init shadow doorbell after each reset Maxim Levitsky
2019-03-19 14:41 ` [PATCH 7/9] nvme/core: add mdev interfaces Maxim Levitsky
2019-03-20 11:46 ` Stefan Hajnoczi
2019-03-20 12:50 ` Maxim Levitsky
2019-03-19 14:41 ` [PATCH 8/9] nvme/core: add nvme-mdev core driver Maxim Levitsky
2019-03-19 14:41 ` [PATCH 9/9] nvme/pci: implement the mdev external queue allocation interface Maxim Levitsky
2019-03-19 14:58 ` [PATCH 0/9] RFC: NVME VFIO mediated device Maxim Levitsky
2019-03-25 18:52 ` [PATCH 0/9] RFC: NVME VFIO mediated device [BENCHMARKS] Maxim Levitsky
2019-03-26 9:38 ` Stefan Hajnoczi
2019-03-26 9:50 ` Maxim Levitsky
2019-03-19 15:22 ` your mail Keith Busch
2019-03-19 23:49 ` Chaitanya Kulkarni
2019-03-20 16:44 ` Maxim Levitsky
2019-03-20 16:30 ` Maxim Levitsky
2019-03-20 17:03 ` Keith Busch
2019-03-20 17:33 ` Maxim Levitsky
2019-04-08 10:04 ` Maxim Levitsky
2019-03-20 11:03 ` Felipe Franciosi
2019-03-20 19:08 ` Re: Maxim Levitsky
2019-03-21 16:12 ` Re: Stefan Hajnoczi
2019-03-21 16:21 ` Re: Keith Busch
2019-03-21 16:41 ` Re: Felipe Franciosi
2019-03-21 17:04 ` Re: Maxim Levitsky
2019-03-22 7:54 ` Re: Felipe Franciosi
2019-03-22 10:32 ` Re: Maxim Levitsky
2019-03-22 15:30 ` Keith Busch [this message]
2019-03-25 15:44 ` Re: Felipe Franciosi
2019-03-20 15:08 ` [PATCH 0/9] RFC: NVME VFIO mediated device Bart Van Assche
2019-03-20 16:48 ` Maxim Levitsky
2019-03-20 15:28 ` Bart Van Assche
2019-03-20 16:42 ` Maxim Levitsky
2019-03-20 17:03 ` Alex Williamson
2019-03-21 16:13 ` your mail Stefan Hajnoczi
2019-03-21 17:07 ` Maxim Levitsky
2019-03-25 16:46 ` Stefan Hajnoczi
-- strict thread matches above, loose matches on Subject: below --
2022-01-14 10:54 Li RongQing
2022-01-14 10:55 ` Paolo Bonzini
2022-01-14 17:13 ` Re: Sean Christopherson
2022-01-14 17:17 ` Re: Paolo Bonzini
[not found] <E1hUrZM-0007qA-Q8@sslproxy01.your-server.de>
2019-05-29 19:54 ` Re: Alex Williamson
2018-02-05 5:28 Re: Fahama Vaserman
2017-11-13 14:44 Re: Amos Kalonzo
[not found] <CAMj-D2DO_CfvD77izsGfggoKP45HSC9aD6auUPAYC9Yeq_aX7w@mail.gmail.com>
2017-05-04 16:44 ` Re: gengdongjiu
2017-02-23 15:09 Qin's Yanjun
[not found] <D0613EBE33E8FD439137DAA95CCF59555B7A5A4D@MGCCCMAIL2010-5.mgccc.cc.ms.us>
2015-11-24 13:21 ` RE: Amis, Ryann
2014-04-13 21:01 (unknown), Marcus White
2014-04-15 0:59 ` Marcus White
2014-04-16 21:17 ` Re: Marcelo Tosatti
2014-04-17 21:33 ` Re: Marcus White
2014-04-21 21:49 ` Re: Marcelo Tosatti
2013-06-28 10:14 Re: emirates
2013-06-28 10:12 Re: emirates
2013-06-27 21:21 Re: emirates
2011-10-29 21:27 Re: Young Chang
2010-12-14 3:03 Re: Irish Online News
[not found] <20090427104117.GB29082@redhat.com>
2009-04-27 13:16 ` Re: Sheng Yang
2009-03-08 22:05 "-vga std" causes guest OS to crash (on disk io?) on a 1440x900 latpop Dylan Reid
2009-03-14 5:09 ` Dylan
2009-02-25 0:50 (unknown), Josh Borke
2009-02-25 0:58 ` Atsushi SAKAI
2009-01-10 21:53 (unknown) Ekin Meroğlu
2009-11-07 15:59 ` Bulent Abali
2009-11-07 16:36 ` Neil Aggarwal
2008-07-28 21:27 (unknown) Mohammed Gamal
2008-07-28 21:29 ` Mohammed Gamal
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