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From: Stefan Hajnoczi <stefanha@gmail.com>
To: David Marchand <david.marchand@6wind.com>
Cc: Henning Schild <henning.schild@siemens.com>,
	Olivier MATZ <olivier.matz@6wind.com>, kvm <kvm@vger.kernel.org>,
	qemu-devel <qemu-devel@nongnu.org>,
	Linux Virtualization <virtualization@lists.linux-foundation.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Vincent JARDIN <vincent.jardin@6wind.com>,
	"thomas.monjalon@6wind.com" <thomas.monjalon@6wind.com>
Subject: Re: [Qemu-devel] Why I advise against using ivshmem
Date: Wed, 18 Jun 2014 18:51:20 +0800	[thread overview]
Message-ID: <20140618105120.GI14030@stefanha-thinkpad.redhat.com> (raw)
In-Reply-To: <53A00464.8090609@6wind.com>


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On Tue, Jun 17, 2014 at 11:03:32AM +0200, David Marchand wrote:
> On 06/17/2014 04:54 AM, Stefan Hajnoczi wrote:
> >ivshmem has a performance disadvantage for guest-to-host
> >communication.  Since the shared memory is exposed as PCI BARs, the
> >guest has to memcpy into the shared memory.
> >
> >vhost-user can access guest memory directly and avoid the copy inside the guest.
> 
> Actually, you can avoid this memory copy using frameworks like DPDK.

I guess it's careful to allocate all packets in the mmapped BAR?

That's fine if you can modify applications but doesn't work for
unmodified applications using regular networking APIs.

Stefan

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  parent reply	other threads:[~2014-06-18 10:51 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20140610184818.2e490419@nbschild1>
2014-06-10 22:15 ` Using virtio for inter-VM communication Vincent JARDIN
2014-06-12  2:27 ` Rusty Russell
2014-06-12  5:32   ` Jan Kiszka
     [not found]   ` <53993B7B.7010404@siemens.com>
2014-06-13  0:47     ` Rusty Russell
2014-06-13  6:23       ` Jan Kiszka
2014-06-13  8:45         ` Paolo Bonzini
2014-06-15  6:20           ` Jan Kiszka
     [not found]           ` <539D3B35.2010706@web.de>
2014-06-17  5:24             ` Paolo Bonzini
     [not found]             ` <539FD124.6050007@redhat.com>
2014-06-17  5:57               ` Jan Kiszka
     [not found] ` <53978375.6090707@6wind.com>
2014-06-12  6:48   ` Markus Armbruster
     [not found]   ` <87ppie1v4r.fsf@blackfin.pond.sub.org>
2014-06-12  7:44     ` Henning Schild
2014-06-12  9:31       ` Vincent JARDIN
2014-06-12 12:55       ` [Qemu-devel] " Markus Armbruster
2014-06-12 14:40       ` Why I advise against using ivshmem (was: [Qemu-devel] Using virtio for inter-VM communication) Markus Armbruster
     [not found]       ` <87vbs6qjhj.fsf_-_@blackfin.pond.sub.org>
2014-06-12 16:02         ` Why I advise against using ivshmem Vincent JARDIN
     [not found]         ` <5399CF09.8030803@6wind.com>
2014-06-12 16:54           ` Paolo Bonzini
2014-06-13  8:46           ` [Qemu-devel] " Markus Armbruster
2014-06-13  9:26             ` Vincent JARDIN
2014-06-13  9:31               ` Jobin Raju George
2014-06-13  9:48               ` Olivier MATZ
2014-06-13 10:09               ` Paolo Bonzini
2014-06-13 13:41                 ` Vincent JARDIN
     [not found]                 ` <539AFF7C.7090702@6wind.com>
2014-06-13 14:10                   ` Paolo Bonzini
2014-06-14 18:01                     ` Vincent JARDIN
2014-06-17  2:54                     ` Stefan Hajnoczi
2014-06-17  9:03                       ` David Marchand
     [not found]                       ` <53A00464.8090609@6wind.com>
2014-06-17  9:44                         ` Paolo Bonzini
2014-06-18 10:48                           ` Stefan Hajnoczi
2014-06-18 14:57                             ` David Marchand
2014-06-18 15:01                             ` Andreas Färber
     [not found]                             ` <53A1A8BE.3000801@6wind.com>
2014-06-18 15:10                               ` Paolo Bonzini
2014-06-21  9:34                               ` Stefan Hajnoczi
2014-06-26 20:02                                 ` Cam Macdonell
     [not found]                             ` <53A1A9D9.6010908@suse.de>
2014-06-19  8:25                               ` David Marchand
2014-06-30 11:10                             ` Markus Armbruster
2014-06-18 10:51                         ` Stefan Hajnoczi [this message]
2014-06-18 14:58                           ` David Marchand
2014-06-13  9:29             ` Jobin Raju George

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