From: Declan Doherty <declan.doherty@intel.com>
To: Thomas Monjalon <thomas@monjalon.net>,
Radu Nicolau <radu.nicolau@intel.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [RFC][PATCH 2/5] pci: allow shared device instances.
Date: Wed, 10 May 2017 11:52:45 +0100 [thread overview]
Message-ID: <1c20ee02-530f-a39a-47c5-15cc5ce1a973@intel.com> (raw)
In-Reply-To: <18252037.5gudFzihFo@xps>
Hey Thomas, I've been working on this with Radu, so see my take below
On 10/05/2017 11:28 AM, Thomas Monjalon wrote:
> 10/05/2017 12:11, Radu Nicolau:
>> Hi
>>
>>
>> On 5/10/2017 10:09 AM, Thomas Monjalon wrote:
>>> Hi,
>>>
>>> 09/05/2017 16:57, Radu Nicolau:
>>>> Updated PCI initialization code to allow devices to be shared across multiple PMDs.
>>>>
>>>> Signed-off-by: Radu Nicolau <radu.nicolau@intel.com>
>>> I was waiting the day when we have a device shared
>>> by two different interfaces.
>>> Note that some Mellanox and Chelsio devices already instantiate
>>> two ethdev ports per PCI device.
>>>
>>> Please explain your idea behind this "shared" flag.
>>> What is your exact need?
>>
>> Currently for each pci device a look-up into a list of PMDs is
>> performed, and when a match is found the system moves to the next
>> device. Having this flag will allow a PMD to inform the system that
>> there may be more matches, more PMDs that can be used for this
>> particular device.
>> There is a difference when comparing to the devices you mentioned above,
>> in this case the PMDs are totally different types, one network and one
>> cryptodev PMD for each IXGBE network card.
>
> Yes I know it is a lack in DPDK.
> Linux introduced MultiFunction Device in 2005:
> http://events.linuxfoundation.org/sites/events/files/slides/belloni-mfd-regmap-syscon_0.pdf
>
So at the most basic level the intention is to allow more than one
device of different types, in our case a net PMD and a crypto PMD, to be
instantiated on a single PCI bar, in essence to share the bar. I'm not
familiar with the approaches taken in the Mellanox and Chelsio devices
but I assume they are handled with the driver probe/create functions
independently from the EAL infrastructure?
For the initial proto-typing of this RFC we only implemented the
multi-device creation but I envisage that there will be a requirement
for sharing state between drivers, or at a minimum implementing locking
around shared resources, registers etc. And I would like to see this
done in a generic fashion that can me leverage by any driver and not
have each driver having to solve this independently.
>>> Do you think it is the best solution?
>>
>> We evaluated different approaches and this is what we settled on. It
>> might not be the best, if there are any suggestions of other ways to
>> achieve this I would be thankful.
I think this approach was sufficient to enable the RFC and kick off the
discussion, but it is not a fully featured solution and we wanted to get
community feedback before progressing to far along with a fully featured
solution.
>
> Please could you explain the other approaches you thought
> with pros and cons?
>
> Thanks
>
next prev parent reply other threads:[~2017-05-10 10:52 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-09 14:57 [dpdk-dev] [RFC][PATCH 0/5] cryptodev: Adding support for inline crypto processing of IPsec flows Radu Nicolau
2017-05-09 14:57 ` [dpdk-dev] [RFC][PATCH 1/5] cryptodev: Updated API to add suport for inline IPSec Radu Nicolau
2017-05-09 14:57 ` [dpdk-dev] [RFC][PATCH 2/5] pci: allow shared device instances Radu Nicolau
2017-05-10 9:09 ` Thomas Monjalon
2017-05-10 10:11 ` Radu Nicolau
2017-05-10 10:28 ` Thomas Monjalon
2017-05-10 10:47 ` Radu Nicolau
2017-05-10 10:52 ` Declan Doherty [this message]
2017-05-10 11:08 ` Jerin Jacob
2017-05-10 11:31 ` Declan Doherty
2017-05-10 12:18 ` Jerin Jacob
2017-05-10 11:37 ` Thomas Monjalon
2017-05-09 14:57 ` [dpdk-dev] [RFC][PATCH 3/5] mbuff: added inline IPSec flags and metadata Radu Nicolau
2017-05-09 14:57 ` [dpdk-dev] [RFC][PATCH 4/5] cryptodev: added new crypto PMD supporting inline IPSec for IXGBE Radu Nicolau
2017-05-09 14:57 ` [dpdk-dev] [RFC][PATCH 5/5] examples: updated IPSec sample app to support inline IPSec Radu Nicolau
2017-05-10 16:07 ` [dpdk-dev] [RFC][PATCH 0/5] cryptodev: Adding support for inline crypto processing of IPsec flows Boris Pismenny
2017-05-10 17:21 ` Declan Doherty
2017-05-11 5:27 ` Boris Pismenny
2017-05-11 9:05 ` Radu Nicolau
2017-05-16 21:46 ` Thomas Monjalon
2017-05-24 10:06 ` Declan Doherty
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