[dpdk-dev] [PATCH v3 02/12] eal/bus: introduce bus abstraction
Shreyansh Jain
shreyansh.jain at nxp.com
Thu Dec 22 06:52:54 CET 2016
On Thursday 22 December 2016 10:42 AM, Shreyansh Jain wrote:
> On Thursday 22 December 2016 05:03 AM, Stephen Hemminger wrote:
>> On Wed, 21 Dec 2016 16:38:42 +0100
>> Jan Blunck <jblunck at infradead.org> wrote:
>>
>>> On Tue, Dec 20, 2016 at 6:11 PM, Stephen Hemminger
>>> <stephen at networkplumber.org> wrote:
>>>> On Tue, 20 Dec 2016 14:17:14 +0100
>>>> Jan Blunck <jblunck at infradead.org> wrote:
>>>>
>>>>> On Fri, Dec 16, 2016 at 2:10 PM, Shreyansh Jain
>>>>> <shreyansh.jain at nxp.com> wrote:
>>>>>> This patch introduces the rte_bus abstraction for devices and
>>>>>> drivers in
>>>>>> EAL framework. The model is:
>>>>>> - One or more buses are connected to a CPU (or core)
>>>>>> - One or more devices are conneted to a Bus
>>>>>> - Drivers are running instances which manage one or more devices
>>>>>> - Bus is responsible for identifying devices (and interrupt
>>>>>> propogation)
>>>>>> - Driver is responsible for initializing the device
>>>>>>
>>>>>> This patch adds a 'rte_bus' class which rte_driver and rte_device
>>>>>> refer.
>>>>>> This way, each device (rte_xxx_device) would have reference to the
>>>>>> bus
>>>>>> it is based on. As well as, each driver (rte_xxx_driver) would
>>>>>> have link
>>>>>> to the bus and devices on it for servicing.
>>>>>>
>>>>>> __ rte_bus_list
>>>>>> /
>>>>>> +----------'---+
>>>>>> |rte_bus |
>>>>>> | driver_list------> List of rte_bus specific
>>>>>> | device_list---- devices
>>>>>> | | `-> List of rte_bus associated
>>>>>> | | drivers
>>>>>> +--|------|----+
>>>>>> _________/ \_________
>>>>>> +--------/----+ +-\---------------+
>>>>>> |rte_device | |rte_driver |
>>>>>> | rte_bus | | rte_bus |
>>>>>> | rte_driver | | ... |
>>>>>> | ... | +---------...-----+
>>>>>> | | |||
>>>>>> +---||--------+ |||
>>>>>> || |||
>>>>>> | \ \\\
>>>>>> | \_____________ \\\
>>>>>> | \ |||
>>>>>> +------|---------+ +----|----------+ |||
>>>>>> |rte_pci_device | |rte_xxx_device | |||
>>>>>> | .... | | .... | |||
>>>>>> +----------------+ +---------------+ / | \
>>>>>> / | \
>>>>>> _____________________/ / \
>>>>>> / ___/ \
>>>>>> +-------------'--+ +------------'---+
>>>>>> +--'------------+
>>>>>> |rte_pci_driver | |rte_vdev_driver |
>>>>>> |rte_xxx_driver |
>>>>>> | .... | | .... | |
>>>>>> .... |
>>>>>> +----------------+ +----------------+
>>>>>> +---------------+
>>>>>>
>>>>>> This patch only enables the bus references on rte_driver and
>>>>>> rte_driver.
>>>>>> EAL wide global device and driver list continue to exist until an
>>>>>> instance
>>>>>> of bus is added in subsequent patches.
>>>>>>
>>>>>> This patch also introduces RTE_REGISTER_BUS macro on the lines of
>>>>>> RTE_PMD_REGISTER_XXX. Key difference is that the constructor
>>>>>> priority has
>>>>>> been explicitly set to 101 so as to execute bus registration
>>>>>> before PMD.
>>>>>>
>>>>>> Signed-off-by: Shreyansh Jain <shreyansh.jain at nxp.com>
>>>>>>
>>>>
>>>> Ok, but let's keep this as bus type not bus. It gets really hard and
>>>> complex
>>>> to enumerate all layers of PCI bus and bridges.
>>>
>>> As far as I understand it this isn't the intention to replicate the
>>> hierarchy of buses we have in the kernel. The PCI bus in this case
>>> becomes a list of PCI devices.
>>
>> One of the motivations seems to be "lets be able to handle lots of
>> devices",
>> but the current model with an array of ports is not going to scale
>> well for that.
>>
>> It is time to make rte_eth_devices into rb-tree and get rid of
>> MAX_PORTS config
>> option.
>>
>
> That is a nice idea. Probably once we get the EAL compatible for 'lots
> of devices', this would be next good change.
Just out of curiosity - I think only need here is to do away with
'MAX_PORTS'. There is no need for a 'fast' lookup of ports as this part
wouldn't be part of datapath. Am I wrong in assuming this?
>
> -
> Shreyansh
>
>
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