[dpdk-dev] [PATCH 0/3] null driver improvements for testability

Paul Atkins patkins at brocade.com
Tue Feb 23 16:24:35 CET 2016



On 23/02/16 15:21, Bruce Richardson wrote:
> On Thu, Feb 18, 2016 at 12:19:58PM +0000, Paul Atkins wrote:
>>
>> On 17/02/16 17:23, Bruce Richardson wrote:
>>> On Fri, Jan 29, 2016 at 04:47:58PM +0000, Paul Atkins wrote:
>>>> Hi Thomas,
>>>>
>>>> On 29/01/16 16:31, Thomas Monjalon wrote:
>>>>> Hi Paul,
>>>>>
>>>>> 2016-01-29 16:18, Paul Atkins:
>>>>>> This patchset adds functionality to the null driver help when testing
>>>>>> a dataplane that uses dpdk.  The idea is that the the dataplane can
>>>>>> have multiple null interfaces attached, and each of theses can be
>>>>>> assigned a mac address. Packets can then be injected into the null
>>>>>> drivers by adding them to a ring, giving the application complete
>>>>>> control of the packets that arrive.  Packets that are sent by a null
>>>>>> driver can be stored on a ring, where the application can pick them up
>>>>>> and verify it is what was expected.  To allow the application to know
>>>>>> when packets have been pulled of the rx ring, counters of the number of
>>>>>> times an rx poll has been made are kept, and these can be retrieved via
>>>>>> the existing APIs.
>>>>> I have not read your code, just read this description.
>>>>> It sounds like being a ring PMD. Have you already checked it?
>>>>> https://urldefense.proofpoint.com/v2/url?u=http-3A__dpdk.org_browse_dpdk_tree_drivers_net_ring_rte-5Feth-5Fring.c&d=CwICAg&c=IL_XqQWOjubgfqINi2jTzg&r=45ezphVDEm8OnEpH-fLWdXvR3RneLhhNZRDLQRgR6LY&m=wJLO24XFe_B0nZve6mkvocCt7fQWo3PULCTWxrC8rZk&s=bIWycJrY-PYgzkQsBeRfkl8JCHFcxRAHhHDrqRSzHYs&e=
>>>> I hadn't seen the ring PMD. I will have a look at it and see if I can make
>>>> it do what i need.
>>>>
>>>> thanks,
>>>> Paul
>>> Hi Paul,
>>>
>>> any update on this. Your patches are still showing as pending in patchwork, but
>>> if ring pmd is more what need, we can set these patches aside as unneeded, and
>>> remove them from the patchwork merge backlog.
>> Hi Bruce,
>>
>> Sorry for the delay.  The patchset adds 3 things: assigning a mac addr to
>> the null pmd, adding the rings to the null pmd and adding xstats for how
>> many times the null pmd has been polled.  I could move to using the ring
>> pmd, but I would still need the other 2 parts (mac addr and stats).  It
>> seems like the ring pmd shouldn't really have these two extra things added,
>> but i could do that if it that is preferred over what is in the current
>> patchset.
>>
> Adding a mac address to be reported by the ring PMD should not be a problem.
> Having a stat that tracks polls might be depending on how it is done - if it
> uses an atomic, as in this patchset, it would problematic as it would add a
> severe performance hit for the SP/SC ring case. However, you could get around
> that by copying what is already done in the PMD for tracking packet counts.
>
> Overall, though, it seems that it might be worthwhile doing the work to extend
> the ring pmd rather than turning the null pmd into a second ring one.

Ok, I will make those changes and resubmit - you can mark the current 
patches as unneeded.

thanks,
Paul

>
> Regards,
> /Bruce



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