Re: random pkt generator PMD

[Yerden Zhumabekov <e_zhumabekov@sts.kz>]

On 15.06.2016 19:02, Neil Horman wrote:
> On Wed, Jun 15, 2016 at 03:43:56PM +0600, Yerden Zhumabekov wrote:
>> Hello everybody,
>>
>> DPDK already got a number of PMDs for various eth devices, it even has PMD
>> emulations for backends such as pcap, sw rings etc.
>>
>> I've been thinking about the idea of having PMD which would generate mbufs
>> on the fly in some randomized fashion. This would serve goals like, for
>> example:
>>
>> 1) running tests for applications with network processing capabilities
>> without additional software packet generators;
>> 2) making performance measurements with no hw inteference;
>> 3) ability to run without root privileges, --no-pci, --no-huge, for CI
>> build, so on.
>>
>> Maybe there's no such need, and these goals may be achieved by other means
>> and this idea is flawed? Any thoughts?
>>
> I think you already have a solution to this problem.  Linux/BSD have multiple
> user space packet generators that can dump thier output to a pcap format file,
> and dpdk has a pcap pmd that accepts a pcap file as input to send in packets.

Things that I don't like about the idea of using PCAP PMD:

1) the need to create additional files with additional scripts and keep 
those with your test suite;
2) the need to rewind pcap once you played it (fixable);
3) reading packets one-by-one, file operations which may lead to perf 
impact;
4) low variability among source packets.

Those are things which put me on idea of randomized packet generator 
PMD. Possible devargs could be:
1) id of a template, like "ipv4", "ipv6", "dot1q" etc;
2) size of mbuf payload;
3) array of tuples like (offset, size, value) with value being exact 
value or "rnd" keyword.