Re: [dpdk-dev] [PATCH v3 00/11] Port XStats

[Kyle Larose <eomereadig@gmail.com>]

Stephen,

Ultimately the issue we are trying to solve is that there is no device
independent way to get any detailed statistics from NICs controlled by
DPDK. These statistics are quite useful, not just for diagnostics, but
for long term reporting. People using DPDK-based NFV products in a
production environment are not going to be happy that they cannot, for
example, see how the packet size bucket counters varied over time
using some sort of monitoring tool.

The only alternative I can see to providing an API within DPDK is to
build our own abstraction layer triggered off the driver name/pci
ids/etc. I expect other people would end up doing this as well. This
seems like a waste of effort when an abstraction layer already exists
within DPDK.

So, let's consider solving the problem within DPDK. One option is to
use well-defined names for a given xstat that has the same semantics
across NICs, while continuing to allow NICs to expose any stats that
don't fall into this category.

Another option is to provide an API with a well-defined set of stats,
perhaps using an enum. In order for a stat to be added to this list,
it needs to be part of a standard (such as
http://tools.ietf.org/html/rfc2819).

Does anybody else see the need for something like this? We're more
than willing to do the work. We'd like to make sure we have the right
API, though.

Thanks,

Kyle

On Wed, Oct 28, 2015 at 8:55 PM, Tom Crugnale <tcrugnale@sandvine.com> wrote:
> I understand.  Is this the reason that that strings were used to identify the xstat types?  An enum type would be much more efficient instead of doing string copies when retrieving the stats, but the number of enum entries would quickly grow out of control as device specific stats were added.
>
> In this case, I'm actually referring to the stats that are common to all NICs.  For example, for the received fragmented packets counter, there are three strings that identify this value: rx_fragment_packets (igb), rx_fragment_errors (ixgbe), rx_fragmented_packets (i40e).
> I was thinking of making those names consistent.  Perhaps the reason why they were different in the first place is that each of the device datasheets refers to these exact names.
>
> Tom
>
> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Wednesday, October 28, 2015 5:32 PM
> To: Tom Crugnale
> Cc: Harry van Haaren; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v3 00/11] Port XStats
>
> On Wed, 28 Oct 2015 17:35:09 +0000
> Tom Crugnale <tcrugnale@sandvine.com> wrote:
>
>> Hi Harry,
>>
>> We are planning on using the xstats API for periodic stats collection through a polling thread.  This would be done in a generic NIC agnostic manner, which would require that the xstats identifiers have consistent naming amongst all of the NIC types.  It would likely be polled several times per second and would only gather a subset of all available xstats types.
>>
>> I have reviewed your patches and am interested in providing some API enhancements and bugfixes.  Are you willing to provide feedback on such changes?
>>
>> Thank you,
>> Tom
>
> The whole point of xstats is to allow device specific statistics.
> Consistent use of names is good from a user interface point of view, but probably not a hard requirement.
>