Re: [dpdk-dev] [PATCH v7 5/6] lib: added new library for latency stats

[Olivier MATZ <olivier.matz@6wind.com>]

On Wed, 18 Jan 2017 21:11:28 +0100, Olivier Matz
<olivier.matz@6wind.com> wrote:
> Hi guys,
> 
> On Tue, 17 Jan 2017 21:55:16 +0530, Jerin Jacob
> > Oliver,
> > 
> > Could you please suggest how to proceed further?
> >   
> 
> Sorry for the lack of response. I know people are waiting for
> me, but these days I have too many things to do at the same time, and
> it's difficult to find time.
> 
> In few words (I'll provide more detailed answers to the thread by
> friday): I expected to post the mbuf rework patchset for this release,
> which includes the structure changes (Jerin's patch for arm access,
> timestamp, port, nb_segs, refcnt changes). But the patchset is clearly
> not ready yet, it needs a rebase, and it lacks test.
> 
> Jerin, I know that you submitted your patch a long time ago, and I'm
> the only one to blame, please do not see any vendor preference in it.
> 
> I'll check friday what's the effective state of the patchset in my
> workspace. If I can extract a minimal patch that only change the
> structure, I'll send it for discussion. But from what I remember, the
> mbuf structure rework depends on changing the way we access the
> refcnt, so it can be moved to the 2nd cache line.
> 
> If that's not possible, I'll try propose some alternatives.

I just posted a mbuf RFC patchset [1]. I think it contains most
things that were mentioned on the ML. As checked with Thomas, it's too
late to have it included in 17.02.

I'll tend to agree with John that having the timestamp in the mbuf for
latency is not an ABI break, since it is added at the end of the
structure. So I won't oppose to add this field in the mbuf structure
for the release.

The mbuf rearm patch was not forgotten, but it took clearly too long to
be integrated. With the benefit of hindsight, it should have been
pushed without waiting the mbuf rework. Again, apologies for that, I
understand it's quite frustrating.

Anyway, tests or comments on my RFC patchset are welcome, so we can
integrate it at the beginning of the 17.05 cycle.

Regards,
Olivier

[1] http://dpdk.org/ml/archives/dev/2017-January/056187.html