On Tue, Feb 6, 2018 at 11:45 AM, Tal Gilboa [off-list ref] wrote:

On 2/6/2018 11:34 AM, Sagi Grimberg wrote:

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Hi Tal,

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I think Tal has idea/s on how the existing library can be changed to
support more modes/models

What I was thinking is allowing DIM algorithm to disregard data which is
0. Currently if bytes == 0 we return "SAME" immediately. We can change it to
simply move to the packets check (which may be renamed to "completions").
This way you could use DIM while only optimizing to (P1) high packet rate
and (P2) low interrupt rate.

That was exactly where I started from. But unfortunately it did not work
well :(

 From my experiments, the moderation was all over the place failing to
converge. At least the workloads that I've tested with, it was more
successful to have a stricter step policy and pulling towards latency
if we are consistently catching single completion per event.

I'm not an expert here at all, but at this point, based on my attempts
so far, I'm not convinced the current net_dim scheme could work.

I do believe we can make it work. I see your addition of the cpe part to
stats compare. Might not be a bad idea for networking devices. Overall, it
seems to me like this would be a private case of the general DIM
optimization, since it doesn't need to account for aggregation, for
instance, which breaks the "more packets == more data" ratio.

Did U2 came to agreement/lead on how to re-use the upstream library
for the matter Sagi is pushing for?