Re: [PATCH rfc 0/5] generic adaptive IRQ moderation library for I/O devices

[Or Gerlitz <gerlitz.or-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Tue, Feb 6, 2018 at 11:45 AM, Tal Gilboa <talgi-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> wrote:
> On 2/6/2018 11:34 AM, Sagi Grimberg wrote:
>>
>> Hi Tal,
>>
>>>> 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?
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