Re: [LSF/MM TOPIC][LSF/MM ATTEND] NAPI polling for block drivers

Sagi Grimberg
2017-01-17T15:45:53Z

> --
> [1]
> queue = b'nvme0q1'
> usecs : count distribution
> 0 -> 1 : 7310 |****************************************|
> 2 -> 3 : 11 | |
> 4 -> 7 : 10 | |
> 8 -> 15 : 20 | |
> 16 -> 31 : 0 | |
> 32 -> 63 : 0 | |
> 64 -> 127 : 1 | |
>
> [2]
> queue = b'nvme0q1'
> usecs : count distribution
> 0 -> 1 : 7309 |****************************************|
> 2 -> 3 : 14 | |
> 4 -> 7 : 7 | |
> 8 -> 15 : 17 | |
>

Rrr, email made the histograms look funky (tabs vs. spaces...)
The count is what's important anyways...

Just adding that I used an Intel P3500 nvme device.

> We can see that most of the time our latency is pretty good (<1ns) but with
> huge tail latencies (some 8-15 ns and even one in 32-63 ns).

Obviously is micro-seconds and not nano-seconds (I wish...)