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List: dragonfly-users
Subject: Re: Study of nginx-1.9.12 performance/latency on DragonFlyBSD-g67a73.
From: Sepherosa Ziehau <sepherosa () gmail ! com>
Date: 2016-05-10 13:00:01
Message-ID: CAMOc5cxvDQ5g8P9pWfNw2281fYfKufANBCjkYFiR5d9_ogtPsg () mail ! gmail ! com
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On Tue, May 10, 2016 at 1:40 AM, Matthew Dillon <dillon@backplane.com> wrote:
> Very interesting results. I'm not surprised that lowering the poll rate
> improves the results, that's an artifact of scheduling larger batches (as
> long as the ring buffer doesn't fill up completely). It's true for process
> scheduling too but usually at the cost of losing interactive responsiveness
> which is why schedulers implement hybrid mechanics.
>
> I was surprised that the chipset-rate-limited interrupt mode was so bad
> compared to the polling. I would have expected it to approach polling
> effectiveness at the same frequency. But it clearly doesn't (at least not
> at ~7000-8000hz). If you can program it, could you try a lower chipset
> interrupt rate at 1000hz and 4000hz?
Here is the new tables for interrupt and polling comparison at same frequency:
Requests/s
intr | poll
----------+----------
7000hz 116961 | 140580
4000hz 143505 | 142862
1000hz 143391 | 144807
Average Latency
intr | poll
----------+----------
7000hz 64.14ms | 54.25ms
4000hz 53.08ms | 52.87ms
1000hz 51.85ms | 51.20ms
Latency Stdev
intr | poll
----------+----------
7000hz 150.30ms | 21.68ms
4000hz 20.99ms | 19.16ms
1000hz 16.53ms | 13.96ms
Interrupt @4000hz and @1000hz have almost same performance and latency
as the polling(4).
Thanks,
sephe
--
Tomorrow Will Never Die
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