linux-kernel - Re: [net-next PATCH v2 0/8] Add busy poll support for epoll

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Message-ID: <CANn89i+ygBw_tHcAaDJhHJqvOYAqkHJ3nnokByUQWVeXv0MDfA@mail.gmail.com>
Date:   Thu, 23 Mar 2017 15:49:08 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Netdev <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Samudrala, Sridhar" <sridhar.samudrala@...el.com>,
        David Miller <davem@...emloft.net>, linux-api@...r.kernel.org
Subject: Re: [net-next PATCH v2 0/8] Add busy poll support for epoll

On Thu, Mar 23, 2017 at 3:38 PM, Alexander Duyck
<alexander.duyck@...il.com> wrote:
> On Thu, Mar 23, 2017 at 3:07 PM, Alexei Starovoitov

>> it all sounds awesome, but i cannot quite visualize the impact.
>> Can you post some sample code/minibenchmark and numbers before/after?
>>
>> Thanks!
>>
>
> Anything specific you are looking for?  I can probably work with our
> team internally to setup the benchmark in the next day or so.
>
> I've been doing most of my benchmarking at my desk with sockperf with
> just one thread and multiple sockets and seeing some modest savings
> with my round trip times dropping from something like 18 microseconds
> on average to 8 microseconds for ping-pong tests.

Same reduction for me, on 1000/1000 bytes RPC.

26 usec -> 16 usec  per transaction

(If you use sockperf, beware that it displays half round trips)

Also note that the gains also depends on how the interrupt mitigation
parameters are set.