netdev - Re: [net-next PATCH v3 7/8] epoll: Add busy poll support to epoll with socket fds.

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Message-ID: <1490412818.24891.9.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Fri, 24 Mar 2017 20:33:38 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        sridhar.samudrala@...el.com, edumazet@...gle.com,
        davem@...emloft.net, linux-api@...r.kernel.org
Subject: Re: [net-next PATCH v3 7/8] epoll: Add busy poll support to epoll
 with socket fds.

On Fri, 2017-03-24 at 10:08 -0700, Alexander Duyck wrote:
> From: Sridhar Samudrala <sridhar.samudrala@...el.com>
> 
> This patch adds busy poll support to epoll. The implementation is meant to
> be opportunistic in that it will take the NAPI ID from the last socket
> that is added to the ready list that contains a valid NAPI ID and it will
> use that for busy polling until the ready list goes empty.  Once the ready
> list goes empty the NAPI ID is reset and busy polling is disabled until a
> new socket is added to the ready list.
> 
> In addition when we insert a new socket into the epoll we record the NAPI
> ID and assume we are going to receive events on it.  If that doesn't occur
> it will be evicted as the active NAPI ID and we will resume normal
> behavior.
> 
> An application can use SO_INCOMING_CPU or SO_REUSEPORT_ATTACH_C/EBPF socket
> options to spread the incoming connections to specific worker threads
> based on the incoming queue. This enables epoll for each worker thread
> to have only sockets that receive packets from a single queue. So when an
> application calls epoll_wait() and there are no events available to report,
> busy polling is done on the associated queue to pull the packets.
> 
> Signed-off-by: Sridhar Samudrala <sridhar.samudrala@...el.com>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
> ---
>  fs/eventpoll.c |   93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 93 insertions(+)

Acked-by: Eric Dumazet <edumazet@...gle.com>