From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
sridhar.samudrala@intel.com, edumazet@google.com,
davem@davemloft.net, linux-api@vger.kernel.org
Subject: Re: [net-next PATCH v2 0/8] Add busy poll support for epoll
Date: Thu, 23 Mar 2017 15:07:23 -0700 [thread overview]
Message-ID: <20170323220721.GA62356@ast-mbp.thefacebook.com> (raw)
In-Reply-To: <20170323211820.12615.88907.stgit@localhost.localdomain>
On Thu, Mar 23, 2017 at 02:36:29PM -0700, Alexander Duyck wrote:
> This is my second pass at trying to add support for busy polling when using
> epoll. It is pretty much a full rewrite as I have made serious changes to
> most of the patches.
>
> In the v1 series I had submitted we only allowed epoll to make use of busy
> poll when all NAPI IDs were the same. I gave this some more thought and
> after making several other changes based on feedback from Eric Dumazet I
> decided to try changing the main concept a bit and instead we will now
> attempt to busy poll on the NAPI ID of the last socket added to the ready
> list. By doing it this way we are able to take advantage of the changes
> Eric has already made so that we get woken up by the softirq, we then pull
> packets via busy poll, and will return to the softirq until we are woken up
> and a new socket has been added to the ready list.
>
> Most of the changes in this set authored by me are meant to be cleanup or
> fixes for various things. For example, I am trying to make it so that we
> don't perform hash look-ups for the NAPI instance when we are only working
> with sender_cpu and the like.
>
> The most complicated change of the set is probably the clean-ups for the
> timeout. I realized that the timeout could potentially get into a state
> where it would never timeout if the local_clock() was approaching a
> rollover and the added busy poll usecs interval would be enough to roll it
> over. Because we were shifting the value you would never be able to get
> time_after to actually trigger.
>
> At the heart of this set is the last 3 patches which enable epoll support
> and add support for obtaining the NAPI ID of a given socket. With these
> It becomes possible for an application to make use of epoll and get optimal
> busy poll utilization by stacking multiple sockets with the same NAPI ID on
> the same epoll context.
it all sounds awesome, but i cannot quite visualize the impact.
Can you post some sample code/minibenchmark and numbers before/after?
Thanks!
next prev parent reply other threads:[~2017-03-23 22:07 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-23 21:36 [net-next PATCH v2 0/8] Add busy poll support for epoll Alexander Duyck
[not found] ` <20170323211820.12615.88907.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-03-23 21:36 ` [net-next PATCH v2 1/8] net: Busy polling should ignore sender CPUs Alexander Duyck
2017-03-23 22:05 ` Eric Dumazet
2017-03-23 21:36 ` [net-next PATCH v2 2/8] tcp: Record Rx hash and NAPI ID in tcp_child_process Alexander Duyck
[not found] ` <20170323213644.12615.27158.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-03-24 1:00 ` Eric Dumazet
2017-03-23 21:36 ` [net-next PATCH v2 3/8] net: Only define skb_mark_napi_id in one spot instead of two Alexander Duyck
[not found] ` <20170323213651.12615.62895.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-03-24 1:02 ` Eric Dumazet
2017-03-23 21:37 ` [net-next PATCH v2 4/8] net: Change return type of sk_busy_loop from bool to void Alexander Duyck
[not found] ` <20170323213715.12615.49246.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-03-24 1:02 ` Eric Dumazet
2017-03-23 21:37 ` [net-next PATCH v2 5/8] net: Track start of busy loop instead of when it should end Alexander Duyck
2017-03-24 1:24 ` Eric Dumazet
2017-03-24 3:42 ` Alexander Duyck
[not found] ` <CAKgT0Ue+UFOAhwxN-EOjWYZa9YZc2QaT5gvoLap70COs0rF7NA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-03-24 4:27 ` Eric Dumazet
2017-03-24 4:38 ` Eric Dumazet
2017-03-24 5:55 ` Alexander Duyck
[not found] ` <CAKgT0UfQPLqHtZ_SjanbLoG6t5f36C4nsORuw6yjLT0xZrEoEQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-03-24 11:16 ` Eric Dumazet
[not found] ` <1490354210.9687.44.camel-XN9IlZ5yJG9HTL0Zs8A6p+yfmBU6pStAUsxypvmhUTTZJqsBc5GL+g@public.gmane.org>
2017-03-24 15:48 ` Alexander Duyck
2017-03-23 21:37 ` [net-next PATCH v2 6/8] net: Commonize busy polling code to focus on napi_id instead of socket Alexander Duyck
[not found] ` <20170323213749.12615.38165.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-03-23 22:25 ` Eric Dumazet
2017-03-23 21:37 ` [net-next PATCH v2 7/8] epoll: Add busy poll support to epoll with socket fds Alexander Duyck
2017-03-23 21:38 ` [net-next PATCH v2 8/8] net: Introduce SO_INCOMING_NAPI_ID Alexander Duyck
[not found] ` <20170323213802.12615.58216.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-03-23 22:22 ` Eric Dumazet
2017-03-23 22:43 ` Andy Lutomirski
2017-03-24 0:58 ` Alexander Duyck
[not found] ` <CAKgT0UcHJVycQ3+h09L2Ph=TVncqHPJ6dZpicUgBo7TaFTN7yw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-03-24 4:47 ` Andy Lutomirski
2017-03-24 5:07 ` Eric Dumazet
2017-03-23 22:07 ` Alexei Starovoitov [this message]
[not found] ` <20170323220721.GA62356-+o4/htvd0TDFYCXBM6kdu7fOX0fSgVTm@public.gmane.org>
2017-03-23 22:38 ` [net-next PATCH v2 0/8] Add busy poll support for epoll Alexander Duyck
[not found] ` <CAKgT0Uctdf4N-w72EY8T5Zfw=QCSCgAesXdgOh-HUYdD=Aq9AA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-03-23 22:49 ` Eric Dumazet
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