From: Eric Dumazet <edumazet@google.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: "Wei Wang" <weiwan@google.com>,
"Magnus Karlsson" <magnus.karlsson@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
"Network Development" <netdev@vger.kernel.org>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Hannes Frederic Sowa" <hannes@stressinduktion.org>,
"Felix Fietkau" <nbd@nbd.name>,
"Björn Töpel" <bjorn.topel@intel.com>
Subject: Re: [RFC PATCH net-next 0/6] implement kthread based napi poll
Date: Fri, 25 Sep 2020 20:23:37 +0200 [thread overview]
Message-ID: <CANn89iKAaKnZb3+RdMkK+Lx+5BBs=0Lnzwhe_jkzP4A8qHFZTg@mail.gmail.com> (raw)
In-Reply-To: <20200925111627.047f5ed2@hermes.lan>
On Fri, Sep 25, 2020 at 8:16 PM Stephen Hemminger
<stephen@networkplumber.org> wrote:
>
> On Fri, 25 Sep 2020 10:15:25 -0700
> Wei Wang <weiwan@google.com> wrote:
>
> > > > In terms of performance, I ran tcp_rr tests with 1000 flows with
> > > > various request/response sizes, with RFS/RPS disabled, and compared
> > > > performance between softirq vs kthread. Host has 56 hyper threads and
> > > > 100Gbps nic.
>
> It would be good to similar tests on othere hardware. Not everyone has
> server class hardware. There are people running web servers on untuned
> servers over 10 years old; this may cause a regression there.
>
> Not to mention the slower CPU's in embedded systems. How would this
> impact OpenWrt or Android?
Most probably you won't notice a significant difference.
Switching to a kthread is quite cheap, since you have no MMU games to play with.
>
> Another potential problem is that if you run real time (SCH_FIFO)
> threads they have higher priority than kthread. So for that use
> case, moving networking to kthread would break them.
Sure, playing with FIFO threads is dangerous.
Note that our plan is still to have softirqs by default.
If an admin chose to use kthreads, it is its choice, not ours.
This is also why I very much prefer the kthread approach to the work
queue, since the work queue could not be fine tuned.
next prev parent reply other threads:[~2020-09-25 18:23 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 17:24 [RFC PATCH net-next 0/6] implement kthread based napi poll Wei Wang
2020-09-14 17:24 ` [RFC PATCH net-next 1/6] net: implement threaded-able napi poll loop support Wei Wang
2020-09-25 19:45 ` Hannes Frederic Sowa
2020-09-25 23:50 ` Wei Wang
2020-09-26 14:22 ` Hannes Frederic Sowa
2020-09-28 8:45 ` Paolo Abeni
2020-09-28 18:13 ` Wei Wang
2020-09-14 17:24 ` [RFC PATCH net-next 2/6] net: add sysfs attribute to control napi threaded mode Wei Wang
2020-09-14 17:24 ` [RFC PATCH net-next 3/6] net: extract napi poll functionality to __napi_poll() Wei Wang
2020-09-14 17:24 ` [RFC PATCH net-next 4/6] net: modify kthread handler to use __napi_poll() Wei Wang
2020-09-14 17:24 ` [RFC PATCH net-next 5/6] net: process RPS/RFS work in kthread context Wei Wang
2020-09-18 22:44 ` Wei Wang
2020-09-21 8:11 ` Eric Dumazet
2020-09-14 17:24 ` [RFC PATCH net-next 6/6] net: improve napi threaded config Wei Wang
2020-09-25 13:48 ` [RFC PATCH net-next 0/6] implement kthread based napi poll Magnus Karlsson
2020-09-25 17:15 ` Wei Wang
2020-09-25 17:30 ` Eric Dumazet
2020-09-25 18:16 ` Stephen Hemminger
2020-09-25 18:23 ` Eric Dumazet [this message]
2020-09-25 19:00 ` Stephen Hemminger
2020-09-25 19:06 ` Jakub Kicinski
2020-09-28 14:07 ` Magnus Karlsson
2020-09-28 17:43 ` Eric Dumazet
2020-09-28 18:15 ` Wei Wang
2020-09-29 19:19 ` Jakub Kicinski
2020-09-29 20:16 ` Wei Wang
2020-09-29 21:48 ` Jakub Kicinski
2020-09-30 8:23 ` David Laight
2020-09-30 8:58 ` Paolo Abeni
2020-09-30 15:58 ` Jakub Kicinski
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