From: Eric Dumazet <edumazet@google.com>
To: Paolo Abeni <pabeni@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"David S. Miller" <davem@davemloft.net>,
Steven Rostedt <rostedt@goodmis.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Hannes Frederic Sowa <hannes@stressinduktion.org>,
netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH 4/5] netdev: implement infrastructure for threadable napi irq
Date: Wed, 15 Jun 2016 07:17:37 -0700 [thread overview]
Message-ID: <CANn89i+EJMHeMN8=e12hoT1Jv8cCBDXeexTBdsd9hU2G=HpGZA@mail.gmail.com> (raw)
In-Reply-To: <f5e431e8336f80d0e6f6b4c40c81a373db6d6052.1465996447.git.pabeni@redhat.com>
On Wed, Jun 15, 2016 at 6:42 AM, Paolo Abeni <pabeni@redhat.com> wrote:
> This commit adds the infrastructure needed for threadable
> rx interrupt. A reference to the irq thread is used to
> mark the threaded irq mode.
> In threaded mode the poll loop is invoked directly from
> __napi_schedule().
> napi drivers which want to support threadable irq interrupts
> must provide an irq mode change handler which actually set
> napi->thread and register it after requesting the irq.
>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> ---
> include/linux/netdevice.h | 4 ++++
> net/core/dev.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 63 insertions(+)
>
I really appreciate the effort, but as I already said this is not going to work.
Many NIC have 2 NAPI contexts per queue, one for TX, one for RX.
Relying on CFS to switch from the two 'threads' you need in the one
vCPU case will add latencies that your 'pure throughput UDP flood' is
not able to detect.
I was waiting a fix from Andy Lutomirski to be merged before sending
my ksoftirqd fix, which will work and wont bring kernel bloat.
next prev parent reply other threads:[~2016-06-15 14:17 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-15 13:42 [PATCH 0/5] genirq: threadable IRQ support Paolo Abeni
2016-06-15 13:42 ` [PATCH 1/5] genirq: implement support for runtime switch to threaded irqs Paolo Abeni
2016-06-15 14:50 ` kbuild test robot
2016-06-15 13:42 ` [PATCH 2/5] genirq: add flags for controlling the default threaded irq behavior Paolo Abeni
2016-06-15 13:42 ` [PATCH 3/5] sched/preempt: cond_resched_softirq() must check for softirq Paolo Abeni
2016-06-15 13:48 ` Peter Zijlstra
2016-06-15 14:00 ` Paolo Abeni
2016-06-15 13:42 ` [PATCH 4/5] netdev: implement infrastructure for threadable napi irq Paolo Abeni
2016-06-15 14:12 ` kbuild test robot
2016-06-15 14:17 ` Eric Dumazet [this message]
2016-06-15 14:21 ` Eric Dumazet
2016-06-15 16:42 ` Paolo Abeni
2016-06-15 17:04 ` Eric Dumazet
2016-06-16 10:39 ` Paolo Abeni
2016-06-16 11:19 ` Eric Dumazet
2016-06-16 12:03 ` Paolo Abeni
2016-06-16 16:55 ` Eric Dumazet
2016-06-15 13:42 ` [PATCH 5/5] ixgbe: add support for threadable rx irq Paolo Abeni
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