From: Mike Galbraith <efault@gmx.de>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>
Cc: Eric Dumazet <edumazet@google.com>,
Dmitry Safonov <dima@arista.com>,
Frederic Weisbecker <frederic@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Frederic Weisbecker <fweisbec@gmail.com>,
Hannes Frederic Sowa <hannes@stressinduktion.org>,
Ingo Molnar <mingo@kernel.org>,
"Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>,
Paolo Abeni <pabeni@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Radu Rendec <rrendec@arista.com>, Rik van Riel <riel@redhat.com>,
Stanislaw Gruszka <sgruszka@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Wanpeng Li <wanpeng.li@hotmail.com>
Subject: Re: [RFC 1/2] softirq: Defer net rx/tx processing to ksoftirqd context
Date: Fri, 12 Jan 2018 18:44:09 +0100 [thread overview]
Message-ID: <1515779049.21898.23.camel@gmx.de> (raw)
In-Reply-To: <CA+55aFygPtKM0fOGu1HNdZ9TCgk5hJ3r78fX03KYUT=0npPiEw@mail.gmail.com>
On Fri, 2018-01-12 at 09:26 -0800, Linus Torvalds wrote:
> On Fri, Jan 12, 2018 at 2:13 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Fri, Jan 12, 2018 at 06:23:08AM +0100, Mike Galbraith wrote:
> >>
> >> How would that be better than what RT used to do, and I still do for my
> >> RT kernels via boot option, namely split ksoftirqd into per-softirq
> >> threads.
> >
> > Since we mention it; one of the problems RT has is that all RX is
> > through a single softirq context, which generates a priority inversion
> > between devices.
>
> Oh, yes, that is complete and utter shit. Not acceptable at all.
>
> As mentioned, it really would need to be per-cpu _and_ per-softirq.
>
> Which is why I thought workqueues might be the thing. Whatever RT is
> doing is apparently just pure and utter garbage.
Nah, a misunderstanding happened. RT that still offers full threading
creates per-softirq threads per cpu. The regular trees split ksoftirqd
into only two threads per cpu, one processes timer/hrtimer softriqs,
the other processes the rest.
-Mike
next prev parent reply other threads:[~2018-01-12 17:45 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-09 13:36 [RFC 0/2] Net softirq deferring to ksoftirqd Dmitry Safonov
2018-01-09 13:36 ` [RFC 1/2] softirq: Defer net rx/tx processing to ksoftirqd context Dmitry Safonov
2018-01-09 16:03 ` Frederic Weisbecker
2018-01-10 21:20 ` Dmitry Safonov
2018-01-09 18:02 ` Eric Dumazet
2018-01-10 21:48 ` Dmitry Safonov
2018-01-11 2:13 ` Linus Torvalds
2018-01-11 3:22 ` Frederic Weisbecker
2018-01-11 4:19 ` Linus Torvalds
2018-01-11 4:44 ` Frederic Weisbecker
2018-01-11 14:31 ` Dmitry Safonov
2018-01-11 16:20 ` Eric Dumazet
2018-01-11 16:32 ` Peter Zijlstra
2018-01-11 16:38 ` David Miller
2018-01-11 16:43 ` Peter Zijlstra
2018-01-11 18:48 ` Linus Torvalds
2018-01-11 19:15 ` Eric Dumazet
2018-01-11 19:43 ` Linus Torvalds
2018-01-11 19:48 ` Eric Dumazet
2018-01-11 20:03 ` Linus Torvalds
2018-01-11 20:16 ` Eric Dumazet
2018-01-11 20:22 ` Linus Torvalds
2018-01-11 20:34 ` Dmitry Safonov
2018-01-11 20:37 ` Eric Dumazet
2018-01-11 20:40 ` Linus Torvalds
2018-01-11 20:46 ` Dmitry Safonov
2018-01-11 20:53 ` Eric Dumazet
2018-01-11 21:13 ` Dmitry Safonov
2018-01-12 5:41 ` Frederic Weisbecker
2018-01-12 5:23 ` Mike Galbraith
2018-01-12 10:13 ` Peter Zijlstra
2018-01-12 17:26 ` Linus Torvalds
2018-01-12 17:44 ` Mike Galbraith [this message]
2018-01-12 17:51 ` Linus Torvalds
2018-01-12 18:15 ` Mike Galbraith
2018-01-12 18:44 ` Mike Galbraith
2018-01-17 20:30 ` David Miller
2018-01-17 21:06 ` Linus Torvalds
2018-01-17 21:49 ` David Miller
2018-01-17 21:54 ` Thomas Gleixner
2018-01-17 21:58 ` Linus Torvalds
2018-01-17 22:00 ` Thomas Gleixner
2018-01-17 22:02 ` Eric Dumazet
2018-01-17 22:24 ` David Miller
2018-01-17 22:54 ` Thomas Gleixner
2018-02-06 16:56 ` Sebastian Andrzej Siewior
2018-02-13 16:36 ` Thomas Gleixner
2018-01-17 21:54 ` Linus Torvalds
2018-01-17 21:58 ` Thomas Gleixner
2018-01-12 19:28 ` Thomas Gleixner
2018-01-12 19:53 ` Frederic Weisbecker
2018-01-12 14:58 ` Frederic Weisbecker
2018-01-12 15:15 ` Mike Galbraith
2018-01-12 17:00 ` Frederic Weisbecker
2018-01-12 18:08 ` Mike Galbraith
2018-01-12 17:24 ` Linus Torvalds
2018-01-09 13:36 ` [RFC 2/2] softirq: Introduce mask for __do_softirq() Dmitry Safonov
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