From: John Ogness <john.ogness@linutronix.de>
To: Florian Paul Schmidt <mista.tapas@gmx.net>,
linux-rt-users@vger.kernel.org
Subject: Re: Raspberry Pi 5 and PREEMPT_RT (6.13.0-rc3)
Date: Fri, 20 Dec 2024 15:11:54 +0106 [thread overview]
Message-ID: <84bjx6h2kd.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <d445e582-4e49-4135-9d94-f52d72ec5df6@gmx.net>
Hi Florian,
On 2024-12-20, Florian Paul Schmidt <mista.tapas@gmx.net> wrote:
> I'm playing around with a Raspberry Pi 5 and a PREEMPT_RT kernel (raspberry
> pi 6.13.y branch) and wonder about the latencies I see. First I tried
> cyclictest and saw latencies in the upper 50s up to 80s or so under a
> kernel compile load.
...
> I still wonder though: How come the latencies are so large? Is the
> raspberry pi platform just not suited to reach lower latencies? Is
> everything working as expected? Are maybe the raspberry pi
> patches responsible for latency sources which are invisible in the
> traces? I there any hope for getting these latencies a little more
> under control?
There are various kernel configurations that affect latency. But I am
curious... Why do you think a maximum latency of 80us on an $80 board is
large? What maximum latencies are you expecting? And why do you think it
is not "under control"?
John Ogness
next prev parent reply other threads:[~2024-12-20 14:05 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-20 13:18 Raspberry Pi 5 and PREEMPT_RT (6.13.0-rc3) Florian Paul Schmidt
2024-12-20 14:05 ` John Ogness [this message]
2024-12-20 15:57 ` Florian Paul Schmidt
2024-12-22 10:32 ` Leon Woestenberg
2025-01-08 9:42 ` Florian Paul Schmidt
2025-01-12 15:14 ` Florian Paul Schmidt
2025-01-12 21:30 ` John Ogness
2025-01-13 9:15 ` Florian Paul Schmidt
2025-01-13 10:28 ` Florian Paul Schmidt
2025-01-13 11:09 ` John Ogness
2025-01-13 12:56 ` Florian Paul Schmidt
2025-01-14 10:28 ` Mike Galbraith
2025-02-14 8:31 ` Florian Paul Schmidt
2025-02-14 9:05 ` Mike Galbraith
2025-02-14 12:40 ` gene heskett
2025-02-14 12:06 ` Gabriele Monaco
2025-01-09 8:39 ` Florian Paul Schmidt
2025-01-07 14:39 ` Sebastian Andrzej Siewior
2025-01-08 9:48 ` Florian Paul Schmidt
2025-01-28 12:30 ` Tim Sander
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