From: Richard Weinberger <richard.weinberger@gmail.com>
To: Xenomai <xenomai@lists.linux.dev>
Subject: i915 GPU woes
Date: Sun, 14 Apr 2024 22:54:08 +0200 [thread overview]
Message-ID: <CAFLxGvyY+T1qQTq6gZ5UKfbZsxcan8adyj-Y95BCEA8SYe31=g@mail.gmail.com> (raw)
Hi!
On an Intel(R) Celeron(R) J6413 4-core system, I've observed the
following symptoms:
As soon as an X11 application redraws frequently, real-time
performance suffers. In such situations, the i915 IRQ takes between
200 and 1500 microseconds, seemingly blocking the real-time thread for
an equivalent amount of time. Since the i915 IRQ is a) on the Linux
side and b) pinned to a different core than the real-time thread, it
does not seem to be a software issue.
With extensive tracing, I've noticed that both the i915 IRQ and my
real-time thread stall when accessing memory-mapped IO (the real-time
application drivers an Ethernet card in userspace).
It appears that the GPU is doing something that dramatically slows
down MMIO access across all CPU cores. With graphics disabled, the
application runs smoothly.
The following i915 module parameters are already set:
i915.disable_power_well=0 i915.enable_dc=0 i915.enable_guc=2
i915.enable_rc6=0
I'm currently using Xenomai 3.2.4 on Linux kernel version 6.1, though
I don't think this detail is very significant.
Does anyone have suggestions on what else to try?
--
Thanks,
//richard
next reply other threads:[~2024-04-14 20:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-14 20:54 Richard Weinberger [this message]
2024-04-15 4:28 ` i915 GPU woes Chen, Hongzhan
2024-04-15 4:38 ` Chen, Hongzhan
2024-04-15 21:46 ` Richard Weinberger
2024-04-16 2:02 ` Chen, Hongzhan
2024-05-07 9:39 ` Richard Weinberger
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