From: "Chen, Hongzhan" <hongzhan.chen@intel.com>
To: Richard Weinberger <richard.weinberger@gmail.com>,
Xenomai <xenomai@lists.linux.dev>
Subject: RE: i915 GPU woes
Date: Mon, 15 Apr 2024 04:28:07 +0000 [thread overview]
Message-ID: <PH7PR11MB74999755B34FF7230FCAE0F8F2092@PH7PR11MB7499.namprd11.prod.outlook.com> (raw)
In-Reply-To: <CAFLxGvyY+T1qQTq6gZ5UKfbZsxcan8adyj-Y95BCEA8SYe31=g@mail.gmail.com>
>-----Original Message-----
>From: Richard Weinberger <richard.weinberger@gmail.com>
>Sent: Monday, April 15, 2024 4:54 AM
>To: Xenomai <xenomai@lists.linux.dev>
>Subject: i915 GPU woes
>
>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?
Would you like to try to lock GPU frequency to minimum?
frequency=200
echo $frequency > /sys/class/drm/card0/gt_boost_freq_mhz
echo $frequency > /sys/class/drm/card0/gt_max_freq_mhz
echo $frequency > /sys/class/drm/card0/gt_min_freq_mhz
echo $frequency > /sys/class/drm/card0/gt_idle_freq_mhz
Regards
Hongzhan Chen
>
>--
>Thanks,
>//richard
next prev parent reply other threads:[~2024-04-15 4:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-14 20:54 i915 GPU woes Richard Weinberger
2024-04-15 4:28 ` Chen, Hongzhan [this message]
2024-04-15 4:38 ` Chen, Hongzhan
2024-04-15 21:46 ` Richard Weinberger
2024-04-16 2:02 ` Chen, Hongzhan
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