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From: Thomas Gleixner <tglx@linutronix.de>
To: blinkin@email.it
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Len Brown <lenb@kernel.org>,
	linux-acpi@vger.kernel.org
Subject: Re: Bug report for kernel v4.15-rc8+
Date: Wed, 11 Aug 2021 16:20:41 +0200	[thread overview]
Message-ID: <87tujwhxl2.ffs@tglx> (raw)
In-Reply-To: <1437097118.2114098.1628689870926.JavaMail.zimbra@email.it>

On Wed, Aug 11 2021 at 15:51, blinkin@email.it wrote:
> 1) You're booting with an out of tree module
>
>   Uninstalled virtualbox, reproduced same behavior without the module.
>   dmesg outputs attached with and without the workaround
>   (dmesg_novboxdrv_clean.txt and dmesg_novboxdrv_irqaffinity0.txt)

Ok.

> 2) Please provide information what is consuming 90% of a CPU
>
>   top shows a kworker process consistently at 50% without the
>   workaround, 60% with the workaround. No significant activity amounts
>   from other processes.  Sometimes that 50% is split between two
>   kworker processes for a short time.  CPU core #0 activity is a
>   constant 60% without the workaround, 90% with the workaround

That's broken. /proc/interrupts gives some hint:

1) Stock kernel

>             CPU0       CPU1       CPU2       CPU3       
>    0:         10          0          0          0  IR-IO-APIC    2-edge      timer
>    1:          0          0          0          9  IR-IO-APIC    1-edge      i8042
>    8:          0          1          0          0  IR-IO-APIC    8-edge      rtc0
>    9:          0     923411          0          0  IR-IO-APIC    9-fasteoi   acpi

900k ACPI interrupts right after boot

>             CPU0       CPU1       CPU2       CPU3       
>    0:         10          0          0          0  IR-IO-APIC    2-edge      timer
>    1:          0          0          0         11  IR-IO-APIC    1-edge      i8042
>    8:          0          1          0          0  IR-IO-APIC    8-edge      rtc0
>    9:          0    4869059          0          0  IR-IO-APIC    9-fasteoi   acpi

One minute later it's 4.8M

With affinity forced to CPU0 it's even more:

>             CPU0       CPU1       CPU2       CPU3       
>    0:         10          0          0          0  IR-IO-APIC    2-edge      timer
>    1:          9          0          0          0  IR-IO-APIC    1-edge      i8042
>    8:          1          0          0          0  IR-IO-APIC    8-edge      rtc0
>    9:    7576456          0          0          0  IR-IO-APIC    9-fasteoi   acpi

7.5M right after boot

>             CPU0       CPU1       CPU2       CPU3       
>    0:         10          0          0          0  IR-IO-APIC    2-edge      timer
>    1:         11          0          0          0  IR-IO-APIC    1-edge      i8042
>    8:          1          0          0          0  IR-IO-APIC    8-edge      rtc0
>    9:   10992420          0          0          0  IR-IO-APIC    9-fasteoi   acpi

10.9M after one minute. Though the delta between right after boot and 1
minute later is in the same ballpark.

Cc'ed the ACPI people for clues.

Thanks,

        tglx

  reply	other threads:[~2021-08-11 14:20 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-06 15:45 Bug report for kernel v4.15-rc8+ blinkin
2021-08-10  6:46 ` Thomas Gleixner
2021-08-10 14:05   ` blinkin
2021-08-10 17:09     ` Thomas Gleixner
2021-08-11 13:51       ` blinkin
2021-08-11 14:20         ` Thomas Gleixner [this message]
2021-09-24 10:23           ` blinkin
  -- strict thread matches above, loose matches on Subject: below --
2021-12-17 13:31 blinkin
2022-06-10  9:52 blinkin
2022-06-10 13:17 ` Rafael J. Wysocki

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