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From: Thomas Gleixner <tglx@linutronix.de>
To: Bitao Hu <yaoma@linux.alibaba.com>, dianders@chromium.org,
 liusong@linux.alibaba.com, akpm@linux-foundation.org, pmladek@suse.com,
 kernelfans@gmail.com, deller@gmx.de, npiggin@gmail.com,
 tsbogend@alpha.franken.de, James.Bottomley@HansenPartnership.com,
 jan.kiszka@siemens.com
Cc: linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
 linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
 yaoma@linux.alibaba.com
Subject: Re: [PATCHv12 1/4] genirq: Provide a snapshot mechanism for
 interrupt statistics
In-Reply-To: <20240306125208.71803-2-yaoma@linux.alibaba.com>
References: <20240306125208.71803-1-yaoma@linux.alibaba.com>
 <20240306125208.71803-2-yaoma@linux.alibaba.com>
Date: Tue, 09 Apr 2024 11:58:34 +0200
Message-ID: <87frvu7t85.ffs@tglx>
Precedence: bulk
MIME-Version: 1.0
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On Wed, Mar 06 2024 at 20:52, Bitao Hu wrote:
> The soft lockup detector lacks a mechanism to identify interrupt storms
> as root cause of a lockup. To enable this the detector needs a
> mechanism to snapshot the interrupt count statistics on a CPU when the
> detector observes a potential lockup scenario and compare that against
> the interrupt count when it warns about the lockup later on. The number
> of interrupts in that period give a hint whether the lockup might be
> caused by an interrupt storm.
>
> Instead of having extra storage in the lockup detector and accessing
> the internals of the interrupt descriptor directly, convert the per CPU
> irq_desc::kstat_irq member to a data structure which contains the
> counter plus a snapshot member and provide interfaces to take a
> snapshot of all interrupts on the current CPU and to retrieve the delta
> of a specific interrupt later on.
>
> Originally-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com>
> Reviewed-by: Liu Song <liusong@linux.alibaba.com>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>

This does not apply anymore.

Also can you please split this apart to convert kstat_irqs to a struct
with just the count in it and then add the snapshot mechanics on top.

Thanks,

        tglx