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From: Thomas Gleixner <tglx@linutronix.de>
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To: Luigi Rizzo <lrizzo@google.com>
Cc: Marc Zyngier <maz@kernel.org>, Luigi Rizzo <rizzo.unipi@gmail.com>,
 Paolo Abeni <pabeni@redhat.com>, Andrew Morton
 <akpm@linux-foundation.org>, Sean Christopherson <seanjc@google.com>,
 Jacob Pan <jacob.jun.pan@linux.intel.com>, linux-kernel@vger.kernel.org,
 linux-arch@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>, Willem de
 Bruijn <willemb@google.com>
Subject: Re: [PATCH v2 4/8] genirq: soft_moderation: implement adaptive
 moderation
In-Reply-To: <CAMOZA0KKJ9S45-LnLtYKn-L8dL71tsfs29c6ZL3bkuTcNXorAw@mail.gmail.com>
References: <20251116182839.939139-1-lrizzo@google.com>
 <20251116182839.939139-5-lrizzo@google.com> <87jyzo757y.ffs@tglx>
 <CAMOZA0KKJ9S45-LnLtYKn-L8dL71tsfs29c6ZL3bkuTcNXorAw@mail.gmail.com>
Date: Tue, 18 Nov 2025 10:00:57 +0100
Message-ID: <875xb77m0m.ffs@tglx>
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On Mon, Nov 17 2025 at 22:34, Luigi Rizzo wrote:
> (First world problem, for sure: I have examples for AMD, Intel, Arm,
> all of them with 100+ CPUs per numa node, and 160-480 CPUs total)
> On some of the above platforms, MSIx interrupts cause heavy serialization
> of all other PCIe requests. As a result, when the total interrupt rate exceeds
> 1-2M intrs/s, I/O throughput degrades by up to 4x and more.

Is it actually the sum of all interrupts in the system or is it
segmented per root port?

Thanks,

        tglx