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Date: Fri, 27 Feb 2026 13:27:17 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-kernel@vger.kernel.org, "Paul E. McKenney" <paulmck@kernel.org>,
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 <aboorvad@linux.ibm.com>
Subject: Re: [PATCH v18 0/3] Improve proc RSS accuracy
Message-Id: <20260227132717.c811f04b63a332f88e354e08@linux-foundation.org>
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On Fri, 27 Feb 2026 10:37:27 -0500 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> This series introduces the hierarchical tree counter (hpcc) to increase
> accuracy of approximated RSS counters exposed through proc interfaces.
> 
> With a test program hopping across CPUs doing frequent mmap/munmap
> operations, the upstream implementation approximation reaches a 1GB
> delta from the precise value after a few minutes, compared to a 80MB
> delta with the hierarchical counter. The hierarchical counter provides a
> guaranteed maximum approximation inaccuracy of 192MB on that hardware
> topology.
> 
> This series is based on tag v7.0-rc1.
> 
> The main changes since v17:
> - Fix patch series bissectability.
> - Export GPL symbols for kunit tests.
> - Improve kunit tests coverage.
> - Fix kunit tests wait queue head reinit bug.
> - Fix an out-of-bound on bootup on configurations where nr_cpu_ids is
>   close to NR_CPUS.

Updated, thanks.

> Andrew, this series targets 7.1.

Some review would be useful.  Can you think of someone we could ask to
undertake this?