linux-kernel - [PATCH v2 0/2] x86/numa_emulation: Introduce uniform split capability

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Date:   Fri, 06 Jul 2018 09:07:55 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     mingo@...nel.org
Cc:     Wei Yang <richard.weiyang@...il.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        David Rientjes <rientjes@...gle.com>,
        Ingo Molnar <mingo@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [PATCH v2 0/2] x86/numa_emulation: Introduce uniform split
 capability

Changes since v1 [1]:
* Fix a pair of compile errors in 32-bit builds for 64-bit divides.

[1]: https://lkml.org/lkml/2018/5/26/190

---

The current numa emulation capabilities for splitting System RAM by a
fixed size or by a set number of nodes may result in some nodes being
larger than others. The implementation prioritizes establishing a
minimum usable memory size over satisfying the requested number of numa
nodes.

Introduce a uniform split capability that evenly partitions each
physical numa node into N emulated nodes. For example numa=fake=3U
creates 6 emulated nodes total on a system that has 2 physical nodes.

This capability is useful for debugging and evaluating platform
memory-side-cache capabilities as described by the ACPI HMAT (see
5.2.27.5 Memory Side Cache Information Structure in ACPI 6.2a)

See more details in patch2.

---

Dan Williams (2):
      x86/numa_emulation: Fix emulated-to-physical node mapping
      x86/numa_emulation: Introduce uniform split capability

 Documentation/x86/x86_64/boot-options.txt |    4 +
 arch/x86/mm/numa_emulation.c              |  107 ++++++++++++++++++++++++-----
 2 files changed, 91 insertions(+), 20 deletions(-)