From: "Huang, Ying" <ying.huang@intel.com>
To: "Ho-Ren (Jack) Chuang" <horenchuang@bytedance.com>
Cc: "Hao Xiang" <hao.xiang@bytedance.com>,
"Gregory Price" <gourry.memverge@gmail.com>,
aneesh.kumar@linux.ibm.com, mhocko@suse.com, tj@kernel.org,
john@jagalactic.com, "Eishan Mirakhur" <emirakhur@micron.com>,
"Vinicius Tavares Petrucci" <vtavarespetr@micron.com>,
"Ravis OpenSrc" <Ravis.OpenSrc@micron.com>,
"Alistair Popple" <apopple@nvidia.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Len Brown <lenb@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Dave Jiang <dave.jiang@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, "Ho-Ren (Jack) Chuang" <horenc@vt.edu>,
"Ho-Ren (Jack) Chuang" <horenchuang@gmail.com>,
linux-cxl@vger.kernel.org, qemu-devel@nongnu.org
Subject: Re: [PATCH v1 0/1] Improved Memory Tier Creation for CPUless NUMA Nodes
Date: Mon, 04 Mar 2024 10:45:02 +0800 [thread overview]
Message-ID: <87frx6btqp.fsf@yhuang6-desk2.ccr.corp.intel.com> (raw)
In-Reply-To: <20240301082248.3456086-1-horenchuang@bytedance.com> (Ho-Ren Chuang's message of "Fri, 1 Mar 2024 08:22:44 +0000")
"Ho-Ren (Jack) Chuang" <horenchuang@bytedance.com> writes:
> The memory tiering component in the kernel is functionally useless for
> CPUless memory/non-DRAM devices like CXL1.1 type3 memory because the nodes
> are lumped together in the DRAM tier.
> https://lore.kernel.org/linux-mm/PH0PR08MB7955E9F08CCB64F23963B5C3A860A@PH0PR08MB7955.namprd08.prod.outlook.com/T/
I think that it's unfair to call it "useless". Yes, it doesn't work if
the CXL memory device are not enumerate via drivers/dax/kmem.c. So,
please be specific about in which cases it doesn't work instead of too
general "useless".
> This patchset automatically resolves the issues. It delays the initialization
> of memory tiers for CPUless NUMA nodes until they obtain HMAT information
> at boot time, eliminating the need for user intervention.
> If no HMAT specified, it falls back to using `default_dram_type`.
>
> Example usecase:
> We have CXL memory on the host, and we create VMs with a new system memory
> device backed by host CXL memory. We inject CXL memory performance attributes
> through QEMU, and the guest now sees memory nodes with performance attributes
> in HMAT. With this change, we enable the guest kernel to construct
> the correct memory tiering for the memory nodes.
>
> Ho-Ren (Jack) Chuang (1):
> memory tier: acpi/hmat: create CPUless memory tiers after obtaining
> HMAT info
>
> drivers/acpi/numa/hmat.c | 3 ++
> include/linux/memory-tiers.h | 6 +++
> mm/memory-tiers.c | 76 ++++++++++++++++++++++++++++++++----
> 3 files changed, 77 insertions(+), 8 deletions(-)
--
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2024-03-04 2:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-01 8:22 [PATCH v1 0/1] Improved Memory Tier Creation for CPUless NUMA Nodes Ho-Ren (Jack) Chuang
2024-03-01 8:22 ` [PATCH v1 1/1] memory tier: acpi/hmat: create CPUless memory tiers after obtaining HMAT info Ho-Ren (Jack) Chuang
2024-03-04 2:40 ` Huang, Ying
2024-03-05 9:28 ` [External] " Ho-Ren (Jack) Chuang
2024-03-06 2:25 ` Huang, Ying
2024-03-06 3:55 ` Ho-Ren (Jack) Chuang
2024-03-04 2:45 ` Huang, Ying [this message]
2024-03-05 6:22 ` [External] Re: [PATCH v1 0/1] Improved Memory Tier Creation for CPUless NUMA Nodes Ho-Ren (Jack) Chuang
2024-03-05 6:34 ` Huang, Ying
2024-03-05 7:10 ` Ho-Ren (Jack) Chuang
2024-03-05 7:37 ` Huang, Ying
2024-03-04 3:07 ` fan
2024-03-04 8:40 ` [EXT] " Srinivasulu Opensrc
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