From: David Hildenbrand <david@redhat.com>
To: Oscar Salvador <osalvador@suse.de>, Gregory Price <gourry@gourry.net>
Cc: linux-mm@kvack.org, linux-acpi@vger.kernel.org,
kernel-team@meta.com, x86@kernel.org,
linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com,
luto@kernel.org, peterz@infradead.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com, rafael@kernel.org,
lenb@kernel.org, gregkh@linuxfoundation.org,
akpm@linux-foundation.org, dan.j.williams@intel.com,
Jonathan.Cameron@huawei.com, alison.schofield@intel.com,
rrichter@amd.com, rppt@kernel.org, bfaccini@nvidia.com,
haibo1.xu@intel.com, dave.jiang@intel.com,
Ira Weiny <ira.weiny@intel.com>, Fan Ni <fan.ni@samsung.com>
Subject: Re: [PATCH v8 0/3] memory,x86,acpi: hotplug memory alignment advisement
Date: Tue, 1 Apr 2025 21:08:31 +0200 [thread overview]
Message-ID: <01d8cde7-0973-4303-bb5d-3d377a6862cb@redhat.com> (raw)
In-Reply-To: <Z-w2O8O9MGJ1Ok78@localhost.localdomain>
On 01.04.25 20:53, Oscar Salvador wrote:
> On Mon, Jan 27, 2025 at 10:34:02AM -0500, Gregory Price wrote:
>> v8: nits and tag pickups
>>
>> When physical address regions are not aligned to memory block size,
>> the misaligned portion is lost (stranded capacity).
>>
>> Block size (min/max/selected) is architecture defined. Most architectures
>> tend to use the minimum block size or some simplistic heurist. On x86,
>> memory block size increases up to 2GB, and is otherwise fitted to the
>> alignment of non-hotplug (i.e. not special purpose memory).
>
> I wonder if something like this could help us in improving the
> ridiculous situation of having 16MB memory-block size on powerpc.
They have this granularity because ... they want to add/remove memory in
16MiB on some powerpc dlpar machines :(
probe_memory_block_size() can query the hypervisor on the actual
hot(un)plug size. IIRC, QEMU sets it to 256 MiB.
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2025-04-01 19:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-27 15:34 [PATCH v8 0/3] memory,x86,acpi: hotplug memory alignment advisement Gregory Price
2025-01-27 15:34 ` [PATCH v8 1/3] memory: implement memory_block_advise/probe_max_size Gregory Price
2025-04-01 18:50 ` Oscar Salvador
2025-01-27 15:34 ` [PATCH v8 2/3] x86: probe memory block size advisement value during mm init Gregory Price
2025-04-01 18:51 ` Oscar Salvador
2025-01-27 15:34 ` [PATCH v8 3/3] acpi,srat: give memory block size advice based on CFMWS alignment Gregory Price
2025-04-01 18:52 ` Oscar Salvador
2025-04-01 18:33 ` [PATCH v8 0/3] memory,x86,acpi: hotplug memory alignment advisement Gregory Price
2025-04-01 18:53 ` Oscar Salvador
2025-04-01 19:08 ` David Hildenbrand [this message]
2025-04-02 9:39 ` Mike Rapoport
2025-04-02 10:07 ` David Hildenbrand
2025-04-01 19:44 ` Dan Williams
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