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Tue, 1 Apr 2025 18:50:59 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id dX13L5M17GdBNwAAD6G6ig (envelope-from ); Tue, 01 Apr 2025 18:50:59 +0000 Date: Tue, 1 Apr 2025 20:50:50 +0200 From: Oscar Salvador To: Gregory Price 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, david@redhat.com, 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 , Fan Ni Subject: Re: [PATCH v8 1/3] memory: implement memory_block_advise/probe_max_size Message-ID: References: <20250127153405.3379117-1-gourry@gourry.net> <20250127153405.3379117-2-gourry@gourry.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250127153405.3379117-2-gourry@gourry.net> X-Spam-Level: X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_TWELVE(0.00)[28]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; R_RATELIMIT(0.00)[to_ip_from(RLj6zumtikrrmnnbmzkety5zmd)]; RCVD_COUNT_TWO(0.00)[2]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,intel.com:email] X-Spam-Score: -4.30 X-Spam-Flag: NO On Mon, Jan 27, 2025 at 10:34:03AM -0500, Gregory Price wrote: > Hotplug memory sources may have opinions on what the memblock size > should be - usually for alignment purposes. For example, CXL memory > extents can be 256MB with a matching alignment. If this size/alignment > is smaller than the block size, it can result in stranded capacity. > > Implement memory_block_advise_max_size for use prior to allocator init, > for software to advise the system on the max block size. > > Implement memory_block_probe_max_size for use by arch init code to > calculate the best block size. Use of advice is architecture defined. > > The probe value can never change after first probe. Calls to advise > after probe will return -EBUSY to aid debugging. > > On systems without hotplug, always return -ENODEV and 0 respectively. > > Suggested-by: Ira Weiny > Acked-by: David Hildenbrand > Acked-by: Mike Rapoport (Microsoft) > Acked-by: Dan Williams > Tested-by: Fan Ni > Reviewed-by: Ira Weiny > Signed-off-by: Gregory Price Acked-by: Oscar Salvador -- Oscar Salvador SUSE Labs