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b=peaNE9x+uUJuwo6gX2ZdWtag2VzEWukSKKq6/Q6bJa4yKYnZXKotkurQAfcW8FEmT m65zJDr/cHp4Bfc3L5cbJgBEj8x3vIISQyvRQ8VEPw7U8WqKOykKzvg3bT/0rfc+iy oFcEKy2T12/LpWThDDEYlcMIdt4uDmFLFy/quQntzXAB8aD2yA7nW/i4GSrDhe3yAV OBm5HE58IbELIOvshb7bOguI8YMLLl6Juyq2tb+9HweY3rH1gRHrsEaDQLgwgPDzLD 5CZrKERAhofgk+shQAZW1BxLwoJvwWesV/0wnTK3DqPO3fwFG6du+q39UMOv3DVP1n +DkHfA4PAFBuQ== Date: Fri, 1 Nov 2024 18:02:32 +0200 From: Mike Rapoport To: Gregory Price Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org, Jonathan.Cameron@huawei.com, dan.j.williams@intel.com, rrichter@amd.com, Terry.Bowman@amd.com, dave.jiang@intel.com, ira.weiny@intel.com, alison.schofield@intel.com, 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, osalvador@suse.de, gregkh@linuxfoundation.org, akpm@linux-foundation.org Subject: Re: [PATCH v5 2/3] x86: probe memory block size advisement value during mm init Message-ID: References: <20241101134706.1185-1-gourry@gourry.net> <20241101134706.1185-3-gourry@gourry.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241101134706.1185-3-gourry@gourry.net> X-Rspam-User: X-Rspamd-Queue-Id: 50869180024 X-Rspamd-Server: rspam11 X-Stat-Signature: owqbtafruax9xz7j5wnyepcnrqcrpayu X-HE-Tag: 1730477178-255836 X-HE-Meta: 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 YjiTj/61 91wKdIm/R+Bg/eum+AdORxZ3Bvp03K/AdJXRclfgCAnCTIPIZQKfPBNx9RSiCM8+UBoRZoZwc3rmduLjQtRqwyOkX82WkSRLtUtCmdyvQ4OUF6rGup7XP+trwO7jkbFHiyKOrh98z8ZYJ191G1Jeium4CZXAl7c1KGkIZid/7e2PjmnQ/ZIAVC/vF2iv8BjU2tPrNQA2B1iTUsmMUDZKrseofv0GOl90uR6L34ryucKCGkQ46xMixLFFCygM76SdJPWKhVcAB2ufimd2MInSjZTsM0lX/lEcNdzIgf+qcJsfZZ/SS/KaPq+PfSSPd8gWT65Dbm50rKtwRF36iGOxmKJ/XvejgqE2cNGpDc7OvHeHmchY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Nov 01, 2024 at 09:47:04AM -0400, Gregory Price wrote: > Systems with hotplug may provide an advisement value on what the > memblock size should be. Probe this value when the rest of the > configuration values are considered. > > The new heuristic is as follows > > 1) set_memory_block_size_order value if already set (cmdline param) > 2) minimum block size if memory is less than large block limit > 3) if no hotplug advice: Max block size if system is bare-metal, > otherwise use end of memory alignment. > 4) if hotplug advice: lesser of advice and end of memory alignment. > > Suggested-by: David Hildenbrand > Signed-off-by: Gregory Price > Acked-by: David Hildenbrand Acked-by: Mike Rapoport (Microsoft) > --- > arch/x86/mm/init_64.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index ff253648706f..f1a495e998ce 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1452,16 +1452,21 @@ static unsigned long probe_memory_block_size(void) > } > > /* > - * Use max block size to minimize overhead on bare metal, where > - * alignment for memory hotplug isn't a concern. > + * When hotplug alignment is not a concern, maximize blocksize > + * to minimize overhead. Otherwise, align to the lesser of advice > + * alignment and end of memory alignment. > */ > - if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) { > + bz = memory_block_advised_max_size(); > + if (!bz) { > bz = MAX_BLOCK_SIZE; > - goto done; > + if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) > + goto done; > + } else { > + bz = max(min(bz, MAX_BLOCK_SIZE), MIN_MEMORY_BLOCK_SIZE); > } > > /* Find the largest allowed block size that aligns to memory end */ > - for (bz = MAX_BLOCK_SIZE; bz > MIN_MEMORY_BLOCK_SIZE; bz >>= 1) { > + for (; bz > MIN_MEMORY_BLOCK_SIZE; bz >>= 1) { > if (IS_ALIGNED(boot_mem_end, bz)) > break; > } > -- > 2.43.0 > -- Sincerely yours, Mike.