From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id A51D2D339A4 for ; Mon, 28 Oct 2024 17:31:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3054A6B0098; Mon, 28 Oct 2024 13:31:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B65E6B0099; Mon, 28 Oct 2024 13:31:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 12F6F6B009A; Mon, 28 Oct 2024 13:31:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id E70B26B0098 for ; Mon, 28 Oct 2024 13:31:22 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 90054120F8F for ; Mon, 28 Oct 2024 17:31:22 +0000 (UTC) X-FDA: 82723701228.13.62DBC22 Received: from nyc.source.kernel.org (nyc.source.kernel.org [147.75.193.91]) by imf26.hostedemail.com (Postfix) with ESMTP id 23352140003 for ; Mon, 28 Oct 2024 17:31:02 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=DilTPWI2; spf=pass (imf26.hostedemail.com: domain of rppt@kernel.org designates 147.75.193.91 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1730136470; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Wo+3GK7op3UZVW690fNBpnfO2nqFBu/tAlTHDc5RXN8=; b=2UZIX34gvvq65Ve2ntj9vJNk65kR/vDQYr2Ff9Vsa0MTkCOUIG8RdGRGfWk5MuG5q3eDCQ 0/WsEpQYxQpiuO+6PshonHNlFXPq/uaUSH+bnwrB1jNkxIhJu6ruZQUhfZh99phD7qEYt1 Qc8K8n4h9uAAwURJ2nmg/TJBEwJFI1E= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=DilTPWI2; spf=pass (imf26.hostedemail.com: domain of rppt@kernel.org designates 147.75.193.91 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1730136470; a=rsa-sha256; cv=none; b=nEQ6CZ2sR8bIJtc1Sj7XfT7AlXbLDmbipR8ffiLEs5THgvfWjYdsEL9LWCVkQOlUMNab+/ bdSE3Sxp5CorugoFWUAqKSfTRBnKQVbxgk7SOUj79rjNnwlNQhxIXY4jLdS/K04TjUOJql SM5CR4RwOYYIv62Ievp1o6pM46aT0Lk= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id A6A6DA42A17; Mon, 28 Oct 2024 17:29:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4873EC4CEC3; Mon, 28 Oct 2024 17:31:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730136679; bh=RW3lMh/hj64PO7Sxfncf66yFZBftog/9Sb9K431heYE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DilTPWI2rFgKWdJkDIDILeTnqKWiYmCXqWlmb54U6CJf8qTHZG7M+r6aRuSON/xE/ j2SBn7YoNdGJlf6/tm5g4S+P46+f3B7MDcjGb2dYnqkOwgsX7cmojrKu+dhc7jZObe /ssvsoriqq/SeLAZCqUIMMrZjbPGDlPJhf3Ll6eSJQRHzh2A/gkb8t6WIqiw/HYh3K r8mymXC0YzRE8HzAAeU9r6SJrJtiYmdcuKTlzPCabdY5yoye0XK3SGLZUzZOV8M/gR 3MtR2Vlgj9jVkkfzVJE/zAx3eosYhNyyuM+A8js5cNEtUdYEQqKXGaqAp5zve5MES0 QvS50wM/odG7A== Date: Mon, 28 Oct 2024 19:27:21 +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@kvack.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 v3 1/3] memory: implement memory_block_advise/probe_max_size Message-ID: References: <20241022213450.15041-1-gourry@gourry.net> <20241022213450.15041-2-gourry@gourry.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241022213450.15041-2-gourry@gourry.net> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 23352140003 X-Stat-Signature: g6qti615ws977tshy8fyx68u7s5nowk5 X-Rspam-User: X-HE-Tag: 1730136662-5542 X-HE-Meta: U2FsdGVkX190piaMXVWwRKTmtQAWQ4cFlO+NIMuIJ+7p2gHEAKCUssyle01JTEXn2UoNNr43KnxP6xLVB1Wxeo54bjVxjiQzKvqVJJ6QhhhDxBIJ8U7cRdzUUE4A2Dm0Etm7QrXeIEU8nWVrVRZJ4TdVbqcyZ9GaRKWMXy/0UGZwY1KQKinUKfTZDSYAesf/6UO2Qim2UzV9aMaYQgsiyXwx4bt/BDkUpki9zx4ev/MS7Vc5UorKyUPmVjZmhbBG8k+GOLFplD4CoVTzRTgmqI5FOKO7aQR8qGLE4GpsNVPA7XLwPR9fx49JobDbGng4L0Wp5BLTogBZZldQnqT9ALz9NHKA+7vpIyKQ3h+OJwCTB5k/N+J6rAYp7WIyl9yNyMFUg9+2aXDXYwIdAOLMOg/kNTcAPRhpWypMdyC9cnlf/mxnOljQ4gZQVaVSMCHIWP8y3QXDIw9BwTECwK9j7TWz6CnQzSrs5hmuWrpegl+M6TEbQLcA+WkXqWzatV6RlS9083Zy+IxY3KfyYAVzMa7FnR7g5U+tAtJgOe8rbNHlU7Bjo7pKChCPeVc6n/xtO32KhktnfnKr8M/YrDju8aVGsF1qdCH+6YFOKs5We/AX/bopgkU+dcI+9icxF5sFli0Ht82oOkExYxiSmhNMUpvUvDKMXayFdwxroIJKNRRq4cX9hhf3po+g7VygzykkHfGEdouhLdyD3qN672xIKau8rYYjF4yxBuBDPYFfIDJFAJsZ+1BIUlGI5oR/flKwzx0aEcxrX3wGLlNs+hA0Qh5rv6pmCY9tmRjmOZ08Mat3YtQtzKS3mWSy42SGzw9W7Bi4GhG6qFdPNNoRfC+UAg+1sYMBpcZlDbNLLWSuNCzmaDxOVru34ob3JSKGcRAsiDBYlI0642xVlYZkmytrhbTm6GUpTXhj9dmbDzHVSES8cOhCBA2OYVBlgqfTMbLCk8dvQnJMa78zgG5YdFI DGQwaM0U wxFGqYHSHCstry3HvB/C2vjDYORwr0vK0lVgtcNN38SYbCWfC59IX0kIfDUti+Ly1s+BrcCNdbkLC9dNjRddNyWwQJF4QGg9PEeTjcibVLTB5xmbyEMGK7rqrhWR/2y35FhyIsgaGBAqaZRkHkEwBbQc1Hq3avypxazyuK2W7hV5ERDUPy5rFRetTU0iU5gGz3T6LHDhVAbk6Bb8H5BtcVMcNnQTPVTSQVl/VXm1FDZDM0HJ4J5M+zjZ54ni2bKlzRfJNSRutttNwabbYSnKvzQB84Wv+C7givxc/Ecz4RCSPNigpGmLbIZIdjDaKjSAUwWUvjeSH8JVYpsSWg78tREfu6uhzduhCmWuOnNQhx9wm2gosrKANyIgAcj2jFzNX2hkw 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: Hi, On Tue, Oct 22, 2024 at 05:34:48PM -0400, 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 > Signed-off-by: Gregory Price > --- > drivers/base/memory.c | 43 ++++++++++++++++++++++++++++++++++++++++++ > include/linux/memory.h | 10 ++++++++++ > 2 files changed, 53 insertions(+) > > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index 67858eeb92ed..a0fd9e1451aa 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -110,6 +110,49 @@ static void memory_block_release(struct device *dev) > kfree(mem); > } > > +/* If the intention for this to be a kernel-doc comment it should start with /**, should be placed right before the documented function and start with a brief function description > + * @size: suggestion for maximum block size. must be aligned on power of 2. > + * > + * Early boot software (pre-allocator init) may advise archs on the max block > + * size.This value can only decrease after initialization, as the intent is to > + * identify the largest supported alignment for all sources. > + * > + * Use of this value is arch dependent, as is min/max block size. > + * > + * Returns: 0 on success > + * -EINVAL if size is 0 or not pow2 aligned > + * -EBUSY if value has already been probed > + */ > +static size_t memory_block_advised_sz; > +static bool memory_block_size_probed; > +int memory_block_advise_max_size(size_t bz) size seems to me a better parameter name :) > +{ > + if (!bz || (bz & (bz - 1)) != 0) we have is_power_of_2() > + return -EINVAL; > + > + if (memory_block_size_probed) > + return -EBUSY; > + > + if (memory_block_advised_sz) > + memory_block_advised_sz = min(bz, memory_block_advised_sz); > + else > + memory_block_advised_sz = bz; > + > + return 0; > +} > + > +/* should it be kernel-doc? > + * memory_block_probe_max_size provides a suggested maximum memory block > + * size value. After the first call, the value can never change. > + * > + * Returns: advised size in bytes, or 0 if never set. > + */ > +size_t memory_block_probe_max_size(void) > +{ > + memory_block_size_probed = true; > + return memory_block_advised_sz; > +} > + > unsigned long __weak memory_block_size_bytes(void) > { > return MIN_MEMORY_BLOCK_SIZE; > diff --git a/include/linux/memory.h b/include/linux/memory.h > index c0afee5d126e..47c00d6e1165 100644 > --- a/include/linux/memory.h > +++ b/include/linux/memory.h > @@ -149,6 +149,14 @@ static inline int hotplug_memory_notifier(notifier_fn_t fn, int pri) > { > return 0; > } > +static inline int memory_block_advise_max_size(size_t size) > +{ > + return -ENODEV; > +} > +static inline size_t memory_block_probe_max_size(void) > +{ > + return 0; > +} > #else /* CONFIG_MEMORY_HOTPLUG */ > extern int register_memory_notifier(struct notifier_block *nb); > extern void unregister_memory_notifier(struct notifier_block *nb); > @@ -181,6 +189,8 @@ int walk_dynamic_memory_groups(int nid, walk_memory_groups_func_t func, > void memory_block_add_nid(struct memory_block *mem, int nid, > enum meminit_context context); > #endif /* CONFIG_NUMA */ > +int memory_block_advise_max_size(size_t size); > +size_t memory_block_probe_max_size(void); > #endif /* CONFIG_MEMORY_HOTPLUG */ > > /* > -- > 2.43.0 > -- Sincerely yours, Mike.