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Wysocki" , Len Brown , Dave Jiang , Dan Williams , Jonathan Cameron , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Ho-Ren (Jack) Chuang" , "Ho-Ren (Jack) Chuang" , "Ho-Ren (Jack) Chuang" , linux-cxl@vger.kernel.org, qemu-devel@nongnu.org Subject: Re: [PATCH v1] memory tier: consolidate the initialization of memory tiers Message-Id: <20240621183413.1638e7453a0bed2af5f44273@linux-foundation.org> In-Reply-To: <20240621044833.3953055-1-horen.chuang@linux.dev> References: <20240621044833.3953055-1-horen.chuang@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 6jsp4ee8ks1u83dnzridm6ei1zree5ux X-Rspamd-Queue-Id: 3F4931C0005 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1719020056-496928 X-HE-Meta: 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 xk3mv8U3 4i5W5F2Cl+z/uOJIZaHnT68X+S1xF3gvpL/CJcexa+ZP+txDERTjG6o0x4CIa/RzFttU48oUiSUjbj+f7iYbataNTCALXiseTJwyVaMsGwP9oODf9NoWszzjIe3CsgPtaysNKB0JHG33k+EmGZ4RIuKMnzQlPSamKpGhk9L8lAporNkKNNYGYvXpdkdQpbeu76fzwRYEy/f6WaDH3L5ue3v9o6HL17tR1BUNtJbF45Zn5zdJSQtd4JMHLNJBDp9BQfeDfsMwFvl457xlx5sn8uY1T/EUEjAG/Jyos1ynppLp9xTD77H4RbA236Mebc3fr700xo04IbpPwnJMyNn+9qszowa6sHK0Kg99z 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, 21 Jun 2024 04:48:30 +0000 "Ho-Ren (Jack) Chuang" wrote: > If we simply move the set_node_memory_tier() from memory_tier_init() to > late_initcall(), it will result in HMAT not registering the > mt_adistance_algorithm callback function, Immediate reaction: then don't do that! > because set_node_memory_tier() > is not performed during the memory tiering initialization phase, > leading to a lack of correct default_dram information. > > Therefore, we introduced a nodemask to pass the information of the > default DRAM nodes. The reason for not choosing to reuse > default_dram_type->nodes is that it is not clean enough. So in the end, > we use a __initdata variable, which is a variable that is released once > initialization is complete, including both CPU and memory nodes for HMAT > to iterate through. > > Besides, since default_dram_type may be checked/used during the > initialization process of HMAT and drivers, it is better to keep the > allocation of default_dram_type in memory_tier_init(). What is this patch actually aiming to do? Is it merely a code cleanup, or are there functional changes? > Signed-off-by: Ho-Ren (Jack) Chuang > --- > Hi all, > > The current memory tier initialization process is distributed across two > different functions, memory_tier_init() and memory_tier_late_init(). This > design is hard to maintain. Thus, this patch is proposed to reduce the > possible code paths by consolidating different initialization patches into one. Ah, there it is. Please make this the opening paragraph, not an aside buried below the ^---$. I'll await review input before proceeding with this, thanks.