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From: horen.chuang@linux.dev Message-ID: TLS-Required: No Subject: Re: [PATCH v1] memory tier: consolidate the initialization of memory tiers To: "Andrew Morton" Cc: "Jonathan Cameron" , "Huang, Ying" , "Gregory Price" , aneesh.kumar@linux.ibm.com, mhocko@suse.com, tj@kernel.org, john@jagalactic.com, "Eishan Mirakhur" , "Vinicius Tavares Petrucci" , "Ravis OpenSrc" , "Alistair Popple" , "Srinivasulu Thanneeru" , "SeongJae Park" , "Rafael J. Wysocki" , "Len Brown" , "Dave Jiang" , "Dan Williams" , 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 In-Reply-To: <20240621183413.1638e7453a0bed2af5f44273@linux-foundation.org> References: <20240621044833.3953055-1-horen.chuang@linux.dev> <20240621183413.1638e7453a0bed2af5f44273@linux-foundation.org> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 56CD610000A X-Stat-Signature: dx7zpiyyi4um5mbopbc5gghzebts6q1h X-HE-Tag: 1719296657-749638 X-HE-Meta: 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 njhJKTBJ EtRDYy21ATRdWP5dKFfEaIMHG8TikeiOA42GnDSnb/kWFxQTudo6b/fC2C3hqevL+T9ENbAp7y7XEnfCTStvhX1yTFO4PIpbyjyaxcnKZuiDE9wypBYbGAbFJkX3p/U5Gf+s4Jq+DCCj38XtU6EN7k2OWmUkWUR/YSxeqSZ+A49Lvjr1/KhGLBIKgrUNzOzAuFII/CFT7ub62HyTjoHvdjYtN0I5rxVrfFfSaVP/0OZGmU2WINotXbeYgRBbWqDfBIbmH1QnSN8m8uPCyww8NCrksO2Q+IPDEPGgEQPmX81kZ9QY6r63DaSsW2A== 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: June 21, 2024 at 6:34 PM, "Andrew Morton" wro= te: Hi Andrew, Thanks for the feedback. I will send a v2 with the patch description written in a cover letter. >=20 >=20On Fri, 21 Jun 2024 04:48:30 +0000 "Ho-Ren (Jack) Chuang" wrote: >=20 >=20>=20 >=20> If we simply move the set_node_memory_tier() from memory_tier_init(= ) to > >=20 >=20> late_initcall(), it will result in HMAT not registering the > >=20 >=20> mt_adistance_algorithm callback function, > >=20 >=20 > Immediate reaction: then don't do that! >=20 >=20>=20 >=20> because set_node_memory_tier() > >=20 >=20> is not performed during the memory tiering initialization phase, > >=20 >=20> leading to a lack of correct default_dram information. > >=20 >=20>=20=20 >=20>=20 >=20> Therefore, we introduced a nodemask to pass the information of the > >=20 >=20> default DRAM nodes. The reason for not choosing to reuse > >=20 >=20> default_dram_type->nodes is that it is not clean enough. So in the= end, > >=20 >=20> we use a __initdata variable, which is a variable that is released= once > >=20 >=20> initialization is complete, including both CPU and memory nodes fo= r HMAT > >=20 >=20> to iterate through. > >=20 >=20>=20=20 >=20>=20 >=20> Besides, since default_dram_type may be checked/used during the > >=20 >=20> initialization process of HMAT and drivers, it is better to keep t= he > >=20 >=20> allocation of default_dram_type in memory_tier_init(). > >=20 >=20 > What is this patch actually aiming to do? Is it merely a code cleanup, >=20 >=20or are there functional changes? >=20 >=20>=20 >=20> Signed-off-by: Ho-Ren (Jack) Chuang > >=20 >=20> --- > >=20 >=20> Hi all, > >=20 >=20>=20=20 >=20>=20 >=20> The current memory tier initialization process is distributed acro= ss two > >=20 >=20> different functions, memory_tier_init() and memory_tier_late_init(= ). This > >=20 >=20> design is hard to maintain. Thus, this patch is proposed to reduce= the > >=20 >=20> possible code paths by consolidating different initialization patc= hes into one. > >=20 >=20 > Ah, there it is. Please make this the opening paragraph, not an aside >=20 >=20buried below the ^---$. >=20 >=20I'll await review input before proceeding with this, thanks. >