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[173.79.56.208]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6e1afcd59d6sm53752286d6.87.2025.01.21.11.56.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Jan 2025 11:56:37 -0800 (PST) Date: Tue, 21 Jan 2025 14:56:35 -0500 From: Gregory Price To: "Huang, Ying" Cc: Joshua Hahn , hyeonggon.yoo@sk.com, rafael@kernel.org, lenb@kernel.org, gregkh@linuxfoundation.org, akpm@linux-foundation.org, honggyu.kim@sk.com, rakie.kim@sk.com, dan.j.williams@intel.com, Jonathan.Cameron@huawei.com, dave.jiang@intel.com, horen.chuang@linux.dev, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-mm@kvack.org, kernel-team@meta.com Subject: Re: [PATCH v3] Weighted interleave auto-tuning Message-ID: References: <20250115185854.1991771-1-joshua.hahnjy@gmail.com> <87ikq8h0w4.fsf@DESKTOP-5N7EMDA> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ikq8h0w4.fsf@DESKTOP-5N7EMDA> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: DE0001C0015 X-Stat-Signature: 8gu39tpiki9rh6z3dquakh4csa7qm6nu X-Rspam-User: X-HE-Tag: 1737489398-853203 X-HE-Meta: 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 32bSqti6 gTLBA3fDua/wpchH/I8XIwhLQq1MY80BOS2ygRVimU3uQOfIdLtW9OFVGmad+IlojHckonZ/jAVQ4NOfYf1zzBNshGjFJxKXBUcECngDVK6ZDwsMcaTjyoiGO3vaGZb9MF4WIbDAN22Je6mELp+dBfz7nxVbhYfYM+R8kCMK49A7Q4u8WpWXyvfdDLdLekWeppquKisADB7ZaJkX597DHXXKapaq0RuedXF0xWyuFwahj3Xh3mPlDzbcELW4u0Lz0WoSYLhV+yKAwbvPOvrqgYIQ3olQW1QHb0X8WtPejE6R63mVIX1d7NkrzYbp63FA4W9cip15UFqU0KWTo7IYzuqGYcCadTxXylBMKOqxXSZFrF5PyI75oZkkSBbtN+3Z5/EsOJcMkwmXNYxxAlPqccwRC4w== 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 Tue, Jan 21, 2025 at 07:17:15PM +0800, Huang, Ying wrote: ... snip ... > > Unless it's possible we will add more modes in the future, this is kind > of overkill for me. How about something simpler as below? > > $ cat auto > true > $ echo 0 > auto > $ cat auto > false We have discussed having a dynamic-mode where the weights might adjust on the fly based on system-state, but i think this ends up being controlled under mempolicy/dynamic_interleave or something. So this seems reasonable. > > static u8 __rcu *iw_table; > > static DEFINE_MUTEX(iw_table_lock); > > +static const int weightiness = 32; > > +static bool weighted_interleave_auto = true; > > I still prefer to use 2 iw_table, one is for default, the other is for > manual. The default one will be used if the manual one is NULL. Both > are protected by RCU. The default one can be updated upon hotplug > blindly. This makes the whole model easier to be understood IMHO. > > What do you think about that. > only question is, lets say you have `cat auto node0 node1` -> `true 5 1` and you do echo 0 > auto what should a subsequent `cat auto node0 node1` output? `false 5 1` or `false 1 1` Then lets say we do echo 7 > node0 what should echo true > auto result in? `true 5 1` or `true 7 1` The current code makes sure that when you switch modes from auto to manual, it inherits the current state - instead of there being some hidden state that suddenly takes precedence. So I prefer to just have one IW array and no hidden state. ~Gregory