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[173.79.56.208]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7be614ef273sm678089685a.98.2025.01.22.08.53.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jan 2025 08:53:50 -0800 (PST) Date: Wed, 22 Jan 2025 11:53:48 -0500 From: Gregory Price To: Joshua Hahn Cc: "Huang, Ying" , 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: <8734hbiq7j.fsf@DESKTOP-5N7EMDA> <20250122155935.1282897-1-joshua.hahnjy@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250122155935.1282897-1-joshua.hahnjy@gmail.com> X-Rspamd-Queue-Id: CA24516000A X-Stat-Signature: sn8tzq95ee4ant5zrb6ifcwubmup4xsb X-Rspamd-Server: rspam08 X-Rspam-User: X-HE-Tag: 1737564831-337866 X-HE-Meta: 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 6/feBnP/ KOmT9fia4qcduJv5FL1NVh07hMtSjWp+apdxiA6Da2rKBg6zyyCiE2d9sUkaRwvIbM880tdnhnKBdqrPvPYo9WpseHGQyKLuPe52X9NyGNU60lyKM3+IsQDpkCA8spr8c3qU9LtMppCBqCBrK0ldWDwXZJ3p4Hjv4b/AfR0Ks6vpPiq9ACdiKsHPytGoNOTbDqxlBi1b+uyq+Gmkishozjds/s7CNdq9Fpvp30pLWM4mJcfJ6AOXQF1Si3r8xU+gof2EeBPB+sG1IfsyFhOMtyG2DvuKJQVxJV819tqPnegolcEr9O0N64WH6anwCgxi2+IhrT9Bclqmkr8vRTmlsuhNPE14uoA0vT3CcFlSkdrKAZH6oHOpv7UEPo/YmKQhTr3AFmzmhTp2wsOGQyEhrGyumtVK7su0yBOPi+r4NtORwIuQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000057, 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 Wed, Jan 22, 2025 at 07:59:34AM -0800, Joshua Hahn wrote: > On Wed, 22 Jan 2025 09:37:20 +0800 "Huang, Ying" wrote: > > > 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. > > > > I think that we can do that with two weight arrays. > > > > > So I prefer to just have one IW array and no hidden state. > > > > Then, when we switch from manual to auto mode, where to find > > auto-generated weights? Re-calculate them? > > Even in manual mode, incoming bandwidth data is continuously stored. > This way, when a user does decide to switch back to auto mode later, > the system doesn't have to retrieve the bandwidth data all over again. > As for the auto-generated weights, they are re-calculated based solely > on the bandwidth data available. (I will note that re-calculating > the weights are very quick, see reduce_interleave_weights) > > Based on your description of the expected behavior, everything you > listed out is actually what currently happens in the one-layer system. > Switching from auto --> manual inherits the auto-generated weights, and > switching from manual --> auto wipes all previous user-stored data. > Piling on - the single-layer system is very bluntly simpler (one fewer array) with the exact same behavior. Therefore it's better (in my opinion). But this is all hidden from the user - so I don't care. If you (Ying) have strong feelings, we're happy to ship either. ~Gregory