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b=MVCXXo8qbijgMJiVJjdi+tOp7fKoZMjcNnpd/ZKA0NTQOTF0cIpopgNnS/WcLD/iH Dx5AALPAKSLi+txuOy8+siut8dRp27+Sea26gpN1WB4mFiW1aUMe2tp/lsn4A/4MTp tab9Rp4F5tZhRhfSTTa/+tMTj3ZJMTRVhXThRKwksvYqcQ51gUrHS4x/ZrGeW9s1tq NP34DKw/z5hg1bb22Xw5k0/6RIaYgP9d7vjikZXyZtG6ikohGl7YgMtN5jODkiqqGn HdqqHL45uRz9n9PxHm5fWNRLSqXggYEAVYipYC+Vdw6WjEgr9PGbHE9w157zhTlVC9 PIdijT129JaXQ== Date: Fri, 3 Jan 2025 12:08:39 -1000 From: Tejun Heo To: JP Kobryn Cc: shakeel.butt@linux.dev, mhocko@kernel.org, hannes@cmpxchg.org, yosryahmed@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, cgroups@vger.kernel.org Subject: Re: [RFC PATCH 0/9 v2] cgroup: separate per-subsystem rstat trees Message-ID: References: <20250103015020.78547-1-inwardvessel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250103015020.78547-1-inwardvessel@gmail.com> X-Rspamd-Queue-Id: 3C52414000E X-Stat-Signature: gosy7dz54co9wxtnb3assjwqzbe35ago X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1735942122-275839 X-HE-Meta: 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 4lo+U81M wE569pJ3UXzz3sjnaDZ9FjI9zValZuEk34ywAd4PW5lt0UrSPPzL/+wTEbnrI4mejerAzw9tZlw9NWFtWh89FYo8N7HOkcmfFGYCnmYajTviWdeh9baomXTdqwjBx4VUpP+n3yJ31YLMJViER1LRBvRu1y9f4bT5Be85l/rKVTjn1yUkQS0aQCi/DIrZmb7PhOAaH0X1uoT+eMqNapPet7toJoA== 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: Hello, On Thu, Jan 02, 2025 at 05:50:11PM -0800, JP Kobryn wrote: ... > I reached a point where this started to feel stable in my local testing, so I > wanted to share and get feedback on this approach. The rationale for using one tree to track all subsystems was that if one subsys has been active (e.g. memory), it's likely that other subsyses have been active too (e.g. cpu) and thus we might as well flush the whole thing together. The approach can be useful for reducing the amount of work done when e.g. there are a lot of cgroups which are only active periodically but has drawbacks when one subsystem's stats are read a lot more actively than others as you pointed out. Intuitions go only so far and it's difficult to judge whether splitting the trees would be a good idea without data. Can you please provide some numbers along with rationales for the test setups? Thanks. -- tejun