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From: Kent Overstreet To: David Wang <00107082@163.com> Cc: Suren Baghdasaryan , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Add accumulated call counter for memory allocation profiling Message-ID: References: <20240617153250.9079-1-00107082@163.com> <13c19bd1.2c49.1906c1ac5bf.Coremail.00107082@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <13c19bd1.2c49.1906c1ac5bf.Coremail.00107082@163.com> X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: D8A0F40009 X-Stat-Signature: 3gnzi37ru5k5yb8hbkctcmijr5qmgsh7 X-HE-Tag: 1719871135-688663 X-HE-Meta: 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 xB/PCZpH LXfw+57n95ec1yHDEugXSf13VljZlwB/+EwUQafUK+NZBzDNeinmOIFQUXWwfBLl6GJShmfpVDQ93SKjIAA2qwaeGx7yhvHF51K5do7EuN30Zd/0eNs7a5kCXZIJJK00ApCkcChuJC84OAG7IjH86CuqTypTheoVGtsCZCb53tFF6sVbl3y3iq4JM5DDyzq6SkBasicMFwaXj+FHa/37rZZu0jfiuiOCClaYo1sW2zlokdoZoSpCCjO8epznae46YM1aMM1gq5T6j6tSBgg5/qZF4VA== 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 Mon, Jul 01, 2024 at 10:23:32AM GMT, David Wang wrote: > HI Suren, > > At 2024-07-01 03:33:14, "Suren Baghdasaryan" wrote: > >On Mon, Jun 17, 2024 at 8:33 AM David Wang <00107082@163.com> wrote: > >> > >> Accumulated call counter can be used to evaluate rate > >> of memory allocation via delta(counters)/delta(time). > >> This metrics can help analysis performance behaviours, > >> e.g. tuning cache size, etc. > > > >Sorry for the delay, David. > >IIUC with this counter you can identify the number of allocations ever > >made from a specific code location. Could you please clarify the usage > >a bit more? Is the goal to see which locations are the most active and > >the rate at which allocations are made there? How will that > >information be used? > > Cumulative counters can be sampled with timestamp, say at T1, a monitoring tool got a sample value V1, > then after sampling interval, at T2, got a sample value V2. Then the average rate of allocation can be evaluated > via (V2-V1)/(T2-T1). (The accuracy depends on sampling interval) > > This information "may" help identify where the memory allocation is unnecessary frequent, > and gain some better performance by making less memory allocation . > The performance "gain" is just a guess, I do not have a valid example. Easier to just run perf...