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Wed, 03 May 2023 11:40:09 -0700 (PDT) Received: from localhost ([2620:10d:c090:400::5:6454]) by smtp.gmail.com with ESMTPSA id u22-20020a634556000000b005287b22ea8esm12540790pgk.88.2023.05.03.11.40.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 May 2023 11:40:08 -0700 (PDT) Date: Wed, 3 May 2023 08:40:07 -1000 From: Tejun Heo To: Johannes Weiner Cc: Kent Overstreet , Michal Hocko , Suren Baghdasaryan , akpm@linux-foundation.org, vbabka@suse.cz, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, corbet@lwn.net, void@manifault.com, peterz@infradead.org, juri.lelli@redhat.com, ldufour@linux.ibm.com, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, dennis@kernel.org, muchun.song@linux.dev, rppt@kernel.org, paulmck@kernel.org, pasha.tatashin@soleen.com, yosryahmed@google.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, andreyknvl@gmail.com, keescook@chromium.org, ndesaulniers@google.com, gregkh@linuxfoundation.org, ebiggers@google.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, dvyukov@google.com, shakeelb@google.com, songmuchun@bytedance.com, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, cgroups@vger.kernel.org, Alexei Starovoitov , Andrii Nakryiko Subject: Re: [PATCH 00/40] Memory allocation profiling Message-ID: References: <20230501165450.15352-1-surenb@google.com> <20230503180726.GA196054@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: On Wed, May 03, 2023 at 08:19:24AM -1000, Tejun Heo wrote: > > Taking a step back though, given the multitude of allocation sites in > > the kernel, it's a bit odd that the only accounting we do is the tiny > > fraction of voluntary vmstat/meminfo reporting. We try to cover the > > biggest consumers with this of course, but it's always going to be > > incomplete and is maintenance overhead too. There are on average > > several gigabytes in unknown memory (total - known vmstats) on our > > machines. It's difficult to detect regressions easily. And it's per > > definition the unexpected cornercases that are the trickiest to track > > down. So it might be doable with BPF, but it does feel like the kernel > > should do a better job of tracking out of the box and without > > requiring too much plumbing and somewhat fragile kernel allocation API > > tracking and probing from userspace. > > Yeah, easy / default visibility argument does make sense to me. So, a bit of addition here. If this is the thrust, the debugfs part seems rather redundant, right? That's trivially obtainable with tracing / bpf and in a more flexible and performant manner. Also, are we happy with recording just single depth for persistent tracking? Thanks. -- tejun