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[2003:cb:c707:9e00:fec0:7e96:15cb:742]) by smtp.gmail.com with ESMTPSA id b8-20020adff908000000b00223a50b1be8sm14023827wrr.50.2022.09.01.01.05.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 01 Sep 2022 01:05:05 -0700 (PDT) Message-ID: <404e947a-e1b2-0fae-8b4f-6f2e3ba6328d@redhat.com> Date: Thu, 1 Sep 2022 10:05:03 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 Content-Language: en-US To: Kent Overstreet , Michal Hocko Cc: Mel Gorman , Peter Zijlstra , Suren Baghdasaryan , akpm@linux-foundation.org, vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, void@manifault.com, juri.lelli@redhat.com, ldufour@linux.ibm.com, peterx@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, changbin.du@intel.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, arnd@arndb.de, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-mm@kvack.org, iommu@lists.linux.dev, kasan-dev@googlegroups.com, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220830214919.53220-1-surenb@google.com> <20220831084230.3ti3vitrzhzsu3fs@moria.home.lan> <20220831101948.f3etturccmp5ovkl@suse.de> <20220831190154.qdlsxfamans3ya5j@moria.home.lan> From: David Hildenbrand Organization: Red Hat Subject: Re: [RFC PATCH 00/30] Code tagging framework and applications In-Reply-To: <20220831190154.qdlsxfamans3ya5j@moria.home.lan> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org On 31.08.22 21:01, Kent Overstreet wrote: > On Wed, Aug 31, 2022 at 12:47:32PM +0200, Michal Hocko wrote: >> On Wed 31-08-22 11:19:48, Mel Gorman wrote: >>> Whatever asking for an explanation as to why equivalent functionality >>> cannot not be created from ftrace/kprobe/eBPF/whatever is reasonable. >> >> Fully agreed and this is especially true for a change this size >> 77 files changed, 3406 insertions(+), 703 deletions(-) > > In the case of memory allocation accounting, you flat cannot do this with ftrace > - you could maybe do a janky version that isn't fully accurate, much slower, > more complicated for the developer to understand and debug and more complicated > for the end user. > > But please, I invite anyone who's actually been doing this with ftrace to > demonstrate otherwise. > > Ftrace just isn't the right tool for the job here - we're talking about adding > per callsite accounting to some of the fastest fast paths in the kernel. > > And the size of the changes for memory allocation accounting are much more > reasonable: > 33 files changed, 623 insertions(+), 99 deletions(-) > > The code tagging library should exist anyways, it's been open coded half a dozen > times in the kernel already. Hi Kent, independent of the other discussions, if it's open coded already, does it make sense to factor that already-open-coded part out independently of the remainder of the full series here? [I didn't immediately spot if this series also attempts already to replace that open-coded part] -- Thanks, David / dhildenb