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Thu, 01 Sep 2022 07:42:29 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 42B7B3004C3; Thu, 1 Sep 2022 09:42:27 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 344DD2B871FC3; Thu, 1 Sep 2022 09:42:27 +0200 (CEST) Date: Thu, 1 Sep 2022 09:42:27 +0200 From: Peter Zijlstra To: Kent Overstreet Cc: Mel Gorman , Suren Baghdasaryan , akpm@linux-foundation.org, mhocko@suse.com, 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, david@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 Subject: Re: [RFC PATCH 00/30] Code tagging framework and applications Message-ID: References: <20220830214919.53220-1-surenb@google.com> <20220831084230.3ti3vitrzhzsu3fs@moria.home.lan> <20220831101948.f3etturccmp5ovkl@suse.de> <20220831155941.q5umplytbx6offku@moria.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=infradead.org header.s=desiato.20200630 header.b=cEnZuv0S; spf=none (imf28.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.92.199) smtp.mailfrom=peterz@infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662018171; a=rsa-sha256; cv=none; b=4cgTkNVuOeBiQ5NVJAPLSUkewX/aYr0AueirlOrqqcMetll4j3MTEcSUs/okquxIIdzTWK B8ZQ0q20x69rzrgn0NDBTGI9WT0hhgZvuG9isSqkrPIsW8zxw9rNW8ofOm9cCG831HlF6y 349iC3753unlH2xBT4Q+26GG3F0sSiA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662018171; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=3R95H7o4Ps0Xt8Fb2RGRK8ftexUpMSTfRccKzarlwv8=; b=VCjlhanb3lE6LxYlI3/uHJAZLwtSjlKqbyB4xrdT3q1Tg/ZShft7/O8rG8BoZooGQEnuIn cBeWYICf34ZttF6mZE/sLWn8MZ5qLEXYenemAftQQfsLJtY1jMZe1/Mps4HZUm1tGxz5gp sveNSlho46HmixNK/oWBIivla6pKXU0= X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 82303C003E X-Rspam-User: Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=infradead.org header.s=desiato.20200630 header.b=cEnZuv0S; spf=none (imf28.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.92.199) smtp.mailfrom=peterz@infradead.org; dmarc=none X-Stat-Signature: 4ckpmi7ek78494cu7fci86677oia1zjq X-HE-Tag: 1662018171-12989 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 Thu, Sep 01, 2022 at 09:05:36AM +0200, Peter Zijlstra wrote: > On Wed, Aug 31, 2022 at 11:59:41AM -0400, Kent Overstreet wrote: > > > Also, ftrace can drop events. Not really ideal if under system load your memory > > accounting numbers start to drift. > > You could attach custom handlers to tracepoints. If you were to replace > these unconditional code hooks of yours with tracepoints then you could > conditionally (say at boot) register custom handlers that do the > accounting you want. > > Nobody is mandating you use the ftrace ringbuffer to consume tracepoints. > Many people these days attach eBPF scripts to them and do whatever they > want. Look at kernel/trace/blktrace.c for a fine in-kernel !BFP example of this.