From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 353E8C64991 for ; Thu, 1 Sep 2022 07:42:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232495AbiIAHmb (ORCPT ); Thu, 1 Sep 2022 03:42:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233178AbiIAHma (ORCPT ); Thu, 1 Sep 2022 03:42:30 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E5D51090AC; Thu, 1 Sep 2022 00:42:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=3R95H7o4Ps0Xt8Fb2RGRK8ftexUpMSTfRccKzarlwv8=; b=Eg80MMaySfuaV1ldmooclI5Nle IN65bkkyoGAXjGnjvZ9Dz97arRuZEhWCpPPCP1gw1nVSAW07lMYUIubOMxvASCB4vmoiTLGUvHrLv mnlyZtBunER3vltL8aBUMSfY4OGfxQTUnrR0dVTN+q9nK3Ed9aJ7y3lLrPOxju5X4dgv8lB4Rw2/S M4qKtJDbH/5MyAfn5zL3v6Z2qbXeFnlVENhNiHvxEi1N3ly1LlBYvlGl7CCxhftPsoPtvO9AoJQWv yv5KTzNibXIV76seLfOwEBNoqddr2AJkeDRRPmkEtfLxUWCG6NSjcEJWY7wpS3gtx9W2q+ItfapFU +bbvPyyg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1oTeqK-005qQi-Us; 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 447DF3004C7; 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: Precedence: bulk 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.