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cv=none; b=1xM8WEZIsgUhfbXV54MmIWLs5DR6setzS0P+nXEi5pF9TR9LWWMG2qnDnouGt+vLIrhd/2 0+YBi6rNfkENIjLQog6nhWnPC1hKKepqzs79t3F5yA67pcnN+LCdfAFymXi37zhdUeBtn7 ChzHSr1gwtQgNobvQILAEQyOZE/Kch0= Received: from omf20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 158CE1DE3B6; Mon, 27 Oct 2025 14:53:33 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf20.hostedemail.com (Postfix) with ESMTPA id 28FBC20028; Mon, 27 Oct 2025 14:53:28 +0000 (UTC) Date: Mon, 27 Oct 2025 10:54:03 -0400 From: Steven Rostedt To: Alex Markuze Cc: ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Liam.Howlett@oracle.com, akpm@linux-foundation.org, bsegall@google.com, david@redhat.com, dietmar.eggemann@arm.com, idryomov@gmail.com, mingo@redhat.com, juri.lelli@redhat.com, kees@kernel.org, lorenzo.stoakes@oracle.com, mgorman@suse.de, mhocko@suse.com, rppt@kernel.org, peterz@infradead.org, surenb@google.com, vschneid@redhat.com, vincent.guittot@linaro.org, vbabka@suse.cz, xiubli@redhat.com, Slava.Dubeyko@ibm.com Subject: Re: [RFC PATCH 0/5] BLOG: per-task logging contexts with Ceph consumer Message-ID: <20251027105403.2d020b8d@gandalf.local.home> In-Reply-To: References: <20251024084259.2359693-1-amarkuze@redhat.com> <20251024135301.0ed4b57d@gandalf.local.home> <20251025105944.1a04e518@batman.local.home> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX18QkOO9R21LVBrW4cwrEsvG40q+N7FRrKg= X-HE-Meta: U2FsdGVkX1/y2rxUidxPu/q4n8C0KJZeyG9NUfc267rFSYjiZBs19+cLFZ1Ce5eI25D7AtEIUV88ToUUjzXl12lsYbGAgOTQYwQg5nE7AyNBP1f7Bt2CIa4mybazVYojiJXsfpZEyBhhJuY8YYQW/U0XRduqJYyOMi4Xk3v9Mo1bW7ImUBopldJfQW9+NP+Moo18A+AzIZtEdv8wx0PpAiegJ9cvnQI705vJv4huyvM5eprVEIcCifuhhNtKcMV6hRz124rK2MjqUDdFccljiUkErq6KpbP2LYaxEaDSoqwcHaVp1KD7b3B6Zz26gXdoH4pIcwzKBvP09JRLCAVwIjFCzDQSEur7 X-HE-Tag-Orig: 1761576808-121962 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6FE491C000C X-Stat-Signature: btabxbh6rn4s9y75i8tsernxrkczhxfu X-Rspam-User: X-HE-Tag: 1761576815-503571 X-HE-Meta: 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 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 Sat, 25 Oct 2025 20:54:00 +0300 Alex Markuze wrote: > Please correct me if I am wrong, I was not aware that ftrace is used > by any kernel component as the default unstructured logger. > This is the point of BLog, having a low impact unstructured logger, > it's not always possible or easy to provide a debug kernel where > ftarce is both enabled and used for dumping logs. > Having an always-on binary logger facilitates better debuggability. > When anything happens, a client with BLog has the option to send a > large log file with their report. > An additional benefit is that each logging buffer is attached to the > associated tasks and the whole module has its own separate cyclical > log buffer. This looks like a very specific solution trying to be a little more generic. The more generic a solution becomes, the more "bloated" it becomes as well. That's the nature of tracers and loggers. Ftrace was designed to be very generic, and yes, it can be more bloated because of that. But it is also designed to be tuned down to be a highly efficient tracer. One that can be used in a production environment. Sure, if you enable every event, it will cause a noticeable overhead, but ftrace is designed to surgically pick which events should be enabled or not, keeping the overhead within the noise. Ftrace is more of an "infrastructure" than a tool. It provides access to trace almost every function , but you can use that same code to implement live kernel patching or BPF hooks to functions. The trace event and tracepoints are part of ftrace, and are used for things other than tracing. Perhaps it may be more suitable to make BLOG use the tracefs interface, then to create an entirely new interface based on debugfs (which BTW, a lot of production systems do not enable debugfs which is why ftrace uses its own tracefs that does not depend on it). -- Steve