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imf01.hostedemail.com; none Received: from omf19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id B0F07C01D8; Thu, 18 Sep 2025 14:46:59 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf19.hostedemail.com (Postfix) with ESMTPA id 64C5F20026; Thu, 18 Sep 2025 14:46:52 +0000 (UTC) Date: Thu, 18 Sep 2025 10:48:00 -0400 From: Steven Rostedt To: Pedro Falcato Cc: Kalesh Singh , akpm@linux-foundation.org, minchan@kernel.org, lorenzo.stoakes@oracle.com, david@redhat.com, Liam.Howlett@oracle.com, rppt@kernel.org, kernel-team@android.com, android-mm@google.com, Alexander Viro , Christian Brauner , Jan Kara , Kees Cook , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Masami Hiramatsu , Mathieu Desnoyers , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , Jann Horn , Shuah Khan , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v2 7/7] mm/tracing: introduce max_vma_count_exceeded trace event Message-ID: <20250918104800.18682dcb@gandalf.local.home> In-Reply-To: <6x64jf7szyy52gug6qoixhhjq6vsrcqpozqj4ambsehh2jprj2@qeye6qevem4g> References: <20250915163838.631445-1-kaleshsingh@google.com> <20250915163838.631445-8-kaleshsingh@google.com> <20250915194158.472edea5@gandalf.local.home> <20250916115220.4a90c745@batman.local.home> <6x64jf7szyy52gug6qoixhhjq6vsrcqpozqj4ambsehh2jprj2@qeye6qevem4g> 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: U2FsdGVkX1/SPmSGyI4YAHSVF4EBeZrT9fbg8i0D60w= X-HE-Meta: U2FsdGVkX18tsNvH9bJDAyFjkOT2HA8ufoSMnckqu/PF/TMziwSBt6ub3HcDiaqCsBki4oHrVzGzWJgZN2TMafKiXzJFbwxNCtcijv/2L7usqvNreFB5cSMdaUx+V14enzYHmfTtY0OvIOF0Vg0J0H/94xSJuSaXEO3o9ykMJ9ZLZMPvBdMDl5Ws5yhHI1hjp0jHnj2XG/BfWP9WMn0eexomyP+td/1fW9VFhOT1kcCBFbRB7Afnn3ByETKi3Xwoxn8m29j0Wlt7indu64ikhql9bauxeS3wdvSqX0FmZNfQAUSyAjpZi3dQYT+/3fmf X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 3BB9240013 X-Stat-Signature: g59kxcztn1r7jr5dm8ogyzri6gb4wph7 X-HE-Tag-Orig: 1758206812-260855 X-Rspam-User: X-HE-Tag: 1758206823-829158 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 Thu, 18 Sep 2025 12:38:56 +0100 Pedro Falcato wrote: > Isn't the usual problem with that approach, that of static functions/static > inline functions? I was tracing through a problem a few months ago, and man > I really did think "wouldn't it be nice to have a tracepoint instead of fishing > around for kprobe spots". > > Not that I particularly think a tracepoint is super worth it in this case, but, > y'know. Yes, it would be useful. The issue is that tracepoints are not free. They do increase the I$ hit and take up memory. If you're going to inject a tracepoint somewhere, at least extract some useful information from that spot. If you can't think of anything to track, then it's not worth a tracepoint. If one really wants a way to track something, they could add a static branch that would call a function when enabled that could be traced. They would also need a way to enable that static branch. -- Steve