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From: Steven Rostedt <rostedt@goodmis.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@kernel.org>,
	linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
	bpf@vger.kernel.org, x86@kernel.org,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andrii Nakryiko <andrii@kernel.org>,
	Indu Bhagat <indu.bhagat@oracle.com>,
	"Jose E. Marchesi" <jemarch@gnu.org>,
	Beau Belgrave <beaub@linux.microsoft.com>,
	Jens Remus <jremus@linux.ibm.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>, Florian Weimer <fweimer@redhat.com>,
	Sam James <sam@gentoo.org>
Subject: Re: [PATCH v14 09/12] unwind deferred: Use SRCU unwind_deferred_task_work()
Date: Thu, 17 Jul 2025 12:10:10 -0400	[thread overview]
Message-ID: <20250717121010.4246366a@batman.local.home> (raw)
In-Reply-To: <41c204c0-eabc-4f4f-93f4-2568e2f962a9@paulmck-laptop>

On Thu, 17 Jul 2025 08:48:40 -0700
"Paul E. McKenney" <paulmck@kernel.org> wrote:

> So if there is some reason that you absolutely cannot immediately convert
> to SRCU-fast, let's please discuss.

There's two reasons I wouldn't add it immediately.

One, is the guard(srcu_fast) isn't in mainline yet. I would either need
to open code it, or play the tricks of basing code off your tree.

Two, I'm still grasping at the concept of srcu_fast (and srcu_lite for
that matter), where I rather be slow and safe than optimize and be
unsafe. The code where this is used may be faulting in user space
memory, so it doesn't need the micro-optimizations now.

-- Steve

  reply	other threads:[~2025-07-17 16:10 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-17  0:49 [PATCH v14 00/12] unwind_user: x86: Deferred unwinding infrastructure Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 01/12] unwind_user: Add user space unwinding API with frame pointer support Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 02/12] unwind_user/deferred: Add unwind_user_faultable() Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 03/12] unwind_user/deferred: Add unwind cache Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 04/12] unwind_user/deferred: Add deferred unwinding interface Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 05/12] unwind_user/deferred: Make unwind deferral requests NMI-safe Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 06/12] unwind deferred: Use bitmask to determine which callbacks to call Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 07/12] unwind deferred: Add unwind_completed mask to stop spurious callbacks Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 08/12] unwind: Add USED bit to only have one conditional on way back to user space Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 09/12] unwind deferred: Use SRCU unwind_deferred_task_work() Steven Rostedt
2025-07-17  4:43   ` Paul E. McKenney
2025-07-17 12:25     ` Steven Rostedt
2025-07-17 15:48       ` Paul E. McKenney
2025-07-17 16:10         ` Steven Rostedt [this message]
2025-07-17 16:27           ` Paul E. McKenney
2025-07-17 16:38             ` Steven Rostedt
2025-07-17 16:54               ` Paul E. McKenney
2025-07-17  0:49 ` [PATCH v14 10/12] unwind: Finish up unwind when a task exits Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 11/12] unwind_user/x86: Enable frame pointer unwinding on x86 Steven Rostedt
2025-07-17  0:49 ` [PATCH v14 12/12] unwind deferred/x86: Do not defer stack tracing for compat tasks Steven Rostedt
2025-07-17  0:51 ` [PATCH v14 00/12] unwind_user: x86: Deferred unwinding infrastructure Steven Rostedt

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