From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: 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>,
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>
Subject: Re: [PATCH v10 07/14] unwind_user/deferred: Make unwind deferral requests NMI-safe
Date: Thu, 19 Jun 2025 05:10:20 -0400 [thread overview]
Message-ID: <66B9E72C-4FDF-46DF-9231-BED06A6000D9@goodmis.org> (raw)
In-Reply-To: <20250619084813.GG1613633@noisy.programming.kicks-ass.net>
On June 19, 2025 4:48:13 AM EDT, Peter Zijlstra <peterz@infradead.org> wrote:
>On Thu, Jun 19, 2025 at 10:44:27AM +0200, Peter Zijlstra wrote:
>
>> Luckily, x86 dropped support for !CMPXCHG8B right along with !TSC. So on
>> x86 we good with timestamps, even on 32bit.
>
>Well, not entirely true, local_clock() is not guaranteed monotonic. So
>you might be in for quite a bit of hurt if you rely on that.
>
As long as it is monotonic per task. If it is not, then pretty much all tracers that use it are broken.
-- Steve
next prev parent reply other threads:[~2025-06-19 9:10 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-11 0:54 [PATCH v10 00/14] unwind_user: x86: Deferred unwinding infrastructure Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 01/14] unwind_user: Add user space unwinding API Steven Rostedt
2025-06-18 13:49 ` Peter Zijlstra
2025-06-11 0:54 ` [PATCH v10 02/14] unwind_user: Add frame pointer support Steven Rostedt
2025-06-18 13:52 ` Peter Zijlstra
2025-06-18 15:09 ` Steven Rostedt
2025-06-23 16:31 ` Indu Bhagat
2025-06-24 20:30 ` Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 03/14] unwind_user: Add compat mode " Steven Rostedt
2025-06-18 13:46 ` Peter Zijlstra
2025-06-18 15:10 ` Steven Rostedt
2025-06-18 17:52 ` Linus Torvalds
2025-06-18 18:37 ` Steven Rostedt
2025-06-18 13:47 ` Peter Zijlstra
2025-06-18 15:18 ` Steven Rostedt
2025-06-19 7:51 ` Peter Zijlstra
2025-06-19 8:39 ` Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 04/14] unwind_user/deferred: Add unwind_deferred_trace() Steven Rostedt
2025-06-18 13:54 ` Peter Zijlstra
2025-06-18 13:59 ` Peter Zijlstra
2025-06-18 15:20 ` Steven Rostedt
2025-06-18 16:26 ` Steven Rostedt
2025-06-18 14:01 ` Peter Zijlstra
2025-06-18 15:23 ` Steven Rostedt
2025-06-18 14:02 ` Peter Zijlstra
2025-06-18 15:29 ` Steven Rostedt
2025-06-19 7:54 ` Peter Zijlstra
2025-06-19 8:44 ` Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 05/14] unwind_user/deferred: Add unwind cache Steven Rostedt
2025-06-18 14:13 ` Peter Zijlstra
2025-06-18 15:33 ` Steven Rostedt
2025-06-19 7:56 ` Peter Zijlstra
2025-06-19 8:47 ` Steven Rostedt
2025-06-19 9:04 ` Peter Zijlstra
2025-06-19 9:12 ` Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 06/14] unwind_user/deferred: Add deferred unwinding interface Steven Rostedt
2025-06-18 14:20 ` Peter Zijlstra
2025-06-18 15:37 ` Steven Rostedt
2025-06-18 15:38 ` Steven Rostedt
2025-06-19 8:01 ` Peter Zijlstra
2025-06-19 8:49 ` Steven Rostedt
2025-06-18 18:46 ` Peter Zijlstra
2025-06-18 19:09 ` Steven Rostedt
2025-06-18 19:36 ` Steven Rostedt
2025-06-19 7:50 ` Peter Zijlstra
2025-06-19 8:56 ` Steven Rostedt
2025-06-19 9:11 ` Peter Zijlstra
2025-06-24 14:03 ` Steven Rostedt
2025-06-24 22:36 ` Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 07/14] unwind_user/deferred: Make unwind deferral requests NMI-safe Steven Rostedt
2025-06-19 8:34 ` Peter Zijlstra
2025-06-19 8:37 ` Steven Rostedt
2025-06-19 8:44 ` Peter Zijlstra
2025-06-19 8:48 ` Peter Zijlstra
2025-06-19 9:10 ` Steven Rostedt [this message]
2025-06-19 9:24 ` Peter Zijlstra
2025-06-19 8:57 ` Peter Zijlstra
2025-06-19 9:07 ` Steven Rostedt
2025-06-19 9:32 ` Peter Zijlstra
2025-06-19 9:34 ` Peter Zijlstra
2025-06-19 9:42 ` Steven Rostedt
2025-06-19 9:45 ` Peter Zijlstra
2025-06-19 10:19 ` Steven Rostedt
2025-06-19 10:39 ` Peter Zijlstra
2025-06-19 13:04 ` Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 08/14] unwind deferred: Use bitmask to determine which callbacks to call Steven Rostedt
2025-06-20 8:15 ` Peter Zijlstra
2025-06-24 14:55 ` Steven Rostedt
2025-06-24 15:00 ` Peter Zijlstra
2025-06-24 16:36 ` Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 09/14] unwind deferred: Use SRCU unwind_deferred_task_work() Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 10/14] unwind: Clear unwind_mask on exit back to user space Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 11/14] unwind: Finish up unwind when a task exits Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 12/14] unwind_user/x86: Enable frame pointer unwinding on x86 Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 13/14] perf/x86: Rename and move get_segment_base() and make it global Steven Rostedt
2025-06-11 0:54 ` [PATCH v10 14/14] unwind_user/x86: Enable compat mode frame pointer unwinding on x86 Steven Rostedt
2025-06-12 21:44 ` [PATCH v10 00/14] unwind_user: x86: Deferred unwinding infrastructure Andrii Nakryiko
2025-06-12 22:02 ` Josh Poimboeuf
2025-06-12 23:30 ` Andrii Nakryiko
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