From: Frederic Weisbecker <frederic@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Alexei Starovoitov <ast@kernel.org>, Yonghong Song <yhs@fb.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>,
bpf@vger.kernel.org, Joel Fernandes <joel@joelfernandes.org>,
linux-trace-kernel@vger.kernel.org,
Michael Jeanson <mjeanson@efficios.com>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH v1 3/8] tracing/perf: guard syscall probe with preempt_notrace
Date: Fri, 4 Oct 2024 02:17:28 +0200 [thread overview]
Message-ID: <Zv80GJWwUVwPwvgf@pavilion.home> (raw)
In-Reply-To: <20241003182508.6ca76abc@gandalf.local.home>
Le Thu, Oct 03, 2024 at 06:25:08PM -0400, Steven Rostedt a écrit :
> On Thu, 3 Oct 2024 11:16:33 -0400
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
>
> > In preparation for allowing system call enter/exit instrumentation to
> > handle page faults, make sure that perf can handle this change by
> > explicitly disabling preemption within the perf system call tracepoint
> > probes to respect the current expectations within perf ring buffer code.
> >
> > This change does not yet allow perf to take page faults per se within
> > its probe, but allows its existing probes to adapt to the upcoming
> > change.
>
> Frederic,
>
> Does the perf ring buffer expect preemption to be disabled when used?
>
> In other words, is this patch needed?
At least the trace events perf callback requires that because it uses
a per cpu buffer (see perf_trace_buf_alloc()).
Thanks.
next prev parent reply other threads:[~2024-10-04 0:17 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-03 15:16 [PATCH v1 0/8] tracing: Allow system call tracepoints to handle page faults Mathieu Desnoyers
2024-10-03 15:16 ` [PATCH v1 1/8] tracing: Declare system call tracepoints with TRACE_EVENT_SYSCALL Mathieu Desnoyers
2024-10-03 21:32 ` Steven Rostedt
2024-10-04 0:15 ` Mathieu Desnoyers
2024-10-04 1:06 ` Steven Rostedt
2024-10-04 1:34 ` Mathieu Desnoyers
2024-10-04 10:34 ` kernel test robot
2024-10-03 15:16 ` [PATCH v1 2/8] tracing/ftrace: guard syscall probe with preempt_notrace Mathieu Desnoyers
2024-10-03 22:23 ` Steven Rostedt
2024-10-04 0:26 ` Mathieu Desnoyers
2024-10-04 1:04 ` Steven Rostedt
2024-10-04 1:33 ` Mathieu Desnoyers
2024-10-04 13:26 ` Steven Rostedt
2024-10-04 14:18 ` Mathieu Desnoyers
2024-10-04 14:45 ` Steven Rostedt
2024-10-04 14:19 ` Mathieu Desnoyers
2024-10-04 14:52 ` Steven Rostedt
2024-10-04 14:51 ` Mathieu Desnoyers
2024-10-04 20:04 ` Andrii Nakryiko
2024-10-04 20:59 ` Steven Rostedt
2024-10-03 15:16 ` [PATCH v1 3/8] tracing/perf: " Mathieu Desnoyers
2024-10-03 22:25 ` Steven Rostedt
2024-10-04 0:17 ` Frederic Weisbecker [this message]
2024-10-03 15:16 ` [PATCH v1 4/8] tracing/bpf: " Mathieu Desnoyers
2024-10-03 22:26 ` Steven Rostedt
2024-10-03 23:05 ` Alexei Starovoitov
2024-10-04 0:30 ` Mathieu Desnoyers
2024-10-04 1:28 ` Mathieu Desnoyers
2024-10-03 15:16 ` [PATCH v1 5/8] tracing: Allow system call tracepoints to handle page faults Mathieu Desnoyers
2024-10-03 22:29 ` Steven Rostedt
2024-10-04 0:35 ` Mathieu Desnoyers
2024-10-03 15:16 ` [PATCH v1 6/8] tracing/ftrace: Add might_fault check to syscall probes Mathieu Desnoyers
2024-10-03 22:36 ` Steven Rostedt
2024-10-04 0:11 ` Mathieu Desnoyers
2024-10-03 15:16 ` [PATCH v1 7/8] tracing/perf: " Mathieu Desnoyers
2024-10-03 22:37 ` Steven Rostedt
2024-10-04 0:12 ` Mathieu Desnoyers
2024-10-03 15:16 ` [PATCH v1 8/8] tracing/bpf: " Mathieu Desnoyers
2024-10-03 22:38 ` Steven Rostedt
2024-10-04 0:13 ` Mathieu Desnoyers
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