From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: Jinchao Wang <wangjinchao600@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
x86@kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Ian Rogers <irogers@google.com>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v15 00/12] tracing: wprobe: x86: Add wprobe for watchpoint
Date: Sat, 12 Sep 2026 22:36:58 +0900 [thread overview]
Message-ID: <20260912223658.c4495241023f72e3cf48bf0c@kernel.org> (raw)
In-Reply-To: <307d6fd5-a8fa-4777-b513-9a8cce46f38a@gmail.com>
On Fri, 11 Sep 2026 15:27:41 +0800
Jinchao Wang <wangjinchao600@gmail.com> wrote:
> Hi Masami,
>
> I see the watch address update currently goes irq_work -> workqueue ->
> on_each_cpu(). I would like to discuss that path.
>
> The race window wprobe may be used to watch can be very narrow --
> sometimes it lives entirely inside a single function -- and the trigger
> does not always run in in_task() context. The current path defers the
> update to a work item, so by the time the debug registers are updated the
> window may already be gone.
>
> Now that we have modify_local_hw_breakpoint_addr(), the trigger could arm
> the local CPU directly and use smp_call_function_single_async() for the
> remote ones. That should improve the overlap between the watch and the window.
Hm, that is a good idea. Maybe we can check the current context and if
possible call modify_local_hw_breakcpoint_addr() directly for current
CPU core, and kick irq_work for other cores.
Does this make sense for you?
Thanks,
>
> What do you think?
>
> Thanks,
> Jinchao
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
prev parent reply other threads:[~2026-09-12 13:37 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-07 3:46 [PATCH v15 00/12] tracing: wprobe: x86: Add wprobe for watchpoint Masami Hiramatsu (Google)
2026-09-07 3:46 ` [PATCH v15 01/12] x86/mce: Fix hardware debug register corruption on task migration Masami Hiramatsu (Google)
2026-09-07 3:57 ` sashiko-bot
2026-09-07 3:46 ` [PATCH v15 02/12] x86/hw_breakpoints: Make DR7 updates NMI safe Masami Hiramatsu (Google)
2026-09-07 4:00 ` sashiko-bot
2026-09-07 3:46 ` [PATCH v15 03/12] x86/hw_breakpoints: Add arch_modify_local_hw_breakpoint_addr() API Masami Hiramatsu (Google)
2026-09-07 4:02 ` sashiko-bot
2026-09-07 3:47 ` [PATCH v15 04/12] HWBP: Add modify_local_hw_breakpoint_addr() API Masami Hiramatsu (Google)
2026-09-07 4:04 ` sashiko-bot
2026-09-07 3:47 ` [PATCH v15 05/12] tracing/wprobe: Add wprobe (watchpoint probe) trace event support Masami Hiramatsu (Google)
2026-09-07 4:15 ` sashiko-bot
2026-09-07 3:47 ` [PATCH v15 06/12] x86: hw_breakpoint: Add a kconfig to clarify when a breakpoint fires Masami Hiramatsu (Google)
2026-09-07 3:52 ` sashiko-bot
2026-09-07 3:47 ` [PATCH v15 07/12] selftests: tracing: Add a basic testcase for wprobe Masami Hiramatsu (Google)
2026-09-07 3:53 ` sashiko-bot
2026-09-07 3:47 ` [PATCH v15 08/12] selftests: tracing: Add syntax " Masami Hiramatsu (Google)
2026-09-07 3:58 ` sashiko-bot
2026-09-07 3:47 ` [PATCH v15 09/12] tracing/wprobe: Add set_wprobe and clear_wprobe event triggers Masami Hiramatsu (Google)
2026-09-07 4:10 ` sashiko-bot
2026-09-07 3:48 ` [PATCH v15 10/12] selftests: tracing: Add wprobe trigger testcase Masami Hiramatsu (Google)
2026-09-07 3:58 ` sashiko-bot
2026-09-07 3:48 ` [PATCH v15 11/12] tracing/wprobe: Support BTF typecast in fetchargs Masami Hiramatsu (Google)
2026-09-07 4:03 ` sashiko-bot
2026-09-07 3:48 ` [PATCH v15 12/12] tracing/wprobe: Support BTF struct offset resolution in set_wprobe trigger Masami Hiramatsu (Google)
2026-09-07 4:06 ` sashiko-bot
2026-09-11 7:27 ` [PATCH v15 00/12] tracing: wprobe: x86: Add wprobe for watchpoint Jinchao Wang
2026-09-12 13:36 ` Masami Hiramatsu [this message]
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