From: Dmitry Vyukov <dvyukov@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: 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>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Will Deacon <will@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Matt Morehouse <mascasa@google.com>
Subject: Re: Process-wide watchpoints
Date: Thu, 4 Feb 2021 09:10:11 +0100 [thread overview]
Message-ID: <CACT4Y+btOt5QFKH9Q=81EnpDHoidJUHE2s0oZ8v65t-b__awuw@mail.gmail.com> (raw)
In-Reply-To: <YBqnAYVdNM4uyGny@hirez.programming.kicks-ass.net>
On Wed, Feb 3, 2021 at 2:37 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, Feb 03, 2021 at 01:49:56PM +0100, Dmitry Vyukov wrote:
> > On Wed, Feb 3, 2021 at 1:29 PM Peter Zijlstra <peterz@infradead.org> wrote:
> > >
> > > On Mon, Feb 01, 2021 at 09:50:20AM +0100, Dmitry Vyukov wrote:
> > > > Or, alternatively would it be reasonable for perf to generate SIGTRAP
> > > > directly on watchpoint hit (like ptrace does)? That's what I am
> > > > ultimately trying to do by attaching a bpf program.
> > >
> > > Perf should be able to generate signals, The perf_event_open manpage
> > > lists two ways of trigering signals. The second way doesn't work for
> > > you, due to it not working on inherited counters, but would the first
> > > work?
> > >
> > > That is, set attr::wakeup_events and fcntl(F_SETSIG).
> >
> > The problem is that this sends a signal to the fd owner rather than
> > the thread that hit the breakpoint. At least that's what happened in
> > our tests. We would like to send a signal to the thread that hit the
> > breakpoint.
>
> Ah indeed.. all of this was aimed at self-monitoring.
>
> Letting perf send a signal to the monitored task is intrusive.. let me
> think on that.
I was thinking of something very similar to that bpf_send_signal that
delays sending to exit from irq:
https://elixir.bootlin.com/linux/latest/source/kernel/trace/bpf_trace.c#L1091
next prev parent reply other threads:[~2021-02-04 8:11 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 7:46 Process-wide watchpoints Dmitry Vyukov
2020-11-12 10:31 ` Peter Zijlstra
2020-11-12 10:43 ` Dmitry Vyukov
[not found] ` <CACT4Y+bW1gpv8bz0vswaVUt-OB07oJ3NBeTi+vchAe8TTWK+mg@mail.gmail.com>
[not found] ` <CACT4Y+ZsKXfAxrzJGQc5mJ+QiP5sAw7zKWtciS+07qZzSf33mw@mail.gmail.com>
2021-02-01 8:50 ` Dmitry Vyukov
2021-02-03 12:29 ` Peter Zijlstra
2021-02-03 12:49 ` Dmitry Vyukov
2021-02-03 12:50 ` Dmitry Vyukov
2021-02-03 13:37 ` Peter Zijlstra
2021-02-04 8:10 ` Dmitry Vyukov [this message]
2021-02-04 9:38 ` Peter Zijlstra
2021-02-04 9:54 ` Dmitry Vyukov
2021-02-04 12:09 ` Peter Zijlstra
2021-02-04 12:53 ` Dmitry Vyukov
2021-02-04 13:10 ` Peter Zijlstra
2021-02-04 13:35 ` Dmitry Vyukov
2021-02-04 13:45 ` Peter Zijlstra
2021-02-04 14:59 ` Peter Zijlstra
2021-02-04 13:33 ` Peter Zijlstra
2021-02-04 13:37 ` Dmitry Vyukov
2021-02-04 13:06 ` Peter Zijlstra
2021-02-03 5:38 ` Namhyung Kim
2021-02-04 8:10 ` Dmitry Vyukov
2021-02-03 12:22 ` Peter Zijlstra
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