From: Ingo Molnar <mingo@elte.hu>
To: Roland McGrath <roland@redhat.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>,
lkml <linux-kernel@vger.kernel.org>,
systemtap <systemtap@sources.redhat.com>,
DLE <dle-develop@lists.sourceforge.net>
Subject: Re: [PATCH -tip 3/3] Add get_signal tracepoint
Date: Sat, 14 Nov 2009 00:12:00 -0000 [thread overview]
Message-ID: <20091114001020.GB24738@elte.hu> (raw)
In-Reply-To: <20091113235333.0E3CC15E8@magilla.sf.frob.com>
* Roland McGrath <roland@redhat.com> wrote:
> This is orthogonal to the core-dump tracepoint, I don't see why you
> call them a unified patch series.
>
> The proper name for this event is "signal delivery". But since the
> proper name for "send_signal" is "signal generation", I suppose "get"
> is analogously improper to the existing "send" tracepoint. ;-)
I'd suggest to add include/trace/events/signal.h and put these
tracepoints there.
> Especially if you call this "get" rather than "deliver", there is
> another place that should invoke this tracepoint (or perhaps a third
> one). sys_rt_sigtimedwait "gets" a signal without delivering it. In
> POSIX terminology this is called "accepting" the signal: the three
> things that can happen in the life of a signal are "generate",
> "deliver", and "accept". If you are trying to match up what happened
> to a signal generated by kill() or whatnot, then you want to notice
> both delivery and acceptance as the complementary event.
>
> (And again I have no clue why this signal stuff should be called
> "sched" at all.)
it shouldnt be called 'sched' - it should go into 'events/signal.h'.
But we also need fuller coverage than this. Coredumps and signal
delivery events are just a small part of all things signals, we also
want:
- signal generation events (send_sig*() variants)
- signal IPI/wakeup events
- signal loss events (queue overflow)
- [ optional: signal blocking/unblocking events ]
- [ optional: specific signal handler installation/deinstallation ]
That's what we generally require of new events: they should form a
coherent whole, a logical set of events that 'make sense' and explain
the workings of a subsystem on a given level of detail.
How finegrained or coarse the level of details is is an open question,
but if a given level of detail has been picked, we want completeness on
that level.
So for example in the list above, the '[ optional ]' events are
finegrained ones that could be left out of the initial version.
We've done this consistently for all subsystems that added tracepoints:
scheduling, locking, timers, workqueues, block IO, SLAB, IRQs, etc., and
we want a similar approach for newly covered subsystems (such as
signals) as well.
Thanks,
Ingo
next prev parent reply other threads:[~2009-11-14 0:12 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-13 22:52 [PATCH -tip 1/3] Pass mm->flags to binfmt core_dump for bitflag consistency Masami Hiramatsu
2009-11-13 22:52 ` [PATCH -tip 2/3] Add coredump tracepoint Masami Hiramatsu
2009-11-13 23:39 ` Roland McGrath
2009-11-14 0:00 ` Masami Hiramatsu
2009-11-14 0:02 ` Ingo Molnar
2009-11-14 0:06 ` Roland McGrath
2009-11-14 0:14 ` Ingo Molnar
2009-11-14 1:49 ` Roland McGrath
2009-11-14 0:26 ` Masami Hiramatsu
2009-11-13 22:52 ` [PATCH -tip 3/3] Add get_signal tracepoint Masami Hiramatsu
2009-11-13 23:53 ` Roland McGrath
2009-11-14 0:12 ` Ingo Molnar [this message]
2009-11-16 21:52 ` Masami Hiramatsu
2009-11-16 22:11 ` Roland McGrath
2009-11-16 22:40 ` Masami Hiramatsu
2009-11-16 23:01 ` Roland McGrath
2009-11-16 23:46 ` Masami Hiramatsu
2009-11-17 6:03 ` Ingo Molnar
2009-11-17 15:25 ` Masami Hiramatsu
2009-11-14 0:29 ` Masami Hiramatsu
2009-11-13 23:09 ` [PATCH -tip 1/3] Pass mm->flags to binfmt core_dump for bitflag consistency Andrew Morton
2009-11-13 23:25 ` Ingo Molnar
2009-11-13 23:45 ` Masami Hiramatsu
2009-11-13 23:16 ` Roland McGrath
2009-11-13 23:23 ` Ingo Molnar
2009-11-13 23:30 ` Roland McGrath
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