From: Steven Rostedt <rostedt@goodmis.org>
To: Alexei Starovoitov <ast@plumgrid.com>
Cc: Namhyung Kim <namhyung@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Jiri Olsa <jolsa@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
Daniel Borkmann <dborkman@redhat.com>,
Hannes Frederic Sowa <hannes@stressinduktion.org>,
Brendan Gregg <brendan.d.gregg@gmail.com>,
Linux API <linux-api@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH tip 0/9] tracing: attach eBPF programs to tracepoints/syscalls/kprobe
Date: Wed, 21 Jan 2015 20:56:43 -0500 [thread overview]
Message-ID: <20150121205643.4d8a3516@gandalf.local.home> (raw)
In-Reply-To: <CAMEtUux8v2LDtLcgpT9hCvJgnrCwT2fkzsSvAPFSuEUx+itxyQ@mail.gmail.com>
On Wed, 21 Jan 2015 17:49:08 -0800
Alexei Starovoitov <ast@plumgrid.com> wrote:
> > This also makes it keeping events in the soft-disabled state.
>
> I was never able to figure out the use case for soft-disabled state.
> Probably historical before static_key was done.
No, it's not historical at all. The "soft-disable" is a way to enable
from any context. You can't enable a static key from NMI or interrupt
context, but you can enable a "soft-disable" there.
As you can enable or disable events from any function that the function
tracer may trace, I needed a way to enable them (make the tracepoint
active), but do nothing until something else turns them on.
-- Steve
next prev parent reply other threads:[~2015-01-22 1:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-22 1:49 Alexei Starovoitov
2015-01-22 1:56 ` Steven Rostedt [this message]
2015-01-22 2:13 ` Alexei Starovoitov
-- strict thread matches above, loose matches on Subject: below --
2015-01-16 18:57 Alexei Starovoitov
2015-01-22 1:03 ` Namhyung Kim
2015-01-16 4:16 Alexei Starovoitov
2015-01-16 15:02 ` Steven Rostedt
2015-01-19 9:52 ` Masami Hiramatsu
2015-01-19 20:48 ` Alexei Starovoitov
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