From: "Daniel Xu" <dxu@dxuuu.xyz>
To: "Andrii Nakryiko" <andrii.nakryiko@gmail.com>
Cc: "Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"Andrii Nakryiko" <andriin@fb.com>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"Kernel Team" <kernel-team@fb.com>
Subject: Re: [PATCH 0/3] Add PERF_EVENT_IOC_QUERY_KPROBE ioctl
Date: Thu, 08 Aug 2019 15:32:24 -0700 [thread overview]
Message-ID: <d97ee4ce-06b6-45a6-a999-6e654e0236e4@www.fastmail.com> (raw)
In-Reply-To: <CAEf4BzbTeZLpMT0d0CchYZnMTUj3yYUxi4M0Ki6Urgo8_Lqz4w@mail.gmail.com>
On Wed, Aug 7, 2019, at 12:03 PM, Andrii Nakryiko wrote:
> On Tue, Aug 6, 2019 at 4:39 PM Daniel Xu <dxu@dxuuu.xyz> wrote:
> >
> > It's useful to know kprobe's nmissed and nhit stats. For example with
>
> Is nmissed/nhit kprobe-specific? What about tracepoints and raw
> tracepoints, do they have something similar or they can never be
> missed? At least nhit still seems useful, so would be nice to have
> ability to get that with the same API, is it possible?
>
I'm still trying to grok all the tracepoint/ftrace machinery, but it appears
to me like it is kprobe/uprobe specific. My guess is that b/c tracepoints are
inline (and don't require trapping interrupts), it cannot really "miss".
This brings up a good point, though. I think we want the same querying
functionality for uprobes so it might be worthwhile to make this API generic.
Something like PERF_EVENT_IOC_QUERY_PROBE so we can later add in
uprobe stats. And maybe tracepoint if it makes sense.
Thoughts?
next prev parent reply other threads:[~2019-08-08 22:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-06 23:38 [PATCH 0/3] Add PERF_EVENT_IOC_QUERY_KPROBE ioctl Daniel Xu
2019-08-07 5:24 ` Yonghong Song
2019-08-07 17:49 ` Song Liu
2019-08-07 19:03 ` Andrii Nakryiko
2019-08-08 22:32 ` Daniel Xu [this message]
2019-08-09 17:18 ` Andrii Nakryiko
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