From: "Daniel Xu" <dxu@dxuuu.xyz>
To: "Peter Zijlstra" <peterz@infradead.org>
Cc: <bpf@vger.kernel.org>, <songliubraving@fb.com>, <yhs@fb.com>,
<andriin@fb.com>, <mingo@redhat.com>, <acme@kernel.org>,
<ast@fb.com>, <alexander.shishkin@linux.intel.com>,
<jolsa@redhat.com>, <namhyung@kernel.org>,
<linux-kernel@vger.kernel.org>, <kernel-team@fb.com>
Subject: Re: [PATCH v3 bpf-next 1/4] tracing/probe: Add PERF_EVENT_IOC_QUERY_PROBE ioctl
Date: Tue, 20 Aug 2019 10:58:47 -0700 [thread overview]
Message-ID: <BWENHQJIN885.216UOYEIWNGFU@dlxu-fedora-R90QNFJV> (raw)
In-Reply-To: <20190820144503.GV2332@hirez.programming.kicks-ass.net>
Hi Peter,
On Tue Aug 20, 2019 at 4:45 PM Peter Zijlstra wrote:
> On Fri, Aug 16, 2019 at 03:31:46PM -0700, Daniel Xu wrote:
> > It's useful to know [uk]probe's nmissed and nhit stats. For example with
> > tracing tools, it's important to know when events may have been lost.
> > debugfs currently exposes a control file to get this information, but
> > it is not compatible with probes registered with the perf API.
>
> What is this nmissed and nhit stuff?
nmissed is the number of times the probe's handler should have been run
but didn't. nhit is the number of times the probes handler has run. I've
documented this information in the uapi header. If you'd like, I can put
it in the commit message too.
Daniel
next prev parent reply other threads:[~2019-08-20 17:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-16 22:31 [PATCH v3 bpf-next 0/4] tracing/probe: Add PERF_EVENT_IOC_QUERY_PROBE Daniel Xu
2019-08-16 22:31 ` [PATCH v3 bpf-next 1/4] tracing/probe: Add PERF_EVENT_IOC_QUERY_PROBE ioctl Daniel Xu
2019-08-19 18:22 ` kbuild test robot
2019-08-20 1:26 ` Alexei Starovoitov
2019-08-20 2:34 ` Daniel Xu
2019-08-20 2:52 ` Alexei Starovoitov
2019-08-20 2:04 ` kbuild test robot
2019-08-20 14:45 ` Peter Zijlstra
2019-08-20 17:58 ` Daniel Xu [this message]
2019-08-21 11:08 ` Peter Zijlstra
2019-08-21 16:54 ` Yonghong Song
2019-08-21 18:31 ` Peter Zijlstra
2019-08-21 18:43 ` Yonghong Song
2019-08-21 20:04 ` Arnaldo Carvalho de Melo
2019-08-22 7:47 ` Peter Zijlstra
2019-08-22 7:54 ` Song Liu
2019-08-22 9:05 ` Peter Zijlstra
2019-08-22 21:08 ` Daniel Xu
2019-08-21 20:07 ` Arnaldo Carvalho de Melo
2019-08-21 22:10 ` Yonghong Song
2019-08-16 22:31 ` [PATCH v3 bpf-next 2/4] libbpf: Add helpers to extract perf fd from bpf_link Daniel Xu
2019-08-19 17:45 ` Andrii Nakryiko
2019-08-19 21:30 ` Daniel Xu
2019-08-16 22:31 ` [PATCH v3 bpf-next 3/4] tracing/probe: Sync perf_event.h to tools Daniel Xu
2019-08-16 22:31 ` [PATCH v3 bpf-next 4/4] tracing/probe: Add self test for PERF_EVENT_IOC_QUERY_PROBE Daniel Xu
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