From: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
To: Yonghong Song <yhs@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Daniel Xu <dxu@dxuuu.xyz>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
Song Liu <songliubraving@fb.com>,
Andrii Nakryiko <andriin@fb.com>,
"mingo@redhat.com" <mingo@redhat.com>,
Alexei Starovoitov <ast@fb.com>,
"alexander.shishkin@linux.intel.com"
<alexander.shishkin@linux.intel.com>,
"jolsa@redhat.com" <jolsa@redhat.com>,
"namhyung@kernel.org" <namhyung@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [PATCH v3 bpf-next 1/4] tracing/probe: Add PERF_EVENT_IOC_QUERY_PROBE ioctl
Date: Wed, 21 Aug 2019 17:04:43 -0300 [thread overview]
Message-ID: <20190821200443.GH3929@kernel.org> (raw)
In-Reply-To: <5ecdcd72-255d-26d1-baf3-dc64498753c2@fb.com>
Em Wed, Aug 21, 2019 at 06:43:49PM +0000, Yonghong Song escreveu:
> On 8/21/19 11:31 AM, Peter Zijlstra wrote:
> > On Wed, Aug 21, 2019 at 04:54:47PM +0000, Yonghong Song wrote:
> >> A lot of bpf-based tracing programs uses maps to communicate and
> >> do not allocate ring buffer at all.
> >
> > So extending PERF_RECORD_LOST doesn't work. But PERF_FORMAT_LOST might
> > still work fine; but you get to implement it for all software events.
>
> Could you give more specifics about PERF_FORMAT_LOST? Googling
> "PERF_FORMAT_LOST" only yields two emails which we are discussing here :-(
Perhaps he's talking about using read(perf_event_fd, ...) after having set it
up with perf_event_attr.read_format with the-to-be-implemented
PERF_FORMAT_LOST bit?
Look at perf_read() and perf_read_one() in kernel/events/core.c.
- Arnaldo
next prev parent reply other threads:[~2019-08-21 20:04 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
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 [this message]
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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