From: Arnaldo Carvalho de Melo <acme@redhat.com>
To: Stephane Eranian <eranian@google.com>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
mingo@elte.hu, jolsa@redhat.com, namhyung@kernel.org
Subject: Re: [PATCH v2] perf record: fix priv level with branch sampling for paranoid=2
Date: Mon, 23 Sep 2019 11:17:38 -0300 [thread overview]
Message-ID: <20190923141738.GB3617@redhat.com> (raw)
In-Reply-To: <20190923140345.GA3617@redhat.com>
Em Mon, Sep 23, 2019 at 11:03:45AM -0300, Arnaldo Carvalho de Melo escreveu:
> Thanks, tested added Jiri's Acked-by, applied, added this note:
>
> Committer testing:
>
> After aplying the patch we get:
>
> [acme@quaco ~]$ perf record -b -e cycles date
> WARNING: Kernel address maps (/proc/{kallsyms,modules}) are restricted,
> check /proc/sys/kernel/kptr_restrict and /proc/sys/kernel/perf_event_paranoid.
>
> Samples in kernel functions may not be resolved if a suitable vmlinux
> file is not found in the buildid cache or in the vmlinux path.
>
> Samples in kernel modules won't be resolved at all.
>
> If some relocation was applied (e.g. kexec) symbols may be misresolved
> even with a suitable vmlinux or kallsyms file.
>
> Mon 23 Sep 2019 11:00:59 AM -03
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.005 MB perf.data (14 samples) ]
> [acme@quaco ~]$ perf evlist -v
> cycles:u: size: 112, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|PERIOD|BRANCH_STACK, read_format: ID, disabled: 1, inherit: 1, exclude_kernel: 1, exclude_hv: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1, branch_sample_type: ANY
> [acme@quaco ~]$
>
> That warning about restricted kernel maps will be suppressed in a follow
> up patch, as perf_event_attr.exclude_kernel is set, i.e. no samples for
> the kernel will be taken and thus no need for those maps
Its there:
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/commit/?h=perf/core&id=c8b567c8a96a35acff746b1eef6f859e2a9fc195
- Arnaldo
prev parent reply other threads:[~2019-09-23 14:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-20 23:03 [PATCH v2] perf record: fix priv level with branch sampling for paranoid=2 Stephane Eranian
2019-09-23 14:03 ` Arnaldo Carvalho de Melo
2019-09-23 14:17 ` Arnaldo Carvalho de Melo [this message]
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