From: Paul Clarke <pc@us.ibm.com>
To: Tony Jones <tonyj@suse.de>, linux-perf-users@vger.kernel.org
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf tools: update docs regarding kernel/user space unwinding
Date: Thu, 26 Mar 2020 16:32:26 -0500 [thread overview]
Message-ID: <38ba2caa-dadd-52c4-c6ea-5e01b7e59ee2@us.ibm.com> (raw)
In-Reply-To: <20200325164053.10177-1-tonyj@suse.de>
On 3/25/20 11:40 AM, Tony Jones wrote:
> The method of unwinding for kernel space is defined by the kernel config,
> not by the value of --call-graph. Improve the documentation to reflect
> this.
> diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt
> index 8ead55593984..88cf35fbedc5 100644
> --- a/tools/perf/Documentation/perf-config.txt
> +++ b/tools/perf/Documentation/perf-config.txt
> @@ -405,14 +405,16 @@ ui.*::
> This option is only applied to TUI.
>
> call-graph.*::
> - When sub-commands 'top' and 'report' work with -g/—-children
> - there're options in control of call-graph.
> + The following controls the handling of call-graphs (obtained via the
> + -g/--callgraph options).
>
> call-graph.record-mode::
> - The record-mode can be 'fp' (frame pointer), 'dwarf' and 'lbr'.
> - The value of 'dwarf' is effective only if perf detect needed library
> - (libunwind or a recent version of libdw).
> - 'lbr' only work for cpus that support it.
> + The mode for user space can be 'fp' (frame pointer), 'dwarf'
> + and 'lbr'. The value 'dwarf' is effective only if libunwind
> + (or a recent version of libdw) is present on the system;
> + the value 'lbr' only works for certain cpus. The method for
> + kernel space is controlled not by this option but by the
> + kernel config (CONFIG_UNWINDER_*).
Your changes are just copying the old text, so this isn't a criticism of your patches.
Do we have information to replace "a recent version of libdw", which will quickly get stale?
PC
next prev parent reply other threads:[~2020-03-26 21:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 16:40 [PATCH] perf tools: update docs regarding kernel/user space unwinding Tony Jones
2020-03-25 19:17 ` Arnaldo Carvalho de Melo
2020-03-25 19:29 ` Tony Jones
2020-03-26 21:32 ` Paul Clarke [this message]
2020-03-27 20:09 ` Tony Jones
2020-03-27 20:17 ` Arnaldo Melo
2020-03-27 20:33 ` Tony Jones
2020-04-04 8:41 ` [tip: perf/urgent] perf callchain: Update " tip-bot2 for Tony Jones
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