linux-kernel - Re: [PATCH] perf probe: Ignore vmlinux build-id when offline vmlinux and dry-run used

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Message-Id: <20170126113743.2abec2b978377e31a450334b@kernel.org>
Date:   Thu, 26 Jan 2017 11:37:43 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Josh Hunt <johunt@...mai.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        linux-kernel@...r.kernel.org, mhiramat@...nel.org,
        bgregg@...flix.com
Subject: Re: [PATCH] perf probe: Ignore vmlinux build-id when offline
 vmlinux and dry-run used

On Tue, 24 Jan 2017 16:41:28 -0500
Josh Hunt <johunt@...mai.com> wrote:

> Commit e50243bb ("perf probe: Ignore vmlinux Build-id when offline vmlinux given")
> added the ability to ignore vmlinux when an offline vmlinux is passed and no
> l, d, or a flag is also passed. This extends that to ignore build-id when
> -n/--dry-run is used. This way we can gather probe information for offline kernels
> using the method Brendan Gregg mentions in this post:
> http://www.brendangregg.com/blog/2014-09-11/perf-kernel-line-tracing.html .

Sorry, NAK.
Could you use -D (--definition) for that usage? It directly gives you
the definition on stdout, and also ignore the buildid.

Thank you,

> 
> Ex:
>  $ ./perf probe -k ./vmlinux-3.14.59 -nv 'do_sys_open=do_sys_open:7 filename:string dfd flags op'
> 
> will generate:
>  do_sys_open+91 filename_string=+0(%si):string dfd=%di:s32 flags=%bx:s32 op=-60(%bp):u64
> 
> and then copy/paste this to the machine running the 3.14.59 kernel.
> 
> Signed-off-by: Josh Hunt <johunt@...mai.com>
> ---
>  tools/perf/builtin-probe.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
> index f87996b..e0eea723 100644
> --- a/tools/perf/builtin-probe.c
> +++ b/tools/perf/builtin-probe.c
> @@ -616,7 +616,7 @@ static int perf_del_probe_events(struct strfilter *filter)
>  	 * nor change running kernel. So if user gives offline vmlinux,
>  	 * ignore its buildid.
>  	 */
> -	if (!strchr("lda", params.command) && symbol_conf.vmlinux_name)
> +	if ((!strchr("lda", params.command) || probe_event_dry_run) && symbol_conf.vmlinux_name)
>  		symbol_conf.ignore_vmlinux_buildid = true;
>  
>  	switch (params.command) {
> -- 
> 1.9.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>