linux-kernel - Re: [PATCH 01/23] perf record: Add --all-user/--all-kernel options

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Message-ID: <20160217143938.GA23265@krava.brq.redhat.com>
Date:	Wed, 17 Feb 2016 15:39:38 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Jiri Olsa <jolsa@...nel.org>, lkml <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Stephane Eranian <eranian@...gle.com>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 01/23] perf record: Add --all-user/--all-kernel options

On Tue, Feb 16, 2016 at 01:56:01PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Feb 15, 2016 at 09:34:31AM +0100, Jiri Olsa escreveu:
> > Allow user to easily switch all events to user or
> > kernel space with simple --all-user or --all-kernel
> > options.
> > 
> > This will be handy within perf mem/c2c wrappers to
> > switch easily monitoring modes.
> 
> Humm, some oddities:
> 
>   # perf record --all-user -e cycles -a
>   # perf report --tui       # And then notice there are some kernel samples, zoom into kernel DSO
>   Samples: 7  of event 'cycles', Event count (approx.): 3158810, DSO: [kernel.vmlinux]
>   Overhead  Comman  Symbol
>     84.05%  chrome  [k] page_fault
>     15.73%  chrome  [k] entry_SYSCALL_64
>      0.22%  chrome  [k] apic_timer_interrupt
> 
> Ditto when using --all-kernel, some userspace samples are there, also perhaps we
> should show "cycles:u" or "cycles:k" when this --all-user or --all-kernel features
> are used.
> 
> Need to investigate why there are kernel samples when --all-user is used and
> the other way around as well.
> 
> Also if I use both it quietly accepts and shows just one of them, I guess we
> should bail out in case someone tries both.

right, that should be handled with warning and exit
I'll do it in next version

thanks,
jirka