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

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Date:	Wed, 17 Feb 2016 11:55:52 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
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

Em Wed, Feb 17, 2016 at 03:39:38PM +0100, Jiri Olsa escreveu:
> 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

Ok, so I'll wait for it then,

builtin-probe.c uses things like:

        set_option_flag(options, 'a', "add", PARSE_OPT_EXCLUSIVE); 
        set_option_flag(options, 'd', "del", PARSE_OPT_EXCLUSIVE);

We have:

#define OPT_BOOLEAN_FLAG(s, l, v, h, f)     { .type = OPTION_BOOLEAN,
.short_name = (s), .long_name = (l), .value = check_vtype(v, bool *),
.help = (h), .flags = (f) }


That allows setting that PARSE_OPT_EXCLUSIVE flag, but we don't have
_FLAG variants for all opt types, for instance there is no
OPT_CALLBACK_FLAG() that could be used in builtin-probe.c to avoid those
unconditional set_option_flag(EXCLUSIVE) :-\

- Arnaldo