linux-kernel - Re: [PATCH 2/2] perf, tools: Don't force MetricExprs to lower case

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Date:   Mon, 9 Oct 2017 07:07:29 -0700
From:   Andi Kleen <andi@...stfloor.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Andi Kleen <andi@...stfloor.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Wang Nan <wangnan0@...wei.com>,
        linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
        He Kuang <hekuang@...wei.com>, Alexei Starovoitov <ast@...com>
Subject: Re: [PATCH 2/2] perf, tools: Don't force MetricExprs to lower case

On Mon, Oct 09, 2017 at 03:41:51PM +0200, Jiri Olsa wrote:
> On Wed, Oct 04, 2017 at 09:27:11AM -0700, Andi Kleen wrote:
> > On Wed, Oct 04, 2017 at 12:30:52PM +0200, Jiri Olsa wrote:
> > > On Tue, Oct 03, 2017 at 01:06:05PM -0300, Arnaldo Carvalho de Melo wrote:
> > > > Em Tue, Sep 12, 2017 at 12:56:43PM -0700, Andi Kleen escreveu:
> > > > > From: Andi Kleen <ak@...ux.intel.com>
> > > > > 
> > > > > There are still problems with BPF misinterpreting some events
> > > > > that include .c. An earlier fix made it work for stand alone
> > > > > aliases, but it still fails for more complex constructs.
> > > > 
> > > > Hi Wang, Jiri,
> > > > 
> > > > 	Can you please take a look at this and see if there is something
> > > > we can do to help Andi?
> > > > 
> > > > - Arnaldo
> > > >  
> > > > > REJECT keeps trying and trying a shorter string until
> > > > > .c is matched and it appears like a valid BPF path.
> > > > > 
> > > > > % perf stat -e cpu/uops_executed.core,cmask=1/ true
> > > > > bpf: builtin compilation failed: -95, try external compiler
> > > > > ERROR: problems with path cpu/uops_executed.c: No such file or directory
> > > > > event syntax error: 'cpu/uops_executed.core,cmask=1/'
> > > > >                      \___ Failed to load cpu/uops_executed.c from source: Error when compiling BPF scriptlet
> > > > > 
> > > > > I tried to fix it, but it exceeds my flex knowledge, because
> > > > > REJECT does not interact well with BEGIN states.
> > > > > 
> > > > > The BPF syntax in its current form really causes an ambigious
> > > > > grammar.
> > > 
> > > right, it looks like we allow whole path (including / char)
> > > for BPF file, which messes up with out pmu/.../ syntax
> > > 
> > > do we need that? (Cc-ed some bpf folks)
> > > 
> > > if not attached patch seems to fix things.. otherwise
> > > we need to come up with another fix
> > 
> > I tried similar patches, but I always ran into more complex
> > situations where it still matched incorrectly.
> > 
> > e.g. try it with cpu/uops_executed.core,... vs uops_executed.core
> 
> hm, both works for me with the change:
> 
>   perf stat -e cpu/uops_executed.core/ ls
>   perf stat -e uops_executed.core ls

Ok. If it works it's fine for me.

> 
> > The only real fix would be probably to add some unique 
> > prefix for BPF, but that would break all existing users.
> 
> 
> yea, there was no response from bpf folks, but it's  probably not an optio
> 
> how about checking if the file exist like below..

I presume that would interact badly with good error messages for typos
for file names.

-Andi