linux-kernel - Re: [PATCH 20/57] perf c2c report: Add dcacheline dimension key

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Date:   Wed, 5 Oct 2016 16:02:49 +0200
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>,
        Don Zickus <dzickus@...hat.com>, Joe Mario <jmario@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH 20/57] perf c2c report: Add dcacheline dimension key

On Wed, Oct 05, 2016 at 10:26:58AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Wed, Oct 05, 2016 at 03:09:29PM +0200, Jiri Olsa escreveu:
> > On Wed, Oct 05, 2016 at 02:45:37PM +0200, Jiri Olsa wrote:
> > 
> > SNIP
> > 
> > > > > +
> > > > > +	if (he->mem_info)
> > > > > +		addr = cl_address(he->mem_info->daddr.addr);
> > > > > +
> > > > > +	return snprintf(hpp->buf, hpp->size, "%*s", width, hex_str(addr));
> > > > 
> > > > So here you get that static buffer and then truncate it? Wouldn't the
> > > > perf_hpp stuff take care of this? Can't we stop using that static buffer
> > > > and this truncation at such a level?
> > > 
> > > I think we need to cut it on this level, but I actualy might recall some
> > > change you did for perf_hpp to cut this on column width later on?
> > > 
> > > I'll check on that..
> > 
> > ok, so it's cut later on, but it allows only for left-side alignment
> > while we use the right-side one
> > 
> > if I leave it on perf_hpp to deal with it I end up with following output:
> > (check the Cacheline column)
> 
> Which is not _that_ bad, I guess it gets like that because we expect
> kernel addresses as well (longer)? 
> 
> [root@...et ~]# grep icmp_rcv /proc/kallsyms  | cut -d' ' -f 1 | wc -c
> 17
> [root@...et ~]# echo -n .................. | wc -c
> 18
> [root@...et ~]# 
> 
> How to indicate to the hpp code that we want right alignment? Namhyung?

hum, the hist_entry__snprintf_alignment just adds missing spaces
if there's any..

I think we should allow the upper layer to align based on its needs

but maybe change hist_entry__snprintf_alignment to also force the
width (like cut the overlap) in case it overflows

jirka