Re: [PATCH v4 12/15] perf report: cache failed lookups of inlined frames

Milian Wolff
2017-10-08T20:28:30Z

On Donnerstag, 5. Oktober 2017 05:43:38 CEST Namhyung Kim wrote:
> On Sun, Oct 01, 2017 at 04:30:57PM +0200, Milian Wolff wrote:
> > When no inlined frames could be found for a given address,
> > we did not store this information anywhere. That means we
> > potentially do the costly inliner lookup repeatedly for
> > cases where we know it can never succeed.
> >
> > This patch makes dso__parse_addr_inlines always return a
> > valid inline_node. It will be empty when no inliners are
> > found. This enables us to cache the empty list in the DSO,
> > thereby improving the performance when many addresses
> > fail to find the inliners.
> >
> > For my trivial example, the performance impact is already
> > quite significant:
> >
> > Before:
> >
> > ~~~~~
> >
> > Performance counter stats for 'perf report --stdio --inline -g srcline -s
srcline' (5 runs):
> > 594.804032 task-clock (msec) # 0.998 CPUs utilized
> > ( +- 0.07% )>
> > 53 context-switches # 0.089 K/sec
> > ( +- 4.09% )>
> > 0 cpu-migrations # 0.000 K/sec
> > ( +-100.00% )>
> > 5,687 page-faults # 0.010 M/sec
> > ( +- 0.02% )>
> > 2,300,918,213 cycles # 3.868 GHz
> > ( +- 0.09% ) 4,395,839,080 instructions
> > # 1.91 insn per cycle ( +- 0.00% )>
> > 939,177,205 branches # 1578.969 M/sec
> > ( +- 0.00% )>
> > 11,824,633 branch-misses # 1.26% of all
> > branches ( +- 0.10% )>
> > 0.596246531 seconds time elapsed
> > ( +- 0.07% )>
> > ~~~~~
> >
> > After:
> >
> > ~~~~~
> >
> > Performance counter stats for 'perf report --stdio --inline -g srcline -s
srcline' (5 runs):
> > 113.111405 task-clock (msec) # 0.990 CPUs utilized
> > ( +- 0.89% )>
> > 29 context-switches # 0.255 K/sec
> > ( +- 54.25% )>
> > 0 cpu-migrations # 0.000 K/sec
> >
> > 5,380 page-faults # 0.048 M/sec
> > ( +- 0.01% )>
> > 432,378,779 cycles # 3.823 GHz
> > ( +- 0.75% ) 670,057,633 instructions
> > # 1.55 insn per cycle ( +- 0.01% ) 141,001,247
> > branches # 1246.570 M/sec (
> > +- 0.01% )>
> > 2,346,845 branch-misses # 1.66% of all
> > branches ( +- 0.19% )>
> > 0.114222393 seconds time elapsed
> > ( +- 1.19% )>
> > ~~~~~
> >
> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> > Cc: David Ahern <dsahern@gmail.com>
> > Cc: Namhyung Kim <namhyung@kernel.org>
> > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> > Cc: Yao Jin <yao.jin@linux.intel.com>
> > Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
> > ---
>
> [SNIP]
>
> > diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
> > index 69241d805275..26d9954dc19e 100644
> > --- a/tools/perf/util/srcline.c
> > +++ b/tools/perf/util/srcline.c
> > @@ -353,17 +353,8 @@ static struct inline_node *addr2inlines(const char
> > *dso_name, u64 addr,>
> > INIT_LIST_HEAD(&node->val);
> > node->addr = addr;
> >
> > - if (!addr2line(dso_name, addr, NULL, NULL, dso, TRUE, node, sym))
> > - goto out_free_inline_node;
> > -
> > - if (list_empty(&node->val))
> > - goto out_free_inline_node;
> > -
> > - return node;
> > -
> > -out_free_inline_node:
> > - inline_node__delete(node);
> > - return NULL;
> > + addr2line(dso_name, addr, NULL, NULL, dso, TRUE, node, sym);
> > + return node;
>
> Whitespace demanged.
>
> Also please use 'true' instead of 'TRUE' for consistency (I know this
> is not your fault).

Done for the next iteration of this series, thanks!

--
Milian Wolff | milian.wolff@kdab.com | Senior Software Engineer
KDAB (Deutschland) GmbH&Co KG, a KDAB Group company
Tel: +49-30-521325470
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