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Date: Thu, 10 Aug 2017 11:13:25 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Milian Wolff <milian.wolff@...b.com>
Cc: acme@...nel.org, Jin Yao <yao.jin@...ux.intel.com>,
Linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
Arnaldo Carvalho de Melo <acme@...hat.com>,
David Ahern <dsahern@...il.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>, kernel-team@....com
Subject: Re: [PATCH v2 11/14] perf report: cache srclines for callchain nodes
Hi Milian,
On Sun, Aug 06, 2017 at 11:24:43PM +0200, Milian Wolff wrote:
> On one hand this ensures that the memory is properly freed when
> the DSO gets freed. On the other hand this significantly speeds up
> the processing of the callchain nodes when lots of srclines are
> requested. For one of my data files e.g.:
>
> Before:
>
> Performance counter stats for 'perf report -s srcline -g srcline --stdio':
>
> 52496.495043 task-clock (msec) # 0.999 CPUs utilized
> 634 context-switches # 0.012 K/sec
> 2 cpu-migrations # 0.000 K/sec
> 191,561 page-faults # 0.004 M/sec
> 165,074,498,235 cycles # 3.144 GHz
> 334,170,832,408 instructions # 2.02 insn per cycle
> 90,220,029,745 branches # 1718.591 M/sec
> 654,525,177 branch-misses # 0.73% of all branches
>
> 52.533273822 seconds time elapsedProcessed 236605 events and lost 40 chunks!
>
> After:
>
> Performance counter stats for 'perf report -s srcline -g srcline --stdio':
>
> 22606.323706 task-clock (msec) # 1.000 CPUs utilized
> 31 context-switches # 0.001 K/sec
> 0 cpu-migrations # 0.000 K/sec
> 185,471 page-faults # 0.008 M/sec
> 71,188,113,681 cycles # 3.149 GHz
> 133,204,943,083 instructions # 1.87 insn per cycle
> 34,886,384,979 branches # 1543.214 M/sec
> 278,214,495 branch-misses # 0.80% of all branches
>
> 22.609857253 seconds time elapsed
>
> Note that the difference is only this large when `--inline` is not
> passed. In such situations, we would use the inliner cache and
> thus do not run this code path that often.
>
> I think that this cache should actually be used in other places, too.
> When looking at the valgrind leak report for perf report, we see tons
> of srclines being leaked, most notably from calls to
> hist_entry__get_srcline. The problem is that get_srcline has many
> different formatting options (show_sym, show_addr, potentially even
> unwind_inlines when calling __get_srcline directly). As such, the
> srcline cannot easily be cached for all calls, or we'd have to add
> caches for all formatting combinations (6 so far). An alternative
> would be to remove the formatting options and handle that on a
> different level - i.e. print the sym/addr on demand wherever we
> actually output something. And the unwind_inlines could be moved into
> a separate function that does not return the srcline.
Agreed. Also I guess no need to unwind anymore to get a srcfile for
an entry with your change.
Thanks,
Namhyung
>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: David Ahern <dsahern@...il.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Yao Jin <yao.jin@...ux.intel.com>
> Signed-off-by: Milian Wolff <milian.wolff@...b.com>
> ---
> tools/perf/util/dso.c | 1 +
> tools/perf/util/dso.h | 1 +
> tools/perf/util/machine.c | 17 +++++++++---
> tools/perf/util/srcline.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++
> tools/perf/util/srcline.h | 7 +++++
> 5 files changed, 89 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
> index 72e6e390fd26..8c7f2862cff2 100644
> --- a/tools/perf/util/dso.c
> +++ b/tools/perf/util/dso.c
> @@ -1235,6 +1235,7 @@ void dso__delete(struct dso *dso)
> for (i = 0; i < MAP__NR_TYPES; ++i)
> symbols__delete(&dso->symbols[i]);
> inlines__tree_delete(&dso->inlined_nodes);
> + srcline__tree_delete(&dso->srclines);
>
> if (dso->short_name_allocated) {
> zfree((char **)&dso->short_name);
> diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
> index 7d1e2b3c1f10..ac3a65a30ff2 100644
> --- a/tools/perf/util/dso.h
> +++ b/tools/perf/util/dso.h
> @@ -142,6 +142,7 @@ struct dso {
> struct rb_root symbols[MAP__NR_TYPES];
> struct rb_root symbol_names[MAP__NR_TYPES];
> struct rb_root inlined_nodes;
> + struct rb_root srclines;
> struct {
> u64 addr;
> struct symbol *symbol;
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 479c42450d6a..c5ee6ba2b9ae 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -1675,11 +1675,22 @@ struct mem_info *sample__resolve_mem(struct perf_sample *sample,
>
> static char *callchain_srcline(struct map *map, struct symbol *sym, u64 ip)
> {
> + char *srcline = NULL;
> +
> if (!map || callchain_param.key == CCKEY_FUNCTION)
> - return NULL;
> + return srcline;
> +
> + srcline = srcline__tree_find(&map->dso->srclines, ip);
> + if (!srcline) {
> + bool show_sym = false;
> + bool show_addr = callchain_param.key == CCKEY_ADDRESS;
> +
> + srcline = get_srcline(map->dso, map__rip_2objdump(map, ip),
> + sym, show_sym, show_addr);
> + srcline__tree_insert(&map->dso->srclines, ip, srcline);
> + }
>
> - return get_srcline(map->dso, map__rip_2objdump(map, ip),
> - sym, false, callchain_param.key == CCKEY_ADDRESS);
> + return srcline;
> }
>
> static int add_callchain_ip(struct thread *thread,
> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
> index 01b4d5ee51fd..0c5ee741c515 100644
> --- a/tools/perf/util/srcline.c
> +++ b/tools/perf/util/srcline.c
> @@ -531,6 +531,72 @@ char *get_srcline(struct dso *dso, u64 addr, struct symbol *sym,
> return __get_srcline(dso, addr, sym, show_sym, show_addr, false);
> }
>
> +struct srcline_node {
> + u64 addr;
> + char *srcline;
> + struct rb_node rb_node;
> +};
> +
> +void srcline__tree_insert(struct rb_root *tree, u64 addr, char *srcline)
> +{
> + struct rb_node **p = &tree->rb_node;
> + struct rb_node *parent = NULL;
> + struct srcline_node *i, *node;
> +
> + node = zalloc(sizeof(struct srcline_node));
> + if (!node) {
> + perror("not enough memory for the srcline node");
> + return;
> + }
> +
> + node->addr = addr;
> + node->srcline = srcline;
> +
> + while (*p != NULL) {
> + parent = *p;
> + i = rb_entry(parent, struct srcline_node, rb_node);
> + if (addr < i->addr)
> + p = &(*p)->rb_left;
> + else
> + p = &(*p)->rb_right;
> + }
> + rb_link_node(&node->rb_node, parent, p);
> + rb_insert_color(&node->rb_node, tree);
> +}
> +
> +char *srcline__tree_find(struct rb_root *tree, u64 addr)
> +{
> + struct rb_node *n = tree->rb_node;
> +
> + while (n) {
> + struct srcline_node *i = rb_entry(n, struct srcline_node,
> + rb_node);
> +
> + if (addr < i->addr)
> + n = n->rb_left;
> + else if (addr > i->addr)
> + n = n->rb_right;
> + else
> + return i->srcline;
> + }
> +
> + return NULL;
> +}
> +
> +void srcline__tree_delete(struct rb_root *tree)
> +{
> + struct srcline_node *pos;
> + struct rb_node *next = rb_first(tree);
> +
> + while (next) {
> + pos = rb_entry(next, struct srcline_node, rb_node);
> + next = rb_next(&pos->rb_node);
> + rb_erase(&pos->rb_node, tree);
> + free_srcline(pos->srcline);
> + zfree(&pos);
> + }
> +}
> +
> struct inline_node *dso__parse_addr_inlines(struct dso *dso, u64 addr,
> struct symbol *sym)
> {
> diff --git a/tools/perf/util/srcline.h b/tools/perf/util/srcline.h
> index 0d2aca92e8c7..187a71082cb8 100644
> --- a/tools/perf/util/srcline.h
> +++ b/tools/perf/util/srcline.h
> @@ -15,6 +15,13 @@ char *__get_srcline(struct dso *dso, u64 addr, struct symbol *sym,
> bool show_sym, bool show_addr, bool unwind_inlines);
> void free_srcline(char *srcline);
>
> +// insert the srcline into the DSO, which will take ownership
> +void srcline__tree_insert(struct rb_root *tree, u64 addr, char *srcline);
> +// find previously inserted srcline
> +char *srcline__tree_find(struct rb_root *tree, u64 addr);
> +// delete all srclines within the tree
> +void srcline__tree_delete(struct rb_root *tree);
> +
> #define SRCLINE_UNKNOWN ((char *) "??:0")
>
> struct inline_list {
> --
> 2.13.3
>
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