Re: [PATCH 34/37] perf hists browser: Support flat callchains

From: Frederic Weisbecker
Date: Mon Nov 23 2015 - 10:16:56 EST


On Thu, Nov 19, 2015 at 02:53:20PM -0300, Arnaldo Carvalho de Melo wrote:
> From: Namhyung Kim <namhyung@xxxxxxxxxx>
>
> The flat callchain mode is to print all chains in a single, simple
> hierarchy so make it easy to see.
>
> Currently perf report --tui doesn't show flat callchains properly. With
> flat callchains, only leaf nodes are added to the final rbtree so it
> should show entries in parent nodes. To do that, add parent_val list to
> struct callchain_node and show them along with the (normal) val list.
>
> For example, consider following callchains with '-g graph'.
>
> $ perf report -g graph
> - 39.93% swapper [kernel.vmlinux] [k] intel_idle
> intel_idle
> cpuidle_enter_state
> cpuidle_enter
> call_cpuidle
> - cpu_startup_entry
> 28.63% start_secondary
> - 11.30% rest_init
> start_kernel
> x86_64_start_reservations
> x86_64_start_kernel
>
> Before:
> $ perf report -g flat
> - 39.93% swapper [kernel.vmlinux] [k] intel_idle
> 28.63% start_secondary
> - 11.30% rest_init
> start_kernel
> x86_64_start_reservations
> x86_64_start_kernel
>
> After:
> $ perf report -g flat
> - 39.93% swapper [kernel.vmlinux] [k] intel_idle
> - 28.63% intel_idle
> cpuidle_enter_state
> cpuidle_enter
> call_cpuidle
> cpu_startup_entry
> start_secondary
> - 11.30% intel_idle
> cpuidle_enter_state
> cpuidle_enter
> call_cpuidle
> cpu_startup_entry
> start_kernel
> x86_64_start_reservations
> x86_64_start_kernel
>
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Tested-by: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
> Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
> Cc: David Ahern <dsahern@xxxxxxxxx>
> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Kan Liang <kan.liang@xxxxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Link: http://lkml.kernel.org/r/1447047946-1691-8-git-send-email-namhyung@xxxxxxxxxx
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> ---

[...]

> +int callchain_node__make_parent_list(struct callchain_node *node)
> +{
> + struct callchain_node *parent = node->parent;
> + struct callchain_list *chain, *new;
> + LIST_HEAD(head);
> +
> + while (parent) {
> + list_for_each_entry_reverse(chain, &parent->val, list) {
> + new = malloc(sizeof(*new));
> + if (new == NULL)
> + goto out;
> + *new = *chain;
> + new->has_children = false;
> + list_add_tail(&new->list, &head);
> + }
> + parent = parent->parent;
> + }
> +
> + list_for_each_entry_safe_reverse(chain, new, &head, list)
> + list_move_tail(&chain->list, &node->parent_val);
> +
> + if (!list_empty(&node->parent_val)) {
> + chain = list_first_entry(&node->parent_val, struct callchain_list, list);
> + chain->has_children = rb_prev(&node->rb_node) || rb_next(&node->rb_node);
> +
> + chain = list_first_entry(&node->val, struct callchain_list, list);
> + chain->has_children = false;

I'm a bit puzzled with this, can't we rewind through the parents on printing or adding
to the flat rbtree instead of having this parent_val field?

Thanks.
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