From: Frederic Weisbecker <[email protected]> When a new callchain child branch matches an existing one in the rbtree, the comparison of its first entry is performed twice:
1) From append_chain_children() on branch lookup 2) If 1) reports a match, append_chain() then compares all entries of the new branch against the matching node in the rbtree, and this comparison includes the first entry of the new branch again. Lets shortcut this by performing the whole comparison only from append_chain() which then returns the result of the comparison between the first entry of the new branch and the iterating node in the rbtree. If the first entry matches, the lookup on the current level of siblings stops and propagates to the children of the matching nodes. This results in less comparisons performed by the CPU. Signed-off-by: Frederic Weisbecker <[email protected]> Acked-by: Namhyung Kim <[email protected]> Cc: Adrian Hunter <[email protected]> Cc: David Ahern <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]> --- tools/perf/util/callchain.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c index 9eb4f57f8663..662867d5c374 100644 --- a/tools/perf/util/callchain.c +++ b/tools/perf/util/callchain.c @@ -15,6 +15,8 @@ #include <errno.h> #include <math.h> +#include "asm/bug.h" + #include "hist.h" #include "util.h" #include "sort.h" @@ -358,19 +360,14 @@ append_chain_children(struct callchain_node *root, /* lookup in childrens */ while (*p) { s64 ret; - struct callchain_list *cnode; parent = *p; rnode = rb_entry(parent, struct callchain_node, rb_node_in); - cnode = list_first_entry(&rnode->val, struct callchain_list, - list); - /* just check first entry */ - ret = match_chain(node, cnode); - if (ret == 0) { - append_chain(rnode, cursor, period); + /* If at least first entry matches, rely to children */ + ret = append_chain(rnode, cursor, period); + if (ret == 0) goto inc_children_hit; - } if (ret < 0) p = &parent->rb_left; @@ -396,6 +393,7 @@ append_chain(struct callchain_node *root, u64 start = cursor->pos; bool found = false; u64 matches; + int cmp = 0; /* * Lookup in the current node @@ -410,7 +408,8 @@ append_chain(struct callchain_node *root, if (!node) break; - if (match_chain(node, cnode) != 0) + cmp = match_chain(node, cnode); + if (cmp) break; found = true; @@ -420,9 +419,10 @@ append_chain(struct callchain_node *root, /* matches not, relay no the parent */ if (!found) { + WARN_ONCE(!cmp, "Chain comparison error\n"); cursor->curr = curr_snap; cursor->pos = start; - return -1; + return cmp; } matches = cursor->pos - start; -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
