From 6bb8f311a870d6042e0310309eb3d607ae52fe3e Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Wed, 31 Aug 2011 11:51:45 +1000 Subject: [PATCH] perf sort: Fix symbol sort output by separating unresolved samples by type I took a profile that suggested 60% of total CPU time was in the hypervisor: ... 60.20% [H] 0x33d43c 4.43% [k] ._spin_lock_irqsave 1.07% [k] ._spin_lock Using perf stat to get the user/kernel/hypervisor breakdown contradicted this. The problem is we merge all unresolved samples into the one unknown bucket. If add a comparison by sample type to sort__sym_cmp we get the real picture: ... 57.11% [.] 0x80fbf63c 4.43% [k] ._spin_lock_irqsave 1.07% [k] ._spin_lock 0.65% [H] 0x33d43c So it was almost all userspace, not hypervisor as the initial profile suggested. I found another issue while adding this. Symbol sorting sometimes shows multiple entries for the unknown bucket: ... 16.65% [.] 0x6cd3a8 7.25% [.] 0x422460 5.37% [.] yylex 4.79% [.] malloc 4.78% [.] _int_malloc 4.03% [.] _int_free 3.95% [.] hash_source_code_string 2.82% [.] 0x532908 2.64% [.] 0x36b538 0.94% [H] 0x8000000000e132a4 0.82% [H] 0x800000000000e8b0 This happens because we aren't consistent with our sorting. On one hand we check to see if both symbols match and for two unresolved samples sym is NULL so we match: if (left->ms.sym == right->ms.sym) return 0; On the other hand we use sample IP for unresolved samples when comparing against a symbol: ip_l = left->ms.sym ? left->ms.sym->start : left->ip; ip_r = right->ms.sym ? right->ms.sym->start : right->ip; This means unresolved samples end up spread across the rbtree and we can't merge them all. If we use cmp_null all unresolved samples will end up in the one bucket and the output makes more sense: ... 39.12% [.] 0x36b538 5.37% [.] yylex 4.79% [.] malloc 4.78% [.] _int_malloc 4.03% [.] _int_free 3.95% [.] hash_source_code_string 2.26% [H] 0x800000000000e8b0 Acked-by: Eric B Munson Cc: Eric B Munson Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Ian Munsie Link: http://lkml.kernel.org/r/20110831115145.4f598ab2@kryten Signed-off-by: Anton Blanchard Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/sort.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c index 401e220566fd..1ee8f1e40f18 100644 --- a/tools/perf/util/sort.c +++ b/tools/perf/util/sort.c @@ -151,11 +151,17 @@ sort__sym_cmp(struct hist_entry *left, struct hist_entry *right) { u64 ip_l, ip_r; + if (!left->ms.sym && !right->ms.sym) + return right->level - left->level; + + if (!left->ms.sym || !right->ms.sym) + return cmp_null(left->ms.sym, right->ms.sym); + if (left->ms.sym == right->ms.sym) return 0; - ip_l = left->ms.sym ? left->ms.sym->start : left->ip; - ip_r = right->ms.sym ? right->ms.sym->start : right->ip; + ip_l = left->ms.sym->start; + ip_r = right->ms.sym->start; return (int64_t)(ip_r - ip_l); } -- GitLab