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Subject[RFC PATCH v1 01/37] libperf cpumap: improve idx function
Date
From commit 7074674e7338863e ("perf cpumap: Maintain cpumaps ordered
and without dups"), perf_cpu_map elements are sorted in ascending order.

This patch improves the perf_cpu_map__idx function by using a binary
search.

Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
---
tools/lib/perf/cpumap.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
index ca0215047c326af4..fb633272be3aaed9 100644
--- a/tools/lib/perf/cpumap.c
+++ b/tools/lib/perf/cpumap.c
@@ -265,11 +265,18 @@ bool perf_cpu_map__empty(const struct perf_cpu_map *map)

int perf_cpu_map__idx(struct perf_cpu_map *cpus, int cpu)
{
- int i;
+ int low = 0, high = cpus->nr, idx, cpu_at_idx;

- for (i = 0; i < cpus->nr; ++i) {
- if (cpus->map[i] == cpu)
- return i;
+ while (low < high) {
+ idx = (low + high) / 2;
+ cpu_at_idx = cpus->map[idx];
+
+ if (cpu_at_idx == cpu)
+ return idx;
+ else if (cpu_at_idx > cpu)
+ high = idx;
+ else
+ low = idx+1;
}

return -1;
--
2.31.1
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