From e4053b0d093ac2570197d5cef454a33e58b9c817 Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Mon, 31 Mar 2025 14:36:26 +0200
Subject: [PATCH] MINOR: cpu-topo: add a dump of thread-to-CPU mapping to -dc

When emitting the CPU topology info with -dc, also emit a list of
thread-to-CPU mapping. The group/thread and thread ID are emitted
with the list of their CPUs on each line. The count of CPUs is shown
to ease comparisons, and as much as possible, we try to pack identical
lines within a group by showing thread ranges.
---
 src/cpu_topo.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/src/cpu_topo.c b/src/cpu_topo.c
index 009a11a3f..8d9b0a7b8 100644
--- a/src/cpu_topo.c
+++ b/src/cpu_topo.c
@@ -214,6 +214,7 @@ void cpu_dump_topology(const struct ha_cpu_topo *topo)
 {
 	int has_smt = 0;
 	int cpu, lvl;
+	int grp, thr;
 
 	for (cpu = 0; cpu <= cpu_topo_lastcpu; cpu++)
 		if (ha_cpu_topo[cpu].th_cnt > 1)
@@ -263,6 +264,67 @@ void cpu_dump_topology(const struct ha_cpu_topo *topo)
 		       ha_cpu_clusters[cpu].nb_cores,
 		       ha_cpu_clusters[cpu].capa);
 	}
+
+	printf("Thread CPU Bindings:\n  Tgrp/Thr  Tid        CPU set\n");
+	for (grp = 0; grp < global.nbtgroups; grp++) {
+		int first, last;
+		int min, max;
+
+		first = ha_tgroup_info[grp].base;
+		last  = ha_tgroup_info[grp].base + ha_tgroup_info[grp].count - 1;
+
+		min = max = -1;
+		for (thr = first; thr <= last; thr++) {
+			if (min < 0)
+				min = thr;
+
+			if (thr == last ||
+			    !ha_cpuset_isequal(&cpu_map[grp].thread[min - first],
+					       &cpu_map[grp].thread[thr + 1 - first]))
+				max = thr;
+
+			if (min >= 0 && max >= 0) {
+				/* we have a range */
+				char str[1024];
+				int len = 0;
+				int len2;
+
+				/* print group/thread-range */
+				len += snprintf(str + len, sizeof(str) - len, "%d/%d", grp + 1, min - first + 1);
+				if (min != max)
+					len += snprintf(str + len, sizeof(str) - len, "-%d", max - first + 1);
+
+				/* max len is 8: "64/64-64", plus 2 spaces = 10 */
+				while (len < 10) {
+					str[len++] = ' ';
+					str[len] = 0;
+				}
+
+				/* append global thread range */
+				len += snprintf(str + len, sizeof(str) - len, "%d", min + 1);
+				if (min != max)
+					len += snprintf(str + len, sizeof(str) - len, "-%d", max + 1);
+
+				/* max len is 9: "4096-4096", plus 2 spaces = 11, plus 10 initial chars = 21 */
+				while (len < 21) {
+					str[len++] = ' ';
+					str[len] = 0;
+				}
+
+				if (ha_cpuset_count(&cpu_map[grp].thread[thr - first]))
+					len += snprintf(str + len, sizeof(str) - len, "%d: ", ha_cpuset_count(&cpu_map[grp].thread[thr - first]));
+
+				len2 = print_cpu_set(str + len, sizeof(str) - len, &cpu_map[grp].thread[thr - first]);
+				if (len2 > sizeof(str) - len)
+					snprintf(str + len, sizeof(str) - len, "<too_large>");
+				else if (len2 == 0)
+					snprintf(str + len, sizeof(str) - len, "<all>");
+
+				printf("  %s\n", str);
+				min = max = -1;
+			}
+		}
+	}
 }
 
 /* function used by qsort to re-arrange CPUs by index only, to restore original