[DTrace-devel] [PATCH 2/4] bpf: store per-CPU drop counts in the 'cpuinfo' map

[Kris Van Hees]

Drop counters for principal and aggregation buffers are tracked per-CPU
and thus need to be stored per-CPU.  The 'cpuinfo' map is a convenient
place to put those so add them in after the actual cpuinfo data for a
given CPU.

Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
 libdtrace/dt_bpf.c      | 20 ++++++++++----------
 libdtrace/dt_bpf_maps.h | 10 +++++++++-
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/libdtrace/dt_bpf.c b/libdtrace/dt_bpf.c
index f247d83d..3cf8ef89 100644
--- a/libdtrace/dt_bpf.c
+++ b/libdtrace/dt_bpf.c
@@ -604,22 +604,22 @@ gmap_create_buffers(dtrace_hdl_t *dtp)
 static int
 gmap_create_cpuinfo(dtrace_hdl_t *dtp)
 {
-	int		i, fd, rc;
-	uint32_t	key = 0;
-	dtrace_conf_t	*conf = &dtp->dt_conf;
-	size_t		ncpus = conf->max_cpuid + 1;
-	cpuinfo_t	*data;
-	cpuinfo_t	*ci;
-
-	data = dt_zalloc(dtp, ncpus * sizeof(cpuinfo_t));
+	int			i, fd, rc;
+	uint32_t		key = 0;
+	dtrace_conf_t		*conf = &dtp->dt_conf;
+	size_t			ncpus = conf->max_cpuid + 1;
+	dt_bpf_cpuinfo_t	*data;
+	cpuinfo_t		*ci;
+
+	data = dt_zalloc(dtp, ncpus * sizeof(dt_bpf_cpuinfo_t));
 	if (data == NULL)
 		return dt_set_errno(dtp, EDT_NOMEM);
 
 	for (i = 0, ci = &conf->cpus[0]; i < ncpus; i++, ci++)
-		memcpy(&data[ci->cpu_id], ci, sizeof(cpuinfo_t));
+		memcpy(&data[ci->cpu_id].ci, ci, sizeof(cpuinfo_t));
 
 	fd = create_gmap(dtp, "cpuinfo", BPF_MAP_TYPE_PERCPU_ARRAY,
-			 sizeof(uint32_t), sizeof(cpuinfo_t), 1);
+			 sizeof(uint32_t), sizeof(dt_bpf_cpuinfo_t), 1);
 	if (fd == -1)
 		return -1;
 
diff --git a/libdtrace/dt_bpf_maps.h b/libdtrace/dt_bpf_maps.h
index e33748b7..074a95db 100644
--- a/libdtrace/dt_bpf_maps.h
+++ b/libdtrace/dt_bpf_maps.h
@@ -1,6 +1,6 @@
 /*
  * Oracle Linux DTrace.
- * Copyright (c) 2019, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
  * Licensed under the Universal Permissive License v 1.0 as shown at
  * http://oss.oracle.com/licenses/upl.
  */
@@ -13,6 +13,7 @@ extern "C" {
 #endif
 
 #include <stddef.h>
+#include <dtrace/conf.h>
 
 typedef struct dt_bpf_probe	dt_bpf_probe_t;
 struct dt_bpf_probe {
@@ -29,6 +30,13 @@ struct dt_bpf_specs {
 					 * drain this buffer */
 };
 
+typedef struct dt_bpf_cpuinfo	dt_bpf_cpuinfo_t;
+struct dt_bpf_cpuinfo {
+	cpuinfo_t	ci;
+	uint64_t	buf_drops;
+	uint64_t	agg_drops;
+};
+
 #ifdef  __cplusplus
 }
 #endif
-- 
2.40.1