Add new tool for observing metaslab allocations

bpf/estat/metaslab-alloc.c

@@ -0,0 +1,141 @@
+/*
+ * Copyright 2020 Delphix. All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include <sys/metaslab.h>
+#include <sys/metaslab_impl.h>
+#include <sys/vdev_impl.h>
+#include <sys/spa_impl.h>
+
+#define VD_NAME_SIZE 32
+typedef struct {
+	u64 ts;
+	u64 size;
+	u64 asize;
+	u64 alloc_time;
+	char vd_name[VD_NAME_SIZE];
+} data_t;
+
+BPF_HASH(data_map, u32, data_t);
+
+#ifndef OPTARG
+#define	POOL "domain0"
+#else
+#define	POOL (OPTARG)
+#endif
+
+static inline bool
+equal_to_pool(char *str)
+{
+	char comparand[sizeof (POOL)];
+	bpf_probe_read(&comparand, sizeof (comparand), str);
+	char compare[] = POOL;
+
+	for (int i = 0; i < sizeof (comparand); ++i)
+		if (compare[i] != comparand[i])
+			return (false);
+
+	return (true);
+}
+
+// @@ kprobe|metaslab_alloc_dva|metaslab_alloc_dva_entry
+int
+metaslab_alloc_dva_entry(struct pt_regs *ctx,
+    spa_t *spa, metaslab_class_t *mc, uint64_t psize)
+{
+	u32 tid = bpf_get_current_pid_tgid();
+	data_t data = {};
+
+	if (!equal_to_pool(spa->spa_name))
+		return (0);
+
+	data.ts = bpf_ktime_get_ns();
+	data.size = psize;
+
+	data_map.update(&tid, &data);
+
+	return (0);
+}
+
+// @@ kprobe|metaslab_group_alloc|metaslab_group_alloc_entry
+int
+metaslab_group_alloc_entry(struct pt_regs *ctx,
+    metaslab_group_t *mg, zio_alloc_list_t *zal, uint64_t asize)
+{
+	u32 tid = bpf_get_current_pid_tgid();
+	data_t *data = data_map.lookup(&tid);
+
+	if (data == NULL || data->ts == 0)
+		return (0);
+
+	data->asize = asize;
+	data->alloc_time = bpf_ktime_get_ns();
+
+	if (mg->mg_vd->vdev_path != NULL) {
+		bpf_probe_read_str(data->vd_name,
+		    sizeof(data->vd_name), mg->mg_vd->vdev_path);
+	} else {
+		bpf_probe_read_str(data->vd_name,
+		    sizeof(data->vd_name), mg->mg_vd->vdev_ops->vdev_op_type);
+	}
+
+	return (0);
+}
+
+// @@ kretprobe|metaslab_group_alloc|metaslab_group_alloc_exit
+int
+metaslab_group_alloc_exit(struct pt_regs *ctx)
+{
+	u32 tid = bpf_get_current_pid_tgid();
+	data_t *data = data_map.lookup(&tid);
+	char failure[] = "failure";
+	char success[] = "success";
+	char *axis;
+
+	if (data == NULL || data->ts == 0)
+		return (0);
+
+	if (PT_REGS_RC(ctx) == -1ULL) {
+		axis = failure;
+	} else {
+		axis = success;
+	}
+
+	AGGREGATE_DATA(data->vd_name, axis,
+		bpf_ktime_get_ns() - data->ts, data->asize);
+
+	data->asize = 0;
+	data->alloc_time = 0;
+	data->vd_name[0] = '\0';
+
+	return (0);
+}
+
+// @@ kretprobe|metaslab_alloc_dva|metaslab_alloc_dva_exit
+int
+metaslab_alloc_dva_exit(struct pt_regs *ctx,
+    spa_t *spa, metaslab_class_t *mc, uint64_t psize)
+{
+	u32 tid = bpf_get_current_pid_tgid();
+	data_t *data = data_map.lookup(&tid);
+
+	if (data == NULL || data->ts == 0)
+		return (0);
+
+	if (PT_REGS_RC(ctx) == 0)
+		return (0);
+
+	char name[] = "allocation failures";
+	char axis = 0;
+	AGGREGATE_DATA(name, &axis,
+		bpf_ktime_get_ns() - data->ts, data->size);
+
+	data->ts = 0;
+	data->size = 0;
+
+	data_map.delete(&tid);
+
+	return (0);
+}