From de87074da6c0a42b9b2170863b91e4845354da9c Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Wed, 16 Jul 2025 19:54:20 -0400
Subject: kernel: Add initial accounting logic

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/include/sys/sched.h | 14 ++++++++
 sys/kern/kern_accnt.c   | 94 +++++++++++++++++++++++++++++++++++++++++++++++++
 sys/kern/kern_sched.c   |  3 ++
 3 files changed, 111 insertions(+)
 create mode 100644 sys/kern/kern_accnt.c

diff --git a/sys/include/sys/sched.h b/sys/include/sys/sched.h
index 7d17607..f4d99f9 100644
--- a/sys/include/sys/sched.h
+++ b/sys/include/sys/sched.h
@@ -33,8 +33,22 @@
 #include <sys/proc.h>
 #include <sys/cdefs.h>
 
+/*
+ * Scheduler statistics
+ *
+ * @nproc: Number processes running
+ * @ncpu: Number of CPU cores
+ * @quantum_usec: Scheduler quantum (microseconds)
+ */
+struct sched_stat {
+    size_t nproc;
+    uint16_t ncpu;
+    uint32_t quantum_usec;
+};
+
 #if defined(_KERNEL)
 
+void sched_stat(struct sched_stat *statp);
 void sched_init(void);
 void sched_yield(void);
 
diff --git a/sys/kern/kern_accnt.c b/sys/kern/kern_accnt.c
new file mode 100644
index 0000000..5ef8150
--- /dev/null
+++ b/sys/kern/kern_accnt.c
@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * System Accounting
+ */
+
+#include <sys/sched.h>
+#include <sys/schedvar.h>
+#include <sys/proc.h>
+#include <fs/ctlfs.h>
+#include <machine/cpu.h>
+#include <string.h>
+
+/* Called within kern_sched.c */
+void sched_accnt_init(void);
+
+static struct ctlops sched_stat_ctl;
+extern volatile size_t g_nthreads;
+
+static int
+ctl_stat_read(struct ctlfs_dev *cdp, struct sio_txn *sio)
+{
+    struct sched_stat stat;
+
+    if (sio->len > sizeof(stat)) {
+        sio->len = sizeof(stat);
+    }
+
+    sched_stat(&stat);
+    memcpy(sio->buf, &stat, sio->len);
+    return sio->len;
+}
+
+/*
+ * Get scheduler accounting information
+ *
+ * @statp: Info gets copied here
+ */
+void
+sched_stat(struct sched_stat *statp)
+{
+    statp->nproc = atomic_load_64(&g_nthreads);
+    statp->ncpu = cpu_count();
+    statp->quantum_usec = DEFAULT_TIMESLICE_USEC;
+}
+
+void
+sched_accnt_init(void)
+{
+    char devname[] = "sched";
+    struct ctlfs_dev ctl;
+
+    /*
+     * Register some accounting information in
+     * '/ctl/sched/stat'
+     */
+    ctl.mode = 0444;
+    ctlfs_create_node(devname, &ctl);
+    ctl.devname = devname;
+    ctl.ops = &sched_stat_ctl;
+    ctlfs_create_entry("stat", &ctl);
+}
+
+static struct ctlops sched_stat_ctl = {
+    .read = ctl_stat_read,
+    .write = NULL
+};
diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c
index 24806db..02d19df 100644
--- a/sys/kern/kern_sched.c
+++ b/sys/kern/kern_sched.c
@@ -46,6 +46,7 @@
 #define pr_trace(fmt, ...) kprintf("ksched: " fmt, ##__VA_ARGS__)
 
 void sched_switch(struct trapframe *tf);
+void sched_accnt_init(void);
 
 static sched_policy_t policy = SCHED_POLICY_MLFQ;
 
@@ -306,4 +307,6 @@ sched_init(void)
 
     pr_trace("prepared %d queues (policy=0x%x)\n",
         SCHED_NQUEUE, policy);
+
+    sched_accnt_init();
 }
-- 
cgit v1.2.3