[PATCH] fixup! common: introduce bthreads, co-operative barebox threads

[Ahmad Fatoum]

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 commands/bthread.c | 142 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 commands/bthread.c

diff --git a/commands/bthread.c b/commands/bthread.c
new file mode 100644
index 000000000000..1fd782f03f43
--- /dev/null
+++ b/commands/bthread.c
@@ -0,0 +1,142 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Ahmad Fatoum, Pengutronix
+ */
+
+#include <bthread.h>
+#include <errno.h>
+#include <malloc.h>
+#include <stdio.h>
+#include <command.h>
+#include <getopt.h>
+#include <clock.h>
+
+static int bthread_time(void)
+{
+	uint64_t start = get_time_ns();
+	int i = 0;
+
+	/*
+	 * How many background tasks can we have in one second?
+	 *
+	 * A low number here may point to problems with bthreads taking too
+	 * much time.
+	 */
+	while (!is_timeout(start, SECOND))
+		i++;
+
+	return i;
+}
+
+static int bthread_infinite(void *data)
+{
+	while (!bthread_should_stop())
+		;
+
+	return 0;
+}
+
+static int bthread_isolated_time(void)
+{
+	uint64_t start = get_time_ns();
+	struct bthread *bthread;
+	int i = 0;
+
+	bthread = bthread_create(bthread_infinite, NULL, "infinite");
+	if (!bthread)
+		return -ENOMEM;
+
+	bthread_wake(bthread);
+
+	/*
+	 * How many context switches can we do in one second?
+	 *
+	 * A low number here may point to problems with bthreads taking too
+	 * much time.
+	 */
+	while (!is_timeout_non_interruptible(start, SECOND)) {
+		bthread_schedule(bthread);
+		i += 2;
+	}
+
+	bthread_stop(bthread);
+	bthread_free(bthread);
+
+	return i;
+}
+
+static int bthread_printer(void *arg)
+{
+	volatile u64 start;
+	volatile int i = 0;
+	start = get_time_ns();
+
+	while (!bthread_should_stop()) {
+		if (!is_timeout_non_interruptible(start, 225 * MSECOND))
+			continue;
+
+		printf("%s yield #%d\n", __func__, ++i);
+		start = get_time_ns();
+	}
+
+	return i;
+}
+
+BAREBOX_CMD_HELP_START(bthread)
+	BAREBOX_CMD_HELP_TEXT("print info about registered barebox threads")
+	BAREBOX_CMD_HELP_TEXT("")
+	BAREBOX_CMD_HELP_TEXT("Options:")
+	BAREBOX_CMD_HELP_OPT ("-i", "Print information about registered bthreads")
+	BAREBOX_CMD_HELP_OPT ("-t", "measure how many bthreads we currently run in 1s")
+	BAREBOX_CMD_HELP_OPT ("-c", "count maximum context switches in 1s")
+	BAREBOX_CMD_HELP_OPT ("-v", "verify correct bthread operation")
+	BAREBOX_CMD_HELP_END
+
+static int do_bthread(int argc, char *argv[])
+{
+	struct bthread *bthread = NULL;
+	int ret, opt;
+	int yields;
+
+	while ((opt = getopt(argc, argv, "itcv")) > 0) {
+		switch (opt) {
+		case 'i':
+			bthread_info();
+			return 0;
+		case 'c':
+			yields = bthread_isolated_time();
+			printf("%d bthread context switches possible in 1s\n", yields);
+			break;
+		case 'v':
+			bthread = bthread_create(bthread_printer, NULL, "bthread");
+			if (!bthread)
+				return -ENOMEM;
+
+			bthread_wake(bthread);
+
+			/* fallthrough */
+		case 't':
+			yields = bthread_time();
+			printf("%d bthread yield calls in 1s\n", yields);
+		}
+
+		if (bthread) {
+			ret = bthread_stop(bthread);
+			bthread_free(bthread);
+
+			if (ret != 4 || yields < ret)
+				return COMMAND_ERROR;
+		}
+
+		return 0;
+	}
+
+	return COMMAND_ERROR_USAGE;
+}
+
+BAREBOX_CMD_START(bthread)
+	.cmd = do_bthread,
+	BAREBOX_CMD_DESC("print info about registered bthreads")
+	BAREBOX_CMD_GROUP(CMD_GRP_MISC)
+	BAREBOX_CMD_HELP(cmd_bthread_help)
+BAREBOX_CMD_END
-- 
2.29.2