From: Ahmad Fatoum <ahmad@xxxxxx>
This command is meant to show how to use the bthread API as well as
help with debugging. It's a bit overcomplicated to exercise aspects
of the API, like scheduling from both secondary and primary thread.
Signed-off-by: Ahmad Fatoum <ahmad@xxxxxx>
---
commands/Kconfig | 9 +++
commands/Makefile | 1 +
commands/bthread.c | 195 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 205 insertions(+)
create mode 100644 commands/bthread.c
diff --git a/commands/Kconfig b/commands/Kconfig
index 520ad4b1dea3..6d84c956e576 100644
--- a/commands/Kconfig
+++ b/commands/Kconfig
@@ -253,6 +253,15 @@ config CMD_POLLER
is_timeout() or one of the various delay functions. The poller command prints
informations about registered pollers.
+config CMD_BTHREAD
+ tristate
+ prompt "bthread"
+ depends on BTHREAD
+ help
+ barebox threads are cooperatively-scheduled (green) threads that are running in
+ the background whenever code executes is_timeout() or one of the various delay
+ functions. The bthread command prints informations about registered bthreads.
+
config CMD_SLICE
tristate
prompt "slice"
diff --git a/commands/Makefile b/commands/Makefile
index 034c0e6383d3..cdf14a5e1d8d 100644
--- a/commands/Makefile
+++ b/commands/Makefile
@@ -129,6 +129,7 @@ obj-$(CONFIG_CMD_MMC_EXTCSD) += mmc_extcsd.o
obj-$(CONFIG_CMD_NAND_BITFLIP) += nand-bitflip.o
obj-$(CONFIG_CMD_SEED) += seed.o
obj-$(CONFIG_CMD_IP_ROUTE_GET) += ip-route-get.o
+obj-$(CONFIG_CMD_BTHREAD) += bthread.o
obj-$(CONFIG_CMD_UBSAN) += ubsan.o
UBSAN_SANITIZE_ubsan.o := y
diff --git a/commands/bthread.c b/commands/bthread.c
new file mode 100644
index 000000000000..05dfa68cc597
--- /dev/null
+++ b/commands/bthread.c
@@ -0,0 +1,195 @@
+/* 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_run(bthread_infinite, NULL, "infinite");
+ if (!bthread)
+ return -ENOMEM;
+
+ /* main thread is the first in the run queue. Newly created bthread
+ * is the last. So if main_thread explicitly schedules new bthread,
+ * it will schedule back to main_thread afterwards and we won't
+ * execute any other threads in-between.
+ */
+
+ 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;
+
+ if ((long)arg == i++)
+ printf("%s yield #%d\n", bthread_name(current), i);
+ start = get_time_ns();
+ }
+
+ return i;
+}
+
+static int yields;
+
+static int bthread_spawner(void *arg)
+{
+ struct bthread *bthread[4];
+ volatile u64 start;
+ volatile int i = 0;
+ int ret = 0;
+ int ecode;
+
+ start = get_time_ns();
+
+ for (i = 0; i < ARRAY_SIZE(bthread); i++) {
+ bthread[i] = bthread_run(bthread_printer, (void *)i,
+ "%s-bthread%u", bthread_name(current), i+1);
+ if (!bthread[i]) {
+ ret = -ENOMEM;
+ goto cleanup;
+ }
+ }
+
+ while (!bthread_should_stop())
+ ;
+
+cleanup:
+ while (i--) {
+ ecode = bthread_stop(bthread[i]);
+ bthread_free(bthread[i]);
+
+ if (!ret && (ecode != 4 || yields < ecode))
+ ret = -EIO;
+ }
+
+ return ret;
+}
+
+struct spawn {
+ struct bthread *bthread;
+ struct list_head list;
+};
+
+static int do_bthread(int argc, char *argv[])
+{
+ LIST_HEAD(spawners);
+ struct spawn *spawner, *tmp;
+ int ret = 0;
+ int ecode, opt, i = 0;
+ bool time = false;
+
+ while ((opt = getopt(argc, argv, "itcv")) > 0) {
+ switch (opt) {
+ case 'i':
+ bthread_info();
+ break;
+ case 'c':
+ yields = bthread_isolated_time();
+ printf("%d bthread context switches possible in 1s\n", yields);
+ break;
+ case 'v':
+ spawner = xzalloc(sizeof(*spawner));
+ spawner->bthread = bthread_run(bthread_spawner, NULL,
+ "spawner%u", ++i);
+ if (!spawner->bthread) {
+ free(spawner);
+ ret = -ENOMEM;
+ goto cleanup;
+ }
+
+ /* We create intermediate spawning threads to test thread
+ * creation and scheduling from non-main thread.
+ */
+ list_add(&spawner->list, &spawners);
+
+ /* fallthrough */
+ case 't':
+ time = true;
+ }
+ }
+
+ if (time) {
+ yields = bthread_time();
+ printf("%d bthread yield calls in 1s\n", yields);
+ }
+
+cleanup:
+ list_for_each_entry_safe(spawner, tmp, &spawners, list) {
+ ecode = bthread_stop(spawner->bthread);
+ bthread_free(spawner->bthread);
+ if (!ret && ecode)
+ ret = ecode;
+ free(spawner);
+ }
+
+ return ret;
+}
+
+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
+
+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
_______________________________________________
barebox mailing list
barebox@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/barebox
