From: Ahmad Fatoum <[email protected]> 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 <[email protected]> --- 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 [email protected] http://lists.infradead.org/mailman/listinfo/barebox
