@@ -601,6 +601,17 @@ config CYCLIC_MAX_CPU_TIME_US
takes longer than this duration this function will get unregistered
automatically.
+config CYCLIC_RATELIMIT_US
+ int "Sets the min time/delay in us after a new call into schedule is done"
+ default 100
+ help
+ The min allowed time after with a new call into the cyclic
+ infrastructure is allowed. This results in a rate limiting of the
+ all functions hooked into the cyclic interface.
+ As it's been noticed that on some platforms, that high frequent
+ calls to schedule() (replaced from WATCHDOG_RESET) may lead to a
+ performance degradation.
+
endif # CYCLIC
config EVENT
@@ -12,6 +12,7 @@
#include <log.h>
#include <malloc.h>
#include <time.h>
+#include <linux/bug.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <asm/global_data.h>
@@ -109,8 +110,30 @@ void schedule(void)
* schedule() might get called very early before the cyclic IF is
* ready. Make sure to only call cyclic_run() when it's initalized.
*/
- if (gd)
- cyclic_run();
+ if (gd) {
+ uint64_t now;
+
+ /*
+ * Add some rate limiting to not call into the cyclic IF too
+ * ofter. As it's been noticed that on some platforms, that
+ * high frequent calls to schedule() (replaced from
+ * WATCHDOG_RESET) may lead to a performance degradation.
+ * -> Do not reset the watchdog too often
+ */
+ now = timer_get_us();
+ if (time_after_eq64(now, gd->cyclic_next_call)) {
+ cyclic_run();
+ gd->cyclic_next_call = now + CONFIG_CYCLIC_RATELIMIT_US;
+ } else {
+ /*
+ * Throw a warning (only once) to help identifying
+ * frantic callers
+ */
+ WARN_ONCE(1, "schedule() called very often, now = %lld us next call at %lld us, dt = %lld us\n",
+ now, gd->cyclic_next_call,
+ gd->cyclic_next_call - now);
+ }
+ }
}
int cyclic_unregister_all(void)
@@ -490,6 +490,7 @@ struct global_data {
* @cyclic_list: list of registered cyclic functions
*/
struct hlist_head cyclic_list;
+ uint64_t cyclic_next_call;
#endif
/**
* @dmtag_list: List of DM tags
This patch adds the new Kconfig option CONFIG_CYCLIC_RATELIMIT_US which defines the min allowed time after with a new call into the cyclic infrastructure is allowed. This results in a rate limiting of the all functions hooked into the cyclic interface. As it's been noticed that on some platforms, that high frequent calls to schedule() (replaced from WATCHDOG_RESET) may lead to a performance degradation. When a high frequent calling into schedule() is detected, a warning is logged only once to help indentify this frantic caller. Signed-off-by: Stefan Roese <sr@denx.de> Cc: Simon Glass <sjg@chromium.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> --- - Some spelling fixes (Simon) - Minor coding style improvement in comment (Simon) common/Kconfig | 11 +++++++++++ common/cyclic.c | 27 +++++++++++++++++++++++++-- include/asm-generic/global_data.h | 1 + 3 files changed, 37 insertions(+), 2 deletions(-)