userspace/hal: reorder the main loop, no actual change

Every two months I've been wondering what this 100%-cpu main loop was, to later acknowledge it was not really 100%. This commit reorders items and makes it clear where the delay is. I tried raising it to 100ms from 25ms, but the cpu load of wrsw_hal didn't change, because most of the time we return to the main loop before the timeout, due to an RPC call being served. In my opinion we should add a check in the main loop, to call port_update_all only 10 times per second, to actually lower the CPU load of this process. Signed-off-by: Alessandro Rubini <rubini@gnudd.com>

userspace/hal: reorder the main loop, no actual change
Every two months I've been wondering what this 100%-cpu main loop was, to later acknowledge it was not really 100%. This commit reorders items and makes it clear where the delay is. I tried raising it to 100ms from 25ms, but the cpu load of wrsw_hal didn't change, because most of the time we return to the main loop before the timeout, due to an RPC call being served. In my opinion we should add a check in the main loop, to call port_update_all only 10 times per second, to actually lower the CPU load of this process. Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
5dfaba0c · Alessandro Rubini · 5628e3cc · 5dfaba0c · 5dfaba0c · 5dfaba0c
Commit 5dfaba0c authored Jan 06, 2015 by Alessandro Rubini
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Showing with 16 additions and 16 deletions

hal_exports.c userspace/wrsw_hal/hal_exports.c +2 -2

hal_main.c userspace/wrsw_hal/hal_main.c +13 -13

wrsw_hal.h userspace/wrsw_hal/wrsw_hal.h +1 -1

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--- a/userspace/wrsw_hal/hal_exports.c
+++ b/userspace/wrsw_hal/hal_exports.c
@@ -242,9 +242,9 @@ int hal_init_wripc(struct hal_port_state *hal_ports)
 }

 /* wripc update function, must be called in the main program loop */
-int hal_update_wripc()
+int hal_update_wripc(int ms_timeout)
 {
-	minipc_server_action(hal_ch, 25 /* ms */ );
+	minipc_server_action(hal_ch, ms_timeout);
 	return 0;
 }


--- a/userspace/wrsw_hal/hal_main.c
+++ b/userspace/wrsw_hal/hal_main.c
@@ -109,16 +109,6 @@ static int hal_init()
 	return 0;
 }

-/* Main loop update - polls for WRIPC requests and rolls the port
- * state machines */
-static void hal_update()
-{
-	hal_update_wripc();
-	hal_port_update_all();
-	shw_update_fans();
-//      usleep(1000);
-}
-
 /* Turns a nice and well-behaving HAL into an evil servant of satan. */
 static void hal_deamonize()
 {
@@ -191,7 +181,6 @@ static void hal_parse_cmdline(int argc, char *argv[])

 int main(int argc, char *argv[])
 {
-
 	trace_log_file("/dev/kmsg");
 	/* Prevent from running HAL twice - it will likely freeze the system */
 	if (hal_check_running()) {
@@ -205,8 +194,19 @@ int main(int argc, char *argv[])
 	if (hal_init())
 		exit(1);

-	for (;;)
-		hal_update();
+	/*
+	 * Main loop update - polls for WRIPC requests and rolls the port
+	 * state machines. This is not a busy loop, as wripc waits for
+	 * the "max ms delay". Unless an RPC call comes, and then the
+	 * delay is smaller; so this loop really consumes a lot of
+	 * cpu time.
+	 */
+	for (;;) {
+		hal_update_wripc(25 /* max ms delay */);
+		hal_port_update_all();
+		shw_update_fans();
+	}
+
 	hal_shutdown();

 	return 0;

--- a/userspace/wrsw_hal/wrsw_hal.h
+++ b/userspace/wrsw_hal/wrsw_hal.h
@@ -29,7 +29,7 @@ int hal_port_query_ports(struct hexp_port_list *list,


 int hal_init_wripc();
-int hal_update_wripc();
+int hal_update_wripc(int ms_timeout);

 int hal_add_cleanup_callback(hal_cleanup_callback_t cb);