From: Keith Packard <keithp@keithp.com>
Date: Mon, 21 Nov 2016 04:56:01 +0000 (-0800)
Subject: altos: Don't wait while idle if trying to minimize interrupt latency
X-Git-Tag: 1.7~102
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=992eee8e0b4c6c774f3355af107fb422019ff4e5

altos: Don't wait while idle if trying to minimize interrupt latency

Keeping the scanout running reasonably means keeping interrupt latency
constant, and that requires leaving the CPU running. Don't wait for
interrupts when the system is running in this mode.

Signed-off-by: Keith Packard <keithp@keithp.com>
---

diff --git a/src/kernel/ao_task.c b/src/kernel/ao_task.c
index e8a092aa..de23ea02 100644
--- a/src/kernel/ao_task.c
+++ b/src/kernel/ao_task.c
@@ -373,7 +373,11 @@ ao_yield(void) ao_arch_naked_define
 		if (!ao_list_is_empty(&run_queue))
 			break;
 		/* Wait for interrupts when there's nothing ready */
-		ao_arch_wait_interrupt();
+		if (ao_task_minimize_latency) {
+			ao_arch_release_interrupts();
+			ao_arch_block_interrupts();
+		} else
+			ao_arch_wait_interrupt();
 	}
 	ao_cur_task = ao_list_first_entry(&run_queue, struct ao_task, queue);
 #else