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Problem with CPU Load Measurements and gcc-arm-eabi optimization.
- From: lesc <lesc at zhaw dot ch>
- To: eCos Discussion <ecos-discuss at sourceware dot org>
- Date: Mon, 17 Nov 2014 14:06:41 +0100
- Subject: Problem with CPU Load Measurements and gcc-arm-eabi optimization.
- Authentication-results: sourceware.org; auth=none
Hello Everyone
I just encountered the Problem that the cyg_cpuload_create always
delivers 100% on my System. After a bit of debugging I figured out, that
the whole for-loop in idle_thread_main seems to be omitted.
I could fix this Problem with declaring
idle_thread_loops[CYGNUM_KERNEL_CPU_MAX] as volatile (patch below). But
this has maybe some consequences I am not thinking of, as the variables
are now always synced to the ram and no kept in a CPU register.
Do you see any Problem with my approach?
Regards Serafin
Patch:
From 2799f68a5e508c6bece6ec85b1e201282983b98d Mon Sep 17 00:00:00 2001
From: Serafin Leschke <lesc@zhaw.ch>
Date: Mon, 17 Nov 2014 13:51:23 +0100
Subject: [PATCH] declare idle_thread_loops as volatile
---
packages/kernel/current/src/common/thread.cxx | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/packages/kernel/current/src/common/thread.cxx
b/packages/kernel/current/src/common/thread.cxx
index 86a3dc4..bd1aa99 100644
--- a/packages/kernel/current/src/common/thread.cxx
+++ b/packages/kernel/current/src/common/thread.cxx
@@ -1211,7 +1211,7 @@ Cyg_ThreadTimer::alarm(
#endif // CYGNUM_HAL_STACK_SIZE_MINIMUM
// Loop counter for debugging/housekeeping
-cyg_uint32 idle_thread_loops[CYGNUM_KERNEL_CPU_MAX];
+volatile cyg_uint32 idle_thread_loops[CYGNUM_KERNEL_CPU_MAX];
static char
idle_thread_stack[CYGNUM_KERNEL_CPU_MAX][CYGNUM_KERNEL_THREADS_IDLE_STACK_SIZE];
--
1.9.1
--
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