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mcs: allow kernel WCET estimate to be scaled

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This configuration option allows for building images destined for
simulators, which may not simulate as fast as hardware, to still be
used.
This commit is contained in:
Adrian Danis
2017-08-23 16:48:31 +10:00
committed by Kent Mcleod
parent 2329cd81dc
commit 4768465027
3 changed files with 19 additions and 2 deletions
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12
config.cmake
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@@ -442,4 +442,16 @@ config_option(
# of the currently running thread without a capability. # of the currently running thread without a capability.
config_set(KernelSetTLSBaseSelf SET_TLS_BASE_SELF ${KernelSetTLSBaseSelf}) config_set(KernelSetTLSBaseSelf SET_TLS_BASE_SELF ${KernelSetTLSBaseSelf})
config_string(
KernelWcetScale KERNEL_WCET_SCALE
"Multiplier to scale kernel WCET estimate by: the kernel WCET estimate \
is used to ensure a thread has enough budget to get in and out of the \
kernel. When running in a simulator the WCET estimate, which is tuned \
for hardware, may not be sufficient. This option provides a hacky knob \
that can be fiddled with when running inside a simulator."
DEFAULT 1
UNQUOTE
DEPENDS "KernelIsMCS" UNDEF_DISABLED
)
add_config_library(kernel "${configure_string}") add_config_library(kernel "${configure_string}")

4
include/config.h
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@@ -33,6 +33,10 @@
#ifndef CONFIG_BOOT_THREAD_TIME_SLICE #ifndef CONFIG_BOOT_THREAD_TIME_SLICE
#define CONFIG_BOOT_THREAD_TIME_SLICE 5 #define CONFIG_BOOT_THREAD_TIME_SLICE 5
#endif #endif
#ifndef CONFIG_KERNEL_WCET_SCALE
#define CONFIG_KERNEL_WCET_SCALE 1
#endif
#endif #endif
/* the number of scheduler domains */ /* the number of scheduler domains */

5
include/kernel/sporadic.h
View File

@@ -28,6 +28,7 @@
* minimum size is 2, and can be configured by the user per scheduling context * minimum size is 2, and can be configured by the user per scheduling context
* above this) the next refill is merged. * above this) the next refill is merged.
*/ */
#include <config.h>
#include <types.h> #include <types.h>
#include <util.h> #include <util.h>
#include <object/structures.h> #include <object/structures.h>
@@ -36,8 +37,8 @@
/* To do an operation in the kernel, the thread must have /* To do an operation in the kernel, the thread must have
* at least this much budget - see comment on refill_sufficient */ * at least this much budget - see comment on refill_sufficient */
#define MIN_BUDGET_US (2u * getKernelWcetUs()) #define MIN_BUDGET_US (2u * getKernelWcetUs() * CONFIG_KERNEL_WCET_SCALE)
#define MIN_BUDGET (2u * getKernelWcetTicks()) #define MIN_BUDGET (2u * getKernelWcetTicks() * CONFIG_KERNEL_WCET_SCALE)
/* Short hand for accessing refill queue items */ /* Short hand for accessing refill queue items */
#define REFILL_INDEX(sc, index) (((refill_t *) (SC_REF(sc) + sizeof(sched_context_t)))[index]) #define REFILL_INDEX(sc, index) (((refill_t *) (SC_REF(sc) + sizeof(sched_context_t)))[index])