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Kernel optimisations.

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Richard Barry 2013-07-12 11:11:19 +00:00
parent c9d9bddc3c
commit ad8fa53043
5 changed files with 224 additions and 206 deletions
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80
FreeRTOS/Source/include/list.h
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@ -56,19 +56,19 @@
***************************************************************************
http://www.FreeRTOS.org - Documentation, books, training, latest versions,
http://www.FreeRTOS.org - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details.
http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, and our new
fully thread aware and reentrant UDP/IP stack.
http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems, who sell the code with commercial support,
http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems, who sell the code with commercial support,
indemnification and middleware, under the OpenRTOS brand.
http://www.SafeRTOS.com - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
http://www.SafeRTOS.com - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
*/
@ -104,6 +104,38 @@
#ifndef LIST_H
#define LIST_H
/*
* The list structure members are modified from within interrupts, and therefore
* by rights should be declared volatile. However, they are only modified in a
* functionally atomic way (within critical sections of with the scheduler
* suspended) and are either passed by reference into a function or indexed via
* a volatile variable. Therefore, in all use cases tested so far, the volatile
* qualifier can be omitted in order to provide a moderate performance
* improvement without adversely affecting functional behaviour. The assembly
* instructions generated by the IAR, ARM and GCC compilers when the respective
* compiler's options were set for maximum optimisation has been inspected and
* deemed to be as intended. That said, as compiler technology advances, and
* especially if aggressive cross module optimisation is used (a use case that
* has not been exercised to any great extend) then it is feasible that the
* volatile qualifier will be needed for correct optimisation. It is expected
* that a compiler removing essential code because, without the volatile
* qualifier on the list structure members and with aggressive cross module
* optimisation, the compiler deemed the code unnecessary will result in
* complete and obvious failure of the scheduler. If this is ever experienced
* then the volatile qualifier can be inserted in the relevant places within the
* list structures by simply defining configLIST_VOLATILE to volatile in
* FreeRTOSConfig.h (as per the example at the bottom of this comment block).
* If configLIST_VOLATILE is not defined then the preprocessor directives below
* will simply #define configLIST_VOLATILE away completely.
*
* To use volatile list structure members then add the following line to
* FreeRTOSConfig.h (without the quotes):
* "#define configLIST_VOLATILE volatile"
*/
#ifndef configLIST_VOLATILE
#define configLIST_VOLATILE
#endif /* configSUPPORT_CROSS_MODULE_OPTIMISATION */
#ifdef __cplusplus
extern "C" {
#endif
@ -112,19 +144,19 @@ extern "C" {
*/
struct xLIST_ITEM
{
portTickType xItemValue; /*< The value being listed. In most cases this is used to sort the list in descending order. */
volatile struct xLIST_ITEM * pxNext; /*< Pointer to the next xListItem in the list. */
volatile struct xLIST_ITEM * pxPrevious;/*< Pointer to the previous xListItem in the list. */
void * pvOwner; /*< Pointer to the object (normally a TCB) that contains the list item. There is therefore a two way link between the object containing the list item and the list item itself. */
void * pvContainer; /*< Pointer to the list in which this list item is placed (if any). */
configLIST_VOLATILE portTickType xItemValue; /*< The value being listed. In most cases this is used to sort the list in descending order. */
struct xLIST_ITEM * configLIST_VOLATILE pxNext; /*< Pointer to the next xListItem in the list. */
struct xLIST_ITEM * configLIST_VOLATILE pxPrevious;/*< Pointer to the previous xListItem in the list. */
void * pvOwner; /*< Pointer to the object (normally a TCB) that contains the list item. There is therefore a two way link between the object containing the list item and the list item itself. */
void * configLIST_VOLATILE pvContainer; /*< Pointer to the list in which this list item is placed (if any). */
};
typedef struct xLIST_ITEM xListItem; /* For some reason lint wants this as two separate definitions. */
typedef struct xLIST_ITEM xListItem; /* For some reason lint wants this as two separate definitions. */
struct xMINI_LIST_ITEM
{
portTickType xItemValue;
volatile struct xLIST_ITEM *pxNext;
volatile struct xLIST_ITEM *pxPrevious;
configLIST_VOLATILE portTickType xItemValue;
struct xLIST_ITEM * configLIST_VOLATILE pxNext;
struct xLIST_ITEM * configLIST_VOLATILE pxPrevious;
};
typedef struct xMINI_LIST_ITEM xMiniListItem;
@ -133,9 +165,9 @@ typedef struct xMINI_LIST_ITEM xMiniListItem;
*/
typedef struct xLIST
{
volatile unsigned portBASE_TYPE uxNumberOfItems;
volatile xListItem * pxIndex; /*< Used to walk through the list. Points to the last item returned by a call to pvListGetOwnerOfNextEntry (). */
volatile xMiniListItem xListEnd; /*< List item that contains the maximum possible item value meaning it is always at the end of the list and is therefore used as a marker. */
configLIST_VOLATILE unsigned portBASE_TYPE uxNumberOfItems;
xListItem * configLIST_VOLATILE pxIndex; /*< Used to walk through the list. Points to the last item returned by a call to pvListGetOwnerOfNextEntry (). */
xMiniListItem xListEnd; /*< List item that contains the maximum possible item value meaning it is always at the end of the list and is therefore used as a marker. */
} xList;
/*
@ -286,7 +318,7 @@ xList * const pxConstList = ( pxList ); \
* \page vListInitialise vListInitialise
* \ingroup LinkedList
*/
void vListInitialise( xList *pxList );
void vListInitialise( xList * const pxList );
/*
* Must be called before a list item is used. This sets the list container to
@ -297,7 +329,7 @@ void vListInitialise( xList *pxList );
* \page vListInitialiseItem vListInitialiseItem
* \ingroup LinkedList
*/
void vListInitialiseItem( xListItem *pxItem );
void vListInitialiseItem( xListItem * const pxItem );
/*
* Insert a list item into a list. The item will be inserted into the list in
@ -310,7 +342,7 @@ void vListInitialiseItem( xListItem *pxItem );
* \page vListInsert vListInsert
* \ingroup LinkedList
*/
void vListInsert( xList *pxList, xListItem *pxNewListItem );
void vListInsert( xList * const pxList, xListItem * const pxNewListItem );
/*
* Insert a list item into a list. The item will be inserted in a position
@ -331,7 +363,7 @@ void vListInsert( xList *pxList, xListItem *pxNewListItem );
* \page vListInsertEnd vListInsertEnd
* \ingroup LinkedList
*/
void vListInsertEnd( xList *pxList, xListItem *pxNewListItem );
void vListInsertEnd( xList * const pxList, xListItem * const pxNewListItem );
/*
* Remove an item from a list. The list item has a pointer to the list that
@ -339,14 +371,14 @@ void vListInsertEnd( xList *pxList, xListItem *pxNewListItem );
*
* @param uxListRemove The item to be removed. The item will remove itself from
* the list pointed to by it's pxContainer parameter.
*
*
* @return The number of items that remain in the list after the list item has
* been removed.
*
* \page uxListRemove uxListRemove
* \ingroup LinkedList
*/
unsigned portBASE_TYPE uxListRemove( xListItem *pxItemToRemove );
unsigned portBASE_TYPE uxListRemove( xListItem * const pxItemToRemove );
#ifdef __cplusplus
}