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Add logic to drop the priority of the page fill task 

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2857 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2010-08-15 16:50:25 +00:00
parent 8d933821e4
commit 273f1971d4
4 changed files with 86 additions and 49 deletions
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24
Documentation/NuttXDemandPaging.html
View File

@ -160,7 +160,7 @@
<dl>
<dt><code>g_waitingforfill</code></dt>
<dd>An OS list that is used to hold the TCBs of tasks that are waiting for a page fill.</dd>
<dt><code>g_pendingfilltcb</code></dt>
<dt><code>g_pftcb</code></dt>
<dd>A variable that holds a reference to the TCB of the thread that is currently be re-filled.</dd>
<dt><code>g_pgworker</code></dt>
<dd>The <i>process</i> ID of of the thread that will perform the page fills.</dd>
@ -307,8 +307,8 @@
</p>
<p>
The page fill worker thread will maintain a static variable called <code>_TCB *g_pendingfilltcb</code>.
If no fill is in progress, <code>g_pendingfilltcb</code> will be NULL.
The page fill worker thread will maintain a static variable called <code>_TCB *g_pftcb</code>.
If no fill is in progress, <code>g_pftcb</code> will be NULL.
Otherwise, it will point to the TCB of the task which is receiving the fill that is in progess.
</p>
<ul><small>
@ -319,7 +319,7 @@
</small></ul>
<p>
When awakened from <code>pg_miss()</code>, no fill will be in progress and <code>g_pendingfilltcb</code> will be NULL.
When awakened from <code>pg_miss()</code>, no fill will be in progress and <code>g_pftcb</code> will be NULL.
In this case, the page fill worker thread will call <code>pg_startfill()</code>.
That function will perform the following operations:
<ul>
@ -387,10 +387,10 @@
In this non-blocking case, the callback <code>pg_callback()</code> will perform the following operations when it is notified that the fill has completed:
<ul>
<li>
Verify that <code>g_pendingfilltcb</code> is non-NULL.
Verify that <code>g_pftcb</code> is non-NULL.
</li>
<li>
Find the higher priority between the task waiting for the fill to complete in <code>g_pendingfilltcb</code> and the task waiting at the head of the <code>g_waitingforfill</code> list.
Find the higher priority between the task waiting for the fill to complete in <code>g_pftcb</code> and the task waiting at the head of the <code>g_waitingforfill</code> list.
That will be the priority of he highest priority task waiting for a fill.
</li>
<li>
@ -409,20 +409,20 @@
<a name="TaskResumption"><h2>Task Resumption</h2></a>
<p>
For the non-blocking <code>up_fillpage()</code>, the page fill worker thread will detect that the page fill is complete when it is awakened with <code>g_pendingfilltcb</code> non-NULL and fill completion status from <code>pg_callback</code>.
For the non-blocking <code>up_fillpage()</code>, the page fill worker thread will detect that the page fill is complete when it is awakened with <code>g_pftcb</code> non-NULL and fill completion status from <code>pg_callback</code>.
In the non-blocking case, the page fill worker thread will know that the page fill is complete when <code>up_fillpage()</code> returns.
</p>
<p>
In this either, the page fill worker thread will:
<ul>
<li>
Verify consistency of state information and <code>g_pendingfilltcb</code>.
Verify consistency of state information and <code>g_pftcb</code>.
</li>
<li>
Verify that the page fill completed successfully, and if so,
</li>
<li>
Call <code>up_unblocktask(g_pendingfilltcb)</code> to make the task that just received the fill ready-to-run.
Call <code>up_unblocktask(g_pftcb)</code> to make the task that just received the fill ready-to-run.
</li>
<li>
Check if the <code>g_waitingforfill</code> list is empty.
@ -432,10 +432,10 @@
Remove the highest priority task waiting for a page fill from <code>g_waitingforfill</code>,
</li>
<li>
Save the task's TCB in <code>g_pendingfilltcb</code>,
Save the task's TCB in <code>g_pftcb</code>,
</li>
<li>
If the priority of the thread in <code>g_pendingfilltcb</code>, is higher in priority than the default priority of the page fill worker thread, then set the priority of the page fill worker thread to that priority.
If the priority of the thread in <code>g_pftcb</code>, is higher in priority than the default priority of the page fill worker thread, then set the priority of the page fill worker thread to that priority.
</li>
<li>
Call <code>pg_startfill()</code> which will start the next fill (as described above).
@ -446,7 +446,7 @@
Otherwise,
<ul>
<li>
Set <code>g_pendingfilltcb</code> to NULL.
Set <code>g_pftcb</code> to NULL.
</li>
<li>
Restore the default priority of the page fill worker thread.

10
sched/pg_internal.h
View File

@ -87,10 +87,10 @@
extern pid_t g_pgworker;
/* The page fill worker thread maintains a static variable called
* g_pendingfilltcb. If no fill is in progress, g_pendingfilltcb will be NULL.
* Otherwise, g_pendingfile will point to the TCB of the task which is
* receiving the fill that is in progess.
/* The page fill worker thread maintains a static variable called g_pftcb.
* If no page fill is in progress, g_pftcb will be NULL. Otherwise, g_pftcb
* will point to the TCB of the task which is receiving the fill that is
* in progess.
*
* NOTE: I think that this is the only state in which a TCB does not reside
* in some list. Here is it in limbo, outside of the normally queuing while
@ -98,7 +98,7 @@ extern pid_t g_pgworker;
* TSTATE_TASK_INVALID.
*/
extern FAR _TCB *g_pendingfilltcb;
extern FAR _TCB *g_pftcb;
/****************************************************************************
* Public Function Prototypes

2
sched/pg_miss.c
View File

@ -166,7 +166,7 @@ void pg_miss(void)
* thread to start working on the queued page fill requests.
*/
if (!g_pendingfilltcb)
if (!g_pftcb)
{
kill(g_pgworker, SIGWORK);
}

99
sched/pg_worker.c
View File

@ -82,8 +82,8 @@
pid_t g_pgworker;
/* The page fill worker thread maintains a static variable called
* g_pendingfilltcb. If no fill is in progress, g_pendingfilltcb will be NULL.
* Otherwise, g_pendingfile will point to the TCB of the task which is
* g_pftcb. If no fill is in progress, g_pftcb will be NULL.
* Otherwise, g_pftcb will point to the TCB of the task which is
* receiving the fill that is in progess.
*
* NOTE: I think that this is the only state in which a TCB does not reside
@ -92,7 +92,7 @@ pid_t g_pgworker;
* TSTATE_TASK_INVALID.
*/
FAR _TCB *g_pendingfilltcb;
FAR _TCB *g_pftcb;
/****************************************************************************
* Private Variables
@ -132,9 +132,9 @@ status uint32_t g_starttime;
*
* When pg_callback() is called, it will perform the following operations:
*
* - Verify that g_pendingfilltcb is non-NULL.
* - Verify that g_pftcb is non-NULL.
* - Find the higher priority between the task waiting for the fill to
* complete in g_pendingfilltcb and the task waiting at the head of the
* complete in g_pftcb and the task waiting at the head of the
* g_waitingforfill list. That will be the priority of he highest priority
* task waiting for a fill.
* - If this higher priority is higher than current page fill worker thread,
@ -158,20 +158,20 @@ status uint32_t g_starttime;
#ifndef CONFIG_PAGING_BLOCKINGFILL
static void pg_callback(FAR _TCB *tcb, int result)
{
/* Verify that g_pendingfilltcb is non-NULL */
/* Verify that g_pftcb is non-NULL */
if (g_pendingfilltcb)
if (g_pftcb)
{
FAR _TCB *htcb = (FAR _TCB *)g_waitingforfill.head;
FAR _TCB *wtcb = sched_gettcb(g_pgworker);
/* Find the higher priority between the task waiting for the fill to
* complete in g_pendingfilltcb and the task waiting at the head of the
* complete in g_pftcb and the task waiting at the head of the
* g_waitingforfill list. That will be the priority of he highest
* priority task waiting for a fill.
*/
int priority = g_pendingfilltcb->sched_priority;
int priority = g_pftcb->sched_priority;
if (htcb && priority < htcb->sched_priority)
{
priority = htcb->sched_priority;
@ -218,14 +218,14 @@ static void pg_callback(FAR _TCB *tcb, int result)
* g_waitingforfill task list becomes empty.
*
* The result (NULL or a TCB pointer) will be returned in the global
* variable, g_pendingfilltcb.
* variable, g_pftcb.
*
* Input parameters:
* None
*
* Returned Value:
* If there are no further queue page fill operations to be performed,
* pg_startfill() will return false. Otherwise, it will return
* pg_dequeue() will return false. Otherwise, it will return
* true to that the full is in process (any errors will result in
* assertions and this function will not return).
*
@ -245,8 +245,8 @@ static inline bool pg_dequeue(void)
{
/* Remove the TCB from the head of the list (if any) */
g_pendingfilltcb = (FAR _TCB *)dq_remfirst((dq_queue_t*)&g_waitingforfill);
if (g_pendingfilltcb != NULL)
g_pftcb = (FAR _TCB *)dq_remfirst((dq_queue_t*)&g_waitingforfill);
if (g_pftcb != NULL)
{
/* Call the architecture-specific function up_checkmapping() to see if
* the page fill still needs to be performed. In certain conditions,
@ -255,10 +255,47 @@ static inline bool pg_dequeue(void)
* simply be restarted.
*/
if (!up_checkmapping(g_pendingfilltcb))
if (!up_checkmapping(g_pftcb))
{
/* This page needs to be filled. Return with g_pendingfilltcb
* holding the pointer to the TCB associated with task.
/* This page needs to be filled. pg_miss bumps up
* the priority of the page fill worker thread as each
* TCB is added to the g_waitingforfill list. So we
* may need to also drop the priority of the worker
* thread as the next TCB comes off of the list.
*
* If wtcb->sched_priority > CONFIG_PAGING_DEFPRIO,
* then the page fill worker thread is executing at
* an elevated priority that may be reduced.
*
* If wtcb->sched_priority > g_pftcb->sched_priority
* then the page fill worker thread is executing at
* a higher priority than is appropriate for this
* fill (this priority can get re-boosted by pg_miss()
* if a new higher priority fill is required).
*/
FAR _TCB *wtcb = (FAR _TCB *)g_readytorun.head;
if (wtcb->sched_priority > CONFIG_PAGING_DEFPRIO &&
wtcb->sched_priority > g_pftcb->sched_priority)
{
/* Don't reduce the priority of the page fill
* worker thread lower than the configured
* minimum.
*/
int priority = g_pftcb->sched_priority;
if (priority < CONFIG_PAGING_DEFPRIO)
{
priority = CONFIG_PAGING_DEFPRIO;
}
/* Reduce the priority of the page fill worker thread */
sched_setpriority(wtcb, priority);
}
/* Return with g_pftcb holding the pointer to
* the TCB associated with task that requires the page fill.
*/
return true;
@ -268,10 +305,10 @@ static inline bool pg_dequeue(void)
* virtual address space -- just restart it.
*/
up_unblock_task(g_pendingfilltcb);
up_unblock_task(g_pftcb);
}
}
while (g_pendingfilltcb != NULL);
while (g_pftcb != NULL);
return false;
}
@ -323,7 +360,7 @@ static inline bool pg_startfill(void)
* a page in-use, un-map it, and make it available.
*/
result = up_allocpage(g_pendingfilltcb, &vpage);
result = up_allocpage(g_pftcb, &vpage);
DEBUGASSERT(result == OK);
/* Start the fill. The exact way that the fill is started depends upon
@ -339,7 +376,7 @@ static inline bool pg_startfill(void)
* status of the fill will be provided by return value from up_fillpage().
*/
result = up_fillpage(g_pendingfilltcb, vpage);
result = up_fillpage(g_pftcb, vpage);
DEBUGASSERT(result == OK);
#else
/* If CONFIG_PAGING_BLOCKINGFILL is defined, then up_fillpage is non-blocking
@ -351,7 +388,7 @@ static inline bool pg_startfill(void)
* This callback will probably from interrupt level.
*/
result = up_fillpage(g_pendingfilltcb, vpage, pg_callback);
result = up_fillpage(g_pftcb, vpage, pg_callback);
DEBUGASSERT(result == OK);
/* Save the time that the fill was started. These will be used to check for
@ -387,7 +424,7 @@ static inline bool pg_startfill(void)
*
* This functin will perform the following operations:
*
* - Set g_pendingfilltcb to NULL.
* - Set g_pftcb to NULL.
* - Restore the default priority of the page fill worker thread.
*
* Input parameters:
@ -405,7 +442,7 @@ static inline bool pg_startfill(void)
static inline void pg_alldone(void)
{
FAR _TCB *wtcb = (FAR _TCB *)g_readytorun.head;
g_pendingfilltcb = NULL;
g_pftcb = NULL;
sched_setpriority(wtcb, CONFIG_PAGING_DEFPRIO);
}
@ -436,11 +473,11 @@ static inline void pg_alldone(void)
static inline void pg_fillcomplete(void)
{
/* Call up_unblocktask(g_pendingfilltcb) to make the task that just
/* Call up_unblocktask(g_pftcb) to make the task that just
* received the fill ready-to-run.
*/
up_unblock_task(g_pendingfilltcb);
up_unblock_task(g_pftcb);
}
/****************************************************************************
@ -510,11 +547,11 @@ int pg_worker(int argc, char *argv[])
#ifdef CONFIG_PAGING_BLOCKINGFILL
/* For the non-blocking up_fillpage(), the page fill worker thread will detect
* that the page fill is complete when it is awakened with g_pendingfilltcb non-NULL
* that the page fill is complete when it is awakened with g_pftcb non-NULL
* and fill completion status from pg_callback.
*/
if (g_pendingfilltcb != NULL)
if (g_pftcb != NULL)
{
/* If it is a real page fill completion event, then the result of the page
* fill will be in g_fillresult and will not be equal to -EBUSY.
@ -530,7 +567,7 @@ int pg_worker(int argc, char *argv[])
* task that was blocked waiting for this page fill.
*/
up_unblock_task(g_pendingfilltcb);;
up_unblock_task(g_pftcb);;
/* Yes .. Start the next asynchronous fill. Check the return
* value to see a fill was actually started (false means that
@ -563,14 +600,14 @@ int pg_worker(int argc, char *argv[])
/* Otherwise, this might be a page fill initiation event. When
* awakened from pg_miss(), no fill will be in progress and
* g_pendingfilltcb will be NULL.
* g_pftcb will be NULL.
*/
else
{
/* Are there tasks blocked and waiting for a fill? If so,
* pg_startfill() will start the asynchronous fill (and set
* g_pendingfilltcb).
* g_pftcb).
*/
(void)pg_startfill();
@ -601,7 +638,7 @@ int pg_worker(int argc, char *argv[])
* returns true.
*/
up_unblock_task(g_pendingfilltcb);;
up_unblock_task(g_pftcb);;
}
/* All queued fills have been processed */