sched/tcb: reduce kthread overheads

This patch uses shared group for kthreads to reduce overhead. see pull/12320 for more info. Signed-off-by: Yanfeng Liu <[email protected]>
yf13 · May 12, 2024 · 7270ad8 · 7270ad8
1 parent b47a361
commit 7270ad8
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Showing 3 changed files with 34 additions and 10 deletions.
diff --git a/sched/group/group_create.c b/sched/group/group_create.c
@@ -40,9 +40,11 @@
 #include "tls/tls.h"
 
 /****************************************************************************
- * Public Data
+ * Private Data
  ****************************************************************************/
 
+static struct task_group_s  g_kthread_group;   /* Shared among kthreads     */
+
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -119,9 +121,23 @@ int group_initialize(FAR struct task_tcb_s *tcb, uint8_t ttype)
 
   DEBUGASSERT(tcb && !tcb->cmn.group);
 
+  ttype &= TCB_FLAG_TTYPE_MASK;
+
+  if (ttype == TCB_FLAG_TTYPE_KERNEL && g_kthread_group.tg_info)
+    {
+      tcb->cmn.group = &g_kthread_group;
+      return OK;
+    }
+
+  if (NULL == g_kthread_group.tg_info)
+    {
+      sinfo("group=%zu task=%zu kthread=%zu\n", sizeof(*group),
+            sizeof(struct task_tcb_s), sizeof(struct tcb_s));
+    }
+
   /* Allocate the group structure and assign it to the TCB */
 
-  group = &tcb->group;
+  group = (ttype == TCB_FLAG_TTYPE_KERNEL) ? &g_kthread_group : &tcb->group;
 
 #if defined(CONFIG_MM_KERNEL_HEAP)
   /* If this group is being created for a privileged thread, then all

diff --git a/sched/init/nx_start.c b/sched/init/nx_start.c
@@ -205,7 +205,7 @@ uint8_t g_nx_initstate;  /* See enum nx_initstate_e */
  * bringing up the rest of the system.
  */
 
-static struct task_tcb_s g_idletcb[CONFIG_SMP_NCPUS];
+static struct tcb_s g_idletcb[CONFIG_SMP_NCPUS];
 
 /* This is the name of the idle task */
 
@@ -352,11 +352,14 @@ static void idle_task_initialize(void)
 {
   FAR struct task_tcb_s *tcb;
   FAR dq_queue_t *tasklist;
+  volatile uintptr_t p;
   int i;
 
+  memset(g_idletcb, 0, sizeof(g_idletcb));
   for (i = 0; i < CONFIG_SMP_NCPUS; i++)
     {
-      tcb = &g_idletcb[i];
+      p = (uintptr_t)&g_idletcb[i];
+      tcb = (FAR struct task_tcb_s *)p;
 
       /* Initialize a TCB for this thread of execution.  NOTE:  The default
        * value for most components of the g_idletcb are zero.  The entire
@@ -365,7 +368,6 @@ static void idle_task_initialize(void)
        * that has pid == 0 and sched_priority == 0.
        */
 
-      memset(tcb, 0, sizeof(struct task_tcb_s));
       tcb->cmn.pid        = i;
       tcb->cmn.task_state = TSTATE_TASK_RUNNING;
 
@@ -460,14 +462,16 @@ static void idle_task_initialize(void)
 static void idle_group_initialize(void)
 {
   FAR struct task_tcb_s *tcb;
+  volatile uintptr_t p;
   int hashndx;
   int i;
 
   /* Assign the process ID(s) of ZERO to the idle task(s) */
 
   for (i = 0; i < CONFIG_SMP_NCPUS; i++)
     {
-      tcb = &g_idletcb[i];
+      p = (uintptr_t)&g_idletcb[i];
+      tcb = (FAR struct task_tcb_s *)p;
 
       hashndx = PIDHASH(i);
       nxsched_pidhash()[hashndx] = &tcb->cmn;
@@ -533,6 +537,7 @@ static void idle_group_initialize(void)
 
 void nx_start(void)
 {
+  FAR struct task_tcb_s *ttcb;
   int i;
 
   sinfo("Entry\n");
@@ -727,17 +732,18 @@ void nx_start(void)
 
   /* Announce that the CPU0 IDLE task has started */
 
-  sched_note_start(&g_idletcb[0].cmn);
+  sched_note_start(&g_idletcb[0]);
 
   /* Initialize stdio for the IDLE task of each CPU */
 
   for (i = 0; i < CONFIG_SMP_NCPUS; i++)
     {
+      ttcb = (FAR struct task_tcb_s *)&g_idletcb[i];
       if (i > 0)
         {
           /* Clone stdout, stderr, stdin from the CPU0 IDLE task. */
 
-          DEBUGVERIFY(group_setuptaskfiles(&g_idletcb[i], NULL, true));
+          DEBUGVERIFY(group_setuptaskfiles(ttcb, NULL, true));
         }
       else
         {

diff --git a/sched/task/task_create.c b/sched/task/task_create.c
@@ -78,11 +78,13 @@ int nxthread_create(FAR const char *name, uint8_t ttype, int priority,
 {
   FAR struct task_tcb_s *tcb;
   pid_t pid;
-  int ret;
+  volatile int ret;
 
   /* Allocate a TCB for the new task. */
 
-  tcb = kmm_zalloc(sizeof(struct task_tcb_s));
+  ret = (ttype == TCB_FLAG_TTYPE_KERNEL) ? sizeof(struct tcb_s) :
+                                           sizeof(*tcb);
+  tcb = kmm_zalloc(ret);
   if (!tcb)
     {
       serr("ERROR: Failed to allocate TCB\n");