WebSVN – HelenOS-historic – Diff – /uspace/trunk/libc/generic/psthread.c

 /*
  * Copyright (C) 2006 Ondrej Palkovsky
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include <libadt/list.h>
 #include <psthread.h>
 #include <malloc.h>
 #include <unistd.h>
 #include <thread.h>
 #include <stdio.h>
 #include <kernel/arch/faddr.h>
 #include <futex.h>
 #include <assert.h>
 #include <async.h>
 #ifndef PSTHREAD_INITIAL_STACK_PAGES_NO
 #define PSTHREAD_INITIAL_STACK_PAGES_NO 1
 #endif
 static LIST_INITIALIZE(ready_list);
+static LIST_INITIALIZE(serialized_list);
 static LIST_INITIALIZE(manager_list);
 static void psthread_exit(void) __attribute__ ((noinline));
 static void psthread_main(void);
 static atomic_t psthread_futex = FUTEX_INITIALIZER;
+/** Count of real threads that are in async_serialized mode */
+static int serialized_threads; /* Protected by async_futex */
+/** Thread-local count of serialization. If >0, we must not preempt */
+static __thread serialization_count;
+/** Counter of threads residing in async_manager */
+static int threads_in_manager;
 /** Setup PSthread information into TCB structure */
 psthread_data_t * psthread_setup()
+{
     psthread_data_t *pt;
     tcb_t *tcb;
     tcb = __make_tls();
     if (!tcb)
         return NULL;
     pt = malloc(sizeof(*pt));
     if (!pt) {
         __free_tls(tcb);
         return NULL;
+    }
     tcb->pst_data = pt;
     pt->tcb = tcb;
     return pt;
+}
 void psthread_teardown(psthread_data_t *pt)
+{
     __free_tls(pt->tcb);
     free(pt);
+}
-/** Function to preempt to other pseudo thread without adding
- * currently running pseudo thread to ready_list.
- */
-void psthread_exit(void)
-{
-    psthread_data_t *pt;
-    futex_down(&psthread_futex);
-    if (!list_empty(&ready_list))
-        pt = list_get_instance(ready_list.next, psthread_data_t, link);
-    else if (!list_empty(&manager_list))
-        pt = list_get_instance(manager_list.next, psthread_data_t, link);
-    else {
-        printf("Cannot find suitable psthread to run.\n");
-        _exit(0);
-    }
-    list_remove(&pt->link);
-    futex_up(&psthread_futex);
-    context_restore(&pt->ctx);
-    /* Never reached */
-}
 /** Function that is called on entry to new uspace thread */
 void psthread_main(void)
+{
     psthread_data_t *pt = __tcb_get()->pst_data;
+    serialization_count = 0; // TODO: WHY HERE?
     pt->retval = pt->func(pt->arg);
     pt->finished = 1;
     if (pt->waiter)
         list_append(&pt->waiter->link, &ready_list);
-    psthread_exit();
+    psthread_schedule_next_adv(PS_FROM_DEAD);
+}
 /** Schedule next userspace pseudo thread.
+ *
  * If calling with PS_TO_MANAGER parameter, the async_futex should be
  * held.
+ *
  * @param tomanager If true, we are switching to next ready manager thread
  *                  (if none is found, thread is exited)
  * @param frommanager If true, we are switching from manager thread
  * @return 0 if there is no ready pseudo thread, 1 otherwise.
  */
 int psthread_schedule_next_adv(pschange_type ctype)
+{
-    psthread_data_t *pt;
+    psthread_data_t *srcpt, *dstpt;
     int retval = 0;
     futex_down(&psthread_futex);
     if (ctype == PS_PREEMPT && list_empty(&ready_list))
         goto ret_0;
+    if (ctype == PS_FROM_MANAGER) {
-    if (ctype == PS_FROM_MANAGER && list_empty(&ready_list)) {
+        if (list_empty(&ready_list) && list_empty(&serialized_list))
+            goto ret_0;
+        /* Do not preempt if there is not sufficient count of thread managers */
+        if (list_empty(&serialized_list) && threads_in_manager <= serialized_threads) {
-        goto ret_0;
+            goto ret_0;
+        }
+    }
     /* If we are going to manager and none exists, create it */
-    while (ctype == PS_TO_MANAGER && list_empty(&manager_list)) {
+    if (ctype == PS_TO_MANAGER || ctype == PS_FROM_DEAD) {
+        while (list_empty(&manager_list)) {
-        futex_up(&psthread_futex);
+            futex_up(&psthread_futex);
-        async_create_manager();
+            async_create_manager();
-        futex_down(&psthread_futex);
+            futex_down(&psthread_futex);
+        }
+    }
+    if (ctype != PS_FROM_DEAD) {
+        /* Save current state */
+        srcpt = __tcb_get()->pst_data;
+        if (!context_save(&srcpt->ctx)) {
+            if (serialization_count)
+                srcpt->flags &= ~PSTHREAD_SERIALIZED;
+            return 1; // futex_up already done here
+        }
-    pt = __tcb_get()->pst_data;
+        /* Save myself to correct run list */
-    if (!context_save(&pt->ctx))
+        if (ctype == PS_PREEMPT)
-        return 1; // futex_up already done here
+            list_append(&srcpt->link, &ready_list);
+        else if (ctype == PS_FROM_MANAGER) {
+            list_append(&srcpt->link, &manager_list);
+            threads_in_manager--;
+        } /* If ctype == PS_TO_MANAGER, don't save ourselves to any list, we should
+           * already be somewhere, or we will be lost */
+    }
+    /* Choose new thread to run */
-    if (ctype == PS_PREEMPT)
+    if (ctype == PS_TO_MANAGER || ctype == PS_FROM_DEAD) {
-        list_append(&pt->link, &ready_list);
+        dstpt = list_get_instance(manager_list.next,psthread_data_t, link);
-    else if (ctype == PS_FROM_MANAGER)
+        if (serialization_count && ctype == PS_TO_MANAGER) {
+            serialized_threads++;
-        list_append(&pt->link, &manager_list);
+            srcpt->flags |= PSTHREAD_SERIALIZED;
+        }
+        threads_in_manager++;
+    } else {
-    if (ctype == PS_TO_MANAGER)
+        if (!list_empty(&serialized_list)) {
-        pt = list_get_instance(manager_list.next,psthread_data_t, link);
+            dstpt = list_get_instance(serialized_list.next, psthread_data_t, link);
+            serialized_threads--;
-    else
+        } else
-        pt = list_get_instance(ready_list.next, psthread_data_t, link);
+            dstpt = list_get_instance(ready_list.next, psthread_data_t, link);
+    }
-    list_remove(&pt->link);
+    list_remove(&dstpt->link);
     futex_up(&psthread_futex);
-    context_restore(&pt->ctx);
+    context_restore(&dstpt->ctx);
 ret_0:
     futex_up(&psthread_futex);
     return retval;
+}
 /** Wait for uspace pseudo thread to finish.
+ *
  * @param psthrid Pseudo thread to wait for.
+ *
  * @return Value returned by the finished thread.
  */
 int psthread_join(pstid_t psthrid)
+{
     volatile psthread_data_t *pt, *mypt;
     volatile int retval;
     /* Handle psthrid = Kernel address -> it is wait for call */
     pt = (psthread_data_t *) psthrid;
-    if (!pt->finished) {
+    /* TODO */
-        mypt = __tcb_get()->pst_data;
+    printf("join unsupported\n");
-        if (context_save(&((psthread_data_t *) mypt)->ctx)) {
-            pt->waiter = (psthread_data_t *) mypt;
-            psthread_exit();
+    _exit(1);
-        }
-    }
     retval = pt->retval;
     free(pt->stack);
     psthread_teardown((void *)pt);
     return retval;
+}
 /**
  * Create a userspace thread
+ *
  * @param func Pseudo thread function.
  * @param arg Argument to pass to func.
+ *
  * @return 0 on failure, TLS of the new pseudo thread.
  */
 pstid_t psthread_create(int (*func)(void *), void *arg)
+{
     psthread_data_t *pt;
     pt = psthread_setup();
     if (!pt)
         return 0;
     pt->stack = (char *) malloc(PSTHREAD_INITIAL_STACK_PAGES_NO*getpagesize());
     if (!pt->stack) {
         psthread_teardown(pt);
         return 0;
+    }
     pt->arg= arg;
     pt->func = func;
     pt->finished = 0;
     pt->waiter = NULL;
+    pt->flags = 0;
     context_save(&pt->ctx);
     context_set(&pt->ctx, FADDR(psthread_main), pt->stack, PSTHREAD_INITIAL_STACK_PAGES_NO*getpagesize(),
             pt->tcb);
     return (pstid_t )pt;
+}
 /** Add a thread to ready list */
 void psthread_add_ready(pstid_t psthrid)
+{
     psthread_data_t *pt;
     pt = (psthread_data_t *) psthrid;
     futex_down(&psthread_futex);
+    if ((pt->flags & PSTHREAD_SERIALIZED))
+        list_append(&pt->link, &serialized_list);
+    else
-    list_append(&pt->link, &ready_list);
+        list_append(&pt->link, &ready_list);
     futex_up(&psthread_futex);
+}
 /** Add a thread to manager list */
 void psthread_add_manager(pstid_t psthrid)
+{
     psthread_data_t *pt;
     pt = (psthread_data_t *) psthrid;
     futex_down(&psthread_futex);
     list_append(&pt->link, &manager_list);
     futex_up(&psthread_futex);
+}
 /** Remove one manager from manager list */
 void psthread_remove_manager()
+{
     futex_down(&psthread_futex);
     if (list_empty(&manager_list)) {
         futex_up(&psthread_futex);
         return;
+    }
     list_remove(manager_list.next);
     futex_up(&psthread_futex);
+}
 /** Return thread id of current running thread */
 pstid_t psthread_get_id(void)
+{
     return (pstid_t)__tcb_get()->pst_data;
+}
+/** Disable preemption
+ *
+ * If the thread wants to send several message in row and does not want
+ * to be preempted, it should start async_serialize_start() in the beginning
+ * of communication and async_serialize_end() in the end. If it is a
+ * true multithreaded application, it should protect the communication channel
+ * by a futex as well. Interrupt messages will can still be preempted.
+ */
+void psthread_inc_sercount(void)
+{
+    serialization_count++;
+}
+void psthread_dec_sercount(void)
+{
+    serialization_count--;
+}

Subversion Repositories HelenOS-historic

(root)/uspace/trunk/libc/generic/psthread.c – Rev 1427 → 1610