X-Git-Url: https://pd.if.org/git/?p=nbds;a=blobdiff_plain;f=runtime%2Frcu.c;h=0d65a37f6dda8bca88b9e40e634a663b7637f776;hp=897bdffdedd0e70cbec5351686a5dca210c27ba6;hb=HEAD;hpb=d791fc64b23a9c0a3ed90aa60571344d7735aee9

diff --git a/runtime/rcu.c b/runtime/rcu.c
index 897bdff..0d65a37 100644
--- a/runtime/rcu.c
+++ b/runtime/rcu.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * Written by Josh Dybnis and released to the public domain, as explained at
  * http://creativecommons.org/licenses/publicdomain
  *
@@ -12,6 +12,7 @@
 #include "lwt.h"
 #include "mem.h"
 #include "tls.h"
+#include "rcu.h"
 
 #define RCU_POST_THRESHOLD 10
 #define RCU_QUEUE_SCALE 20
@@ -23,13 +24,14 @@ typedef struct fifo {
     void *x[0];
 } fifo_t;
 
+#define MOD_SCALE(x, b) ((x) & MASK(b))
 static uint64_t rcu_[MAX_NUM_THREADS][MAX_NUM_THREADS] = {};
 static uint64_t rcu_last_posted_[MAX_NUM_THREADS][MAX_NUM_THREADS] = {};
 static fifo_t *pending_[MAX_NUM_THREADS] = {};
 static int num_threads_ = 0;
 
 static fifo_t *fifo_alloc(int scale) {
-    fifo_t *q = (fifo_t *)nbd_malloc(sizeof(fifo_t) + (1 << scale) * sizeof(void *)); 
+    fifo_t *q = (fifo_t *)nbd_malloc(sizeof(fifo_t) + (1ULL << scale) * sizeof(void *));
     memset(q, 0, sizeof(fifo_t));
     q->scale = scale;
     q->head = 0;
@@ -37,66 +39,56 @@ static fifo_t *fifo_alloc(int scale) {
     return q;
 }
 
-static uint32_t fifo_index (fifo_t *q, uint32_t i) {
-    return i & MASK(q->scale);
-}
-
-static void fifo_enqueue (fifo_t *q, void *x) {
-    assert(fifo_index(q, q->head + 1) != fifo_index(q, q->tail));
-    uint32_t i = fifo_index(q, q->head++);
-    q->x[i] = x;
-}
-
-static void *fifo_dequeue (fifo_t *q) {
-    uint32_t i = fifo_index(q, q->tail++);
-    return q->x[i];
-}
-
-void rcu_thread_init (int id) {
-    assert(id < MAX_NUM_THREADS);
-    if (pending_[id] == NULL) {
-        pending_[id] = fifo_alloc(RCU_QUEUE_SCALE);
-        SYNC_ADD(&num_threads_, 1);
+void rcu_thread_init (void) {
+    int thread_index = GET_THREAD_INDEX();
+    if (pending_[thread_index] == NULL) {
+        pending_[thread_index] = fifo_alloc(RCU_QUEUE_SCALE);
+        (void)SYNC_ADD(&num_threads_, 1);
     }
 }
 
-static void rcu_post (uint64_t x) {
-    LOCALIZE_THREAD_LOCAL(tid_, int);
-    if (x - rcu_last_posted_[tid_][tid_] < RCU_POST_THRESHOLD)
-        return;
-
-    int next_thread_id = (tid_ + 1) % num_threads_;
-
-    TRACE("r0", "rcu_post: %llu", x, 0);
-    rcu_[next_thread_id][tid_] = rcu_last_posted_[tid_][tid_] = x;
-}
-
 void rcu_update (void) {
-    LOCALIZE_THREAD_LOCAL(tid_, int);
-    assert(tid_ < num_threads_);
-    int next_thread_id = (tid_ + 1) % num_threads_;
+    int thread_index = GET_THREAD_INDEX();
+    int next_thread_index = (thread_index + 1) % num_threads_;
+    TRACE("r1", "rcu_update: updating thread %llu", next_thread_index, 0);
     int i;
     for (i = 0; i < num_threads_; ++i) {
-        if (i == tid_)
+        if (i == thread_index)
             continue;
 
         // No need to post an update if the value hasn't changed
-        if (rcu_[tid_][i] == rcu_last_posted_[tid_][i])
+        if (rcu_[thread_index][i] == rcu_last_posted_[thread_index][i])
             continue;
 
-        uint64_t x = rcu_[tid_][i];
-        rcu_[next_thread_id][i] = rcu_last_posted_[tid_][i] = x;
+        uint64_t x = rcu_[thread_index][i];
+        rcu_[next_thread_index][i] = rcu_last_posted_[thread_index][i] = x;
+        TRACE("r2", "rcu_update: posted updated value (%llu) for thread %llu", x, i);
     }
 
     // free
-    while (pending_[tid_]->tail != rcu_[tid_][tid_]) {
-        nbd_free(fifo_dequeue(pending_[tid_]));
+    fifo_t *q = pending_[thread_index];
+    while (q->tail != rcu_[thread_index][thread_index]) {
+        uint32_t i = MOD_SCALE(q->tail, q->scale);
+        TRACE("r0", "rcu_update: freeing %p from queue at position %llu", q->x[i], q->tail);
+        nbd_free(q->x[i]);
+        q->tail++;
     }
 }
 
-void nbd_defer_free (void *x) {
-    LOCALIZE_THREAD_LOCAL(tid_, int);
-    fifo_enqueue(pending_[tid_], x);
-    TRACE("r0", "nbd_defer_free: put %p on queue at position %llu", x, pending_[tid_]->head);
-    rcu_post(pending_[tid_]->head);
+void rcu_defer_free (void *x) {
+    assert(x);
+    int thread_index = GET_THREAD_INDEX();
+    fifo_t *q = pending_[thread_index];
+    assert(MOD_SCALE(q->head + 1, q->scale) != MOD_SCALE(q->tail, q->scale));
+    uint32_t i = MOD_SCALE(q->head, q->scale);
+    q->x[i] = x;
+    TRACE("r0", "rcu_defer_free: put %p on queue at position %llu", x, q->head);
+    q->head++;
+
+    if (pending_[thread_index]->head - rcu_last_posted_[thread_index][thread_index] >= RCU_POST_THRESHOLD) {
+        TRACE("r0", "rcu_defer_free: posting %llu", pending_[thread_index]->head, 0);
+        int next_thread_index = (thread_index + 1) % num_threads_;
+        rcu_[next_thread_index][thread_index] = pending_[thread_index]->head;
+        rcu_last_posted_[thread_index][thread_index] = pending_[thread_index]->head;
+    }
 }