X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=util%2Frcu.c;fp=util%2Frcu.c;h=0000000000000000000000000000000000000000;hb=efd90a1b8a9d3bbb1bdd8e6ae41b3462e7193fb2;hp=dfa49c8652ed277de7eb847716bd61d0f21e96a5;hpb=69f813b01bb0472f9ec5368b26a702bcc06f7e29;p=nbds

diff --git a/util/rcu.c b/util/rcu.c
deleted file mode 100644
index dfa49c8..0000000
--- a/util/rcu.c
+++ /dev/null
@@ -1,211 +0,0 @@
-/* 
- * Written by Josh Dybnis and released to the public domain, as explained at
- * http://creativecommons.org/licenses/publicdomain
- *
- * safe memory reclemation using a simple technique from rcu
- */
-#include <string.h>
-#include "common.h"
-#include "rcu.h"
-#include "lwt.h"
-#include "mem.h"
-#include "nbd.h"
-#include "tls.h"
-
-#define RCU_POST_THRESHOLD 10
-#define RCU_QUEUE_SCALE 20
-
-typedef struct fifo {
-    uint32_t head;
-    uint32_t tail;
-    uint32_t scale;
-    void *x[0];
-} fifo_t;
-
-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 *)); 
-    memset(q, 0, sizeof(fifo_t));
-    q->scale = scale;
-    q->head = 0;
-    q->tail = 0;
-    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);
-    }
-}
-
-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 i;
-    for (i = 0; i < num_threads_; ++i) {
-        if (i == tid_)
-            continue;
-
-        // No need to post an update if the value hasn't changed
-        if (rcu_[tid_][i] == rcu_last_posted_[tid_][i])
-            continue;
-
-        uint64_t x = rcu_[tid_][i];
-        rcu_[next_thread_id][i] = rcu_last_posted_[tid_][i] = x;
-    }
-
-    // free
-    while (pending_[tid_]->tail != rcu_[tid_][tid_]) {
-        nbd_free(fifo_dequeue(pending_[tid_]));
-    }
-}
-
-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);
-}
-
-#ifdef MAKE_rcu_test
-#include <pthread.h>
-#include <errno.h>
-#include <stdio.h>
-
-#define NUM_ITERATIONS 10000000
-
-typedef struct node {
-    struct node *next;
-} node_t;
-
-typedef struct lifo {
-    node_t *head;
-} lifo_t;
-
-static volatile int wait_;
-static lifo_t *stk_;
-
-static lifo_t *lifo_alloc (void) {
-    lifo_t *stk = (lifo_t *)nbd_malloc(sizeof(lifo_t)); 
-    memset(stk, 0, sizeof(lifo_t));
-    return stk;
-}
-
-static void lifo_aba_push (lifo_t *stk, node_t *x) {
-    node_t *head;
-    do {
-        head = ((volatile lifo_t *)stk)->head;
-        ((volatile node_t *)x)->next = head;
-    } while (__sync_val_compare_and_swap(&stk->head, head, x) != head);
-}
-
-node_t *lifo_aba_pop (lifo_t *stk) {
-    node_t *head;
-    do {
-        head = ((volatile lifo_t *)stk)->head;
-        if (head == NULL)
-            return NULL;
-    } while (__sync_val_compare_and_swap(&stk->head, head, head->next) != head);
-    head->next = NULL;
-    return head;
-}
-
-node_t *node_alloc (void) {
-    node_t *node = (node_t *)nbd_malloc(sizeof(node_t));
-    memset(node, 0, sizeof(node_t));
-    return node;
-}
-
-void *worker (void *arg) {
-    int id = (int)(size_t)arg;
-    unsigned int rand_seed = (unsigned int)id + 1;
-    nbd_thread_init(id);
-
-    // Wait for all the worker threads to be ready.
-    __sync_fetch_and_add(&wait_, -1);
-    do {} while (wait_); 
-
-    int i;
-    for (i = 0; i < NUM_ITERATIONS; ++ i) {
-        int n = rand_r(&rand_seed);
-        if (n & 0x1) {
-            lifo_aba_push(stk_, node_alloc());
-        } else {
-            node_t *x = lifo_aba_pop(stk_);
-            if (x) {
-                nbd_defer_free(x);
-            }
-        }
-        rcu_update();
-    }
-
-    return NULL;
-}
-
-int main (int argc, char **argv) {
-    nbd_init();
-    //lwt_set_trace_level("m0r0");
-
-    int num_threads = 2;
-    if (argc == 2)
-    {
-        errno = 0;
-        num_threads = strtol(argv[1], NULL, 10);
-        if (errno) {
-            fprintf(stderr, "%s: Invalid argument for number of threads\n", argv[0]);
-            return -1;
-        }
-        if (num_threads <= 0) {
-            fprintf(stderr, "%s: Number of threads must be at least 1\n", argv[0]);
-            return -1;
-        }
-    }
-
-    stk_ = lifo_alloc();
-    wait_ = num_threads;
-
-    pthread_t thread[num_threads];
-    for (int i = 0; i < num_threads; ++i) {
-        int rc = pthread_create(thread + i, NULL, worker, (void *)(size_t)i);
-        if (rc != 0) { perror("pthread_create"); return rc; }
-    }
-    for (int i = 0; i < num_threads; ++i) {
-        pthread_join(thread[i], NULL);
-    }
-
-    return 0;
-}
-#endif//rcu_test