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ceph: rewrite msgpool using mempool_t
Since we don't need to maintain large pools of messages, we can just use the standard mempool_t. We maintain a msgpool 'wrapper' because we need the mempool_t* in the alloc function, and mempool gives us only pool_data. Signed-off-by: Sage Weil <sage@newdream.net>
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Sage Weil
parent
640ef79d27
commit
d52f847a84
@ -7,106 +7,43 @@
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#include "msgpool.h"
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/*
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* We use msg pools to preallocate memory for messages we expect to
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* receive over the wire, to avoid getting ourselves into OOM
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* conditions at unexpected times. We take use a few different
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* strategies:
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*
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* - for request/response type interactions, we preallocate the
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* memory needed for the response when we generate the request.
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*
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* - for messages we can receive at any time from the MDS, we preallocate
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* a pool of messages we can re-use.
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*
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* - for writeback, we preallocate some number of messages to use for
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* requests and their replies, so that we always make forward
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* progress.
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*
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* The msgpool behaves like a mempool_t, but keeps preallocated
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* ceph_msgs strung together on a list_head instead of using a pointer
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* vector. This avoids vector reallocation when we adjust the number
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* of preallocated items (which happens frequently).
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*/
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/*
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* Allocate or release as necessary to meet our target pool size.
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*/
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static int __fill_msgpool(struct ceph_msgpool *pool)
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static void *alloc_fn(gfp_t gfp_mask, void *arg)
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{
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struct ceph_msg *msg;
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struct ceph_msgpool *pool = arg;
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struct ceph_msg *m;
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while (pool->num < pool->min) {
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dout("fill_msgpool %p %d/%d allocating\n", pool, pool->num,
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pool->min);
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spin_unlock(&pool->lock);
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msg = ceph_msg_new(0, pool->front_len, 0, 0, NULL);
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spin_lock(&pool->lock);
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if (IS_ERR(msg))
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return PTR_ERR(msg);
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msg->pool = pool;
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list_add(&msg->list_head, &pool->msgs);
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pool->num++;
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}
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while (pool->num > pool->min) {
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msg = list_first_entry(&pool->msgs, struct ceph_msg, list_head);
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dout("fill_msgpool %p %d/%d releasing %p\n", pool, pool->num,
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pool->min, msg);
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list_del_init(&msg->list_head);
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pool->num--;
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ceph_msg_kfree(msg);
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}
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return 0;
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m = ceph_msg_new(0, pool->front_len, 0, 0, NULL);
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if (IS_ERR(m))
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return NULL;
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return m;
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}
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static void free_fn(void *element, void *arg)
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{
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ceph_msg_put(element);
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}
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int ceph_msgpool_init(struct ceph_msgpool *pool,
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int front_len, int min, bool blocking)
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int front_len, int size, bool blocking)
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{
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int ret;
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dout("msgpool_init %p front_len %d min %d\n", pool, front_len, min);
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spin_lock_init(&pool->lock);
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pool->front_len = front_len;
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INIT_LIST_HEAD(&pool->msgs);
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pool->num = 0;
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pool->min = min;
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pool->blocking = blocking;
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init_waitqueue_head(&pool->wait);
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spin_lock(&pool->lock);
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ret = __fill_msgpool(pool);
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spin_unlock(&pool->lock);
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return ret;
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pool->pool = mempool_create(size, alloc_fn, free_fn, pool);
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if (!pool->pool)
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return -ENOMEM;
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return 0;
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}
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void ceph_msgpool_destroy(struct ceph_msgpool *pool)
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{
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dout("msgpool_destroy %p\n", pool);
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spin_lock(&pool->lock);
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pool->min = 0;
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__fill_msgpool(pool);
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spin_unlock(&pool->lock);
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mempool_destroy(pool->pool);
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}
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int ceph_msgpool_resv(struct ceph_msgpool *pool, int delta)
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struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool,
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int front_len)
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{
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int ret;
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if (front_len > pool->front_len) {
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struct ceph_msg *msg;
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spin_lock(&pool->lock);
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dout("msgpool_resv %p delta %d\n", pool, delta);
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pool->min += delta;
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ret = __fill_msgpool(pool);
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spin_unlock(&pool->lock);
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return ret;
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}
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struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool, int front_len)
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{
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wait_queue_t wait;
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struct ceph_msg *msg;
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if (front_len && front_len > pool->front_len) {
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pr_err("msgpool_get pool %p need front %d, pool size is %d\n",
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pool, front_len, pool->front_len);
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WARN_ON(1);
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@ -115,72 +52,17 @@ struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool, int front_len)
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msg = ceph_msg_new(0, front_len, 0, 0, NULL);
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if (!IS_ERR(msg))
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return msg;
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return NULL;
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}
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if (!front_len)
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front_len = pool->front_len;
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if (pool->blocking) {
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/* mempool_t behavior; first try to alloc */
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msg = ceph_msg_new(0, front_len, 0, 0, NULL);
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if (!IS_ERR(msg))
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return msg;
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}
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while (1) {
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spin_lock(&pool->lock);
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if (likely(pool->num)) {
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msg = list_entry(pool->msgs.next, struct ceph_msg,
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list_head);
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list_del_init(&msg->list_head);
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pool->num--;
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dout("msgpool_get %p got %p, now %d/%d\n", pool, msg,
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pool->num, pool->min);
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spin_unlock(&pool->lock);
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return msg;
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}
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pr_err("msgpool_get %p now %d/%d, %s\n", pool, pool->num,
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pool->min, pool->blocking ? "waiting" : "may fail");
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spin_unlock(&pool->lock);
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if (!pool->blocking) {
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WARN_ON(1);
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/* maybe we can allocate it now? */
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msg = ceph_msg_new(0, front_len, 0, 0, NULL);
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if (!IS_ERR(msg))
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return msg;
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pr_err("msgpool_get %p empty + alloc failed\n", pool);
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return ERR_PTR(-ENOMEM);
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}
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init_wait(&wait);
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prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
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schedule();
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finish_wait(&pool->wait, &wait);
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}
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return mempool_alloc(pool->pool, GFP_NOFS);
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}
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void ceph_msgpool_put(struct ceph_msgpool *pool, struct ceph_msg *msg)
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{
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spin_lock(&pool->lock);
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if (pool->num < pool->min) {
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/* reset msg front_len; user may have changed it */
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msg->front.iov_len = pool->front_len;
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msg->hdr.front_len = cpu_to_le32(pool->front_len);
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/* reset msg front_len; user may have changed it */
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msg->front.iov_len = pool->front_len;
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msg->hdr.front_len = cpu_to_le32(pool->front_len);
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kref_init(&msg->kref); /* retake a single ref */
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list_add(&msg->list_head, &pool->msgs);
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pool->num++;
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dout("msgpool_put %p reclaim %p, now %d/%d\n", pool, msg,
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pool->num, pool->min);
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spin_unlock(&pool->lock);
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wake_up(&pool->wait);
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} else {
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dout("msgpool_put %p drop %p, at %d/%d\n", pool, msg,
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pool->num, pool->min);
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spin_unlock(&pool->lock);
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ceph_msg_kfree(msg);
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}
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kref_init(&msg->kref); /* retake single ref */
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}
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@ -1,6 +1,7 @@
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#ifndef _FS_CEPH_MSGPOOL
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#define _FS_CEPH_MSGPOOL
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#include <linux/mempool.h>
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#include "messenger.h"
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/*
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@ -8,18 +9,13 @@
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* avoid unexpected OOM conditions.
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*/
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struct ceph_msgpool {
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spinlock_t lock;
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mempool_t *pool;
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int front_len; /* preallocated payload size */
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struct list_head msgs; /* msgs in the pool; each has 1 ref */
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int num, min; /* cur, min # msgs in the pool */
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bool blocking;
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wait_queue_head_t wait;
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};
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extern int ceph_msgpool_init(struct ceph_msgpool *pool,
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int front_len, int size, bool blocking);
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extern void ceph_msgpool_destroy(struct ceph_msgpool *pool);
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extern int ceph_msgpool_resv(struct ceph_msgpool *, int delta);
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extern struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *,
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int front_len);
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extern void ceph_msgpool_put(struct ceph_msgpool *, struct ceph_msg *);
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