Commit d52f847a authored by Sage Weil's avatar Sage Weil
Browse files

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: default avatarSage Weil <sage@newdream.net>
parent 640ef79d

fs/ceph/msgpool.c

+27 −145
Original line number Diff line number Diff line
@@ -7,106 +7,43 @@ 


#include "msgpool.h"



/*

 * We use msg pools to preallocate memory for messages we expect to

 * receive over the wire, to avoid getting ourselves into OOM

 * conditions at unexpected times.  We take use a few different

 * strategies:

 *

 *  - for request/response type interactions, we preallocate the

 * memory needed for the response when we generate the request.

 *

 *  - for messages we can receive at any time from the MDS, we preallocate

 * a pool of messages we can re-use.

 *

 *  - for writeback, we preallocate some number of messages to use for

 * requests and their replies, so that we always make forward

 * progress.

 *

 * The msgpool behaves like a mempool_t, but keeps preallocated

 * ceph_msgs strung together on a list_head instead of using a pointer

 * vector.  This avoids vector reallocation when we adjust the number

 * of preallocated items (which happens frequently).

 */





/*

 * Allocate or release as necessary to meet our target pool size.

 */

static int __fill_msgpool(struct ceph_msgpool *pool)

static void *alloc_fn(gfp_t gfp_mask, void *arg)

{

	struct ceph_msg *msg;

	struct ceph_msgpool *pool = arg;

	struct ceph_msg *m;



	while (pool->num < pool->min) {

		dout("fill_msgpool %p %d/%d allocating\n", pool, pool->num,

		     pool->min);

		spin_unlock(&pool->lock);

		msg = ceph_msg_new(0, pool->front_len, 0, 0, NULL);

		spin_lock(&pool->lock);

		if (IS_ERR(msg))

			return PTR_ERR(msg);

		msg->pool = pool;

		list_add(&msg->list_head, &pool->msgs);

		pool->num++;

	m = ceph_msg_new(0, pool->front_len, 0, 0, NULL);

	if (IS_ERR(m))

		return NULL;

	return m;

}

	while (pool->num > pool->min) {

		msg = list_first_entry(&pool->msgs, struct ceph_msg, list_head);

		dout("fill_msgpool %p %d/%d releasing %p\n", pool, pool->num,

		     pool->min, msg);

		list_del_init(&msg->list_head);

		pool->num--;

		ceph_msg_kfree(msg);

	}

	return 0;



static void free_fn(void *element, void *arg)

{

	ceph_msg_put(element);

}



int ceph_msgpool_init(struct ceph_msgpool *pool,

		      int front_len, int min, bool blocking)

		      int front_len, int size, bool blocking)

{

	int ret;



	dout("msgpool_init %p front_len %d min %d\n", pool, front_len, min);

	spin_lock_init(&pool->lock);

	pool->front_len = front_len;

	INIT_LIST_HEAD(&pool->msgs);

	pool->num = 0;

	pool->min = min;

	pool->blocking = blocking;

	init_waitqueue_head(&pool->wait);



	spin_lock(&pool->lock);

	ret = __fill_msgpool(pool);

	spin_unlock(&pool->lock);

	return ret;

	pool->pool = mempool_create(size, alloc_fn, free_fn, pool);

	if (!pool->pool)

		return -ENOMEM;

	return 0;

}



void ceph_msgpool_destroy(struct ceph_msgpool *pool)

{

	dout("msgpool_destroy %p\n", pool);

	spin_lock(&pool->lock);

	pool->min = 0;

	__fill_msgpool(pool);

	spin_unlock(&pool->lock);

}



int ceph_msgpool_resv(struct ceph_msgpool *pool, int delta)

{

	int ret;



	spin_lock(&pool->lock);

	dout("msgpool_resv %p delta %d\n", pool, delta);

	pool->min += delta;

	ret = __fill_msgpool(pool);

	spin_unlock(&pool->lock);

	return ret;

	mempool_destroy(pool->pool);

}



struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool, int front_len)

struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool,

				  int front_len)

{

	wait_queue_t wait;

	if (front_len > pool->front_len) {

		struct ceph_msg *msg;



	if (front_len && front_len > pool->front_len) {

		pr_err("msgpool_get pool %p need front %d, pool size is %d\n",

		       pool, front_len, pool->front_len);

		WARN_ON(1);
@@ -115,72 +52,17 @@ struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool, int front_len) 
		msg = ceph_msg_new(0, front_len, 0, 0, NULL);

		if (!IS_ERR(msg))

			return msg;

		return NULL;

	}



	if (!front_len)

		front_len = pool->front_len;



	if (pool->blocking) {

		/* mempool_t behavior; first try to alloc */

		msg = ceph_msg_new(0, front_len, 0, 0, NULL);

		if (!IS_ERR(msg))

			return msg;

	}



	while (1) {

		spin_lock(&pool->lock);

		if (likely(pool->num)) {

			msg = list_entry(pool->msgs.next, struct ceph_msg,

					 list_head);

			list_del_init(&msg->list_head);

			pool->num--;

			dout("msgpool_get %p got %p, now %d/%d\n", pool, msg,

			     pool->num, pool->min);

			spin_unlock(&pool->lock);

			return msg;

		}

		pr_err("msgpool_get %p now %d/%d, %s\n", pool, pool->num,

		       pool->min, pool->blocking ? "waiting" : "may fail");

		spin_unlock(&pool->lock);



		if (!pool->blocking) {

			WARN_ON(1);



			/* maybe we can allocate it now? */

			msg = ceph_msg_new(0, front_len, 0, 0, NULL);

			if (!IS_ERR(msg))

				return msg;



			pr_err("msgpool_get %p empty + alloc failed\n", pool);

			return ERR_PTR(-ENOMEM);

		}



		init_wait(&wait);

		prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);

		schedule();

		finish_wait(&pool->wait, &wait);

	}

	return mempool_alloc(pool->pool, GFP_NOFS);

}



void ceph_msgpool_put(struct ceph_msgpool *pool, struct ceph_msg *msg)

{

	spin_lock(&pool->lock);

	if (pool->num < pool->min) {

	/* reset msg front_len; user may have changed it */

	msg->front.iov_len = pool->front_len;

	msg->hdr.front_len = cpu_to_le32(pool->front_len);



		kref_init(&msg->kref);  /* retake a single ref */

		list_add(&msg->list_head, &pool->msgs);

		pool->num++;

		dout("msgpool_put %p reclaim %p, now %d/%d\n", pool, msg,

		     pool->num, pool->min);

		spin_unlock(&pool->lock);

		wake_up(&pool->wait);

	} else {

		dout("msgpool_put %p drop %p, at %d/%d\n", pool, msg,

		     pool->num, pool->min);

		spin_unlock(&pool->lock);

		ceph_msg_kfree(msg);

	}

	kref_init(&msg->kref);  /* retake single ref */

}

fs/ceph/msgpool.h

+2 −6
Original line number Diff line number Diff line 
#ifndef _FS_CEPH_MSGPOOL

#define _FS_CEPH_MSGPOOL



#include <linux/mempool.h>

#include "messenger.h"



/*
@@ -8,18 +9,13 @@ 
 * avoid unexpected OOM conditions.

 */

struct ceph_msgpool {

	spinlock_t lock;

	mempool_t *pool;

	int front_len;          /* preallocated payload size */

	struct list_head msgs;  /* msgs in the pool; each has 1 ref */

	int num, min;           /* cur, min # msgs in the pool */

	bool blocking;

	wait_queue_head_t wait;

};



extern int ceph_msgpool_init(struct ceph_msgpool *pool,

			     int front_len, int size, bool blocking);

extern void ceph_msgpool_destroy(struct ceph_msgpool *pool);

extern int ceph_msgpool_resv(struct ceph_msgpool *, int delta);

extern struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *,

					 int front_len);

extern void ceph_msgpool_put(struct ceph_msgpool *, struct ceph_msg *);