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Subject[DLM] Use workqueues for dlm lowcomms [23/54]
From
Date
>From 8b3c1aacbf337ec3c9a354c9ad9a86f4d31e72fc Mon Sep 17 00:00:00 2001
From: Patrick Caulfield <pcaulfie@redhat.com>
Date: Mon, 15 Jan 2007 14:33:34 +0000
Subject: [PATCH] [DLM] Use workqueues for dlm lowcomms
This patch converts the DLM TCP lowcomms to use workqueues rather than using its
own daemon functions. Simultaneously removing a lot of code and making it more
scalable on multi-processor machines.

Signed-Off-By: Patrick Caulfield <pcaulfie@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/dlm/lowcomms-sctp.c b/fs/dlm/lowcomms-sctp.c
index 5aeadad..dc83a9d 100644
--- a/fs/dlm/lowcomms-sctp.c
+++ b/fs/dlm/lowcomms-sctp.c
@@ -72,6 +72,8 @@ struct nodeinfo {
struct list_head writequeue; /* outgoing writequeue_entries */
spinlock_t writequeue_lock;
int nodeid;
+ struct work_struct swork; /* Send workqueue */
+ struct work_struct lwork; /* Locking workqueue */
};

static DEFINE_IDR(nodeinfo_idr);
@@ -96,6 +98,7 @@ struct connection {
atomic_t waiting_requests;
struct cbuf cb;
int eagain_flag;
+ struct work_struct work; /* Send workqueue */
};

/* An entry waiting to be sent */
@@ -137,19 +140,23 @@ static void cbuf_eat(struct cbuf *cb, int n)
static LIST_HEAD(write_nodes);
static DEFINE_SPINLOCK(write_nodes_lock);

+
/* Maximum number of incoming messages to process before
* doing a schedule()
*/
#define MAX_RX_MSG_COUNT 25

-/* Manage daemons */
-static struct task_struct *recv_task;
-static struct task_struct *send_task;
-static DECLARE_WAIT_QUEUE_HEAD(lowcomms_recv_wait);
+/* Work queues */
+static struct workqueue_struct *recv_workqueue;
+static struct workqueue_struct *send_workqueue;
+static struct workqueue_struct *lock_workqueue;

/* The SCTP connection */
static struct connection sctp_con;

+static void process_send_sockets(struct work_struct *work);
+static void process_recv_sockets(struct work_struct *work);
+static void process_lock_request(struct work_struct *work);

static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
{
@@ -222,6 +229,8 @@ static struct nodeinfo *nodeid2nodeinfo(int nodeid, gfp_t alloc)
spin_lock_init(&ni->lock);
INIT_LIST_HEAD(&ni->writequeue);
spin_lock_init(&ni->writequeue_lock);
+ INIT_WORK(&ni->lwork, process_lock_request);
+ INIT_WORK(&ni->swork, process_send_sockets);
ni->nodeid = nodeid;

if (nodeid > max_nodeid)
@@ -249,11 +258,8 @@ static struct nodeinfo *assoc2nodeinfo(sctp_assoc_t assoc)
/* Data or notification available on socket */
static void lowcomms_data_ready(struct sock *sk, int count_unused)
{
- atomic_inc(&sctp_con.waiting_requests);
if (test_and_set_bit(CF_READ_PENDING, &sctp_con.flags))
- return;
-
- wake_up_interruptible(&lowcomms_recv_wait);
+ queue_work(recv_workqueue, &sctp_con.work);
}


@@ -361,10 +367,10 @@ static void init_failed(void)
spin_lock_bh(&write_nodes_lock);
list_add_tail(&ni->write_list, &write_nodes);
spin_unlock_bh(&write_nodes_lock);
+ queue_work(send_workqueue, &ni->swork);
}
}
}
- wake_up_process(send_task);
}

/* Something happened to an association */
@@ -446,8 +452,8 @@ static void process_sctp_notification(struct msghdr *msg, char *buf)
spin_lock_bh(&write_nodes_lock);
list_add_tail(&ni->write_list, &write_nodes);
spin_unlock_bh(&write_nodes_lock);
+ queue_work(send_workqueue, &ni->swork);
}
- wake_up_process(send_task);
}
break;

@@ -580,8 +586,8 @@ static int receive_from_sock(void)
spin_lock_bh(&write_nodes_lock);
list_add_tail(&ni->write_list, &write_nodes);
spin_unlock_bh(&write_nodes_lock);
+ queue_work(send_workqueue, &ni->swork);
}
- wake_up_process(send_task);
}
}

@@ -590,6 +596,7 @@ static int receive_from_sock(void)
return 0;

cbuf_add(&sctp_con.cb, ret);
+ // PJC: TODO: Add to node's workqueue....can we ??
ret = dlm_process_incoming_buffer(cpu_to_le32(sinfo->sinfo_ppid),
page_address(sctp_con.rx_page),
sctp_con.cb.base, sctp_con.cb.len,
@@ -820,7 +827,8 @@ void dlm_lowcomms_commit_buffer(void *arg)
spin_lock_bh(&write_nodes_lock);
list_add_tail(&ni->write_list, &write_nodes);
spin_unlock_bh(&write_nodes_lock);
- wake_up_process(send_task);
+
+ queue_work(send_workqueue, &ni->swork);
}
return;

@@ -1088,101 +1096,75 @@ int dlm_lowcomms_close(int nodeid)
return 0;
}

-static int write_list_empty(void)
+// PJC: The work queue function for receiving.
+static void process_recv_sockets(struct work_struct *work)
{
- int status;
+ if (test_and_clear_bit(CF_READ_PENDING, &sctp_con.flags)) {
+ int ret;
+ int count = 0;

- spin_lock_bh(&write_nodes_lock);
- status = list_empty(&write_nodes);
- spin_unlock_bh(&write_nodes_lock);
+ do {
+ ret = receive_from_sock();

- return status;
+ /* Don't starve out everyone else */
+ if (++count >= MAX_RX_MSG_COUNT) {
+ cond_resched();
+ count = 0;
+ }
+ } while (!kthread_should_stop() && ret >=0);
+ }
+ cond_resched();
}

-static int dlm_recvd(void *data)
+// PJC: the work queue function for sending
+static void process_send_sockets(struct work_struct *work)
{
- DECLARE_WAITQUEUE(wait, current);
-
- while (!kthread_should_stop()) {
- int count = 0;
-
- set_current_state(TASK_INTERRUPTIBLE);
- add_wait_queue(&lowcomms_recv_wait, &wait);
- if (!test_bit(CF_READ_PENDING, &sctp_con.flags))
- schedule();
- remove_wait_queue(&lowcomms_recv_wait, &wait);
- set_current_state(TASK_RUNNING);
-
- if (test_and_clear_bit(CF_READ_PENDING, &sctp_con.flags)) {
- int ret;
-
- do {
- ret = receive_from_sock();
-
- /* Don't starve out everyone else */
- if (++count >= MAX_RX_MSG_COUNT) {
- cond_resched();
- count = 0;
- }
- } while (!kthread_should_stop() && ret >=0);
- }
- cond_resched();
+ if (sctp_con.eagain_flag) {
+ sctp_con.eagain_flag = 0;
+ refill_write_queue();
}
-
- return 0;
+ process_output_queue();
}

-static int dlm_sendd(void *data)
+// PJC: Process lock requests from a particular node.
+// TODO: can we optimise this out on UP ??
+static void process_lock_request(struct work_struct *work)
{
- DECLARE_WAITQUEUE(wait, current);
-
- add_wait_queue(sctp_con.sock->sk->sk_sleep, &wait);
-
- while (!kthread_should_stop()) {
- set_current_state(TASK_INTERRUPTIBLE);
- if (write_list_empty())
- schedule();
- set_current_state(TASK_RUNNING);
-
- if (sctp_con.eagain_flag) {
- sctp_con.eagain_flag = 0;
- refill_write_queue();
- }
- process_output_queue();
- }
-
- remove_wait_queue(sctp_con.sock->sk->sk_sleep, &wait);
-
- return 0;
}

static void daemons_stop(void)
{
- kthread_stop(recv_task);
- kthread_stop(send_task);
+ destroy_workqueue(recv_workqueue);
+ destroy_workqueue(send_workqueue);
+ destroy_workqueue(lock_workqueue);
}

static int daemons_start(void)
{
- struct task_struct *p;
int error;
+ recv_workqueue = create_workqueue("dlm_recv");
+ error = IS_ERR(recv_workqueue);
+ if (error) {
+ log_print("can't start dlm_recv %d", error);
+ return error;
+ }

- p = kthread_run(dlm_recvd, NULL, "dlm_recvd");
- error = IS_ERR(p);
+ send_workqueue = create_singlethread_workqueue("dlm_send");
+ error = IS_ERR(send_workqueue);
if (error) {
- log_print("can't start dlm_recvd %d", error);
+ log_print("can't start dlm_send %d", error);
+ destroy_workqueue(recv_workqueue);
return error;
}
- recv_task = p;

- p = kthread_run(dlm_sendd, NULL, "dlm_sendd");
- error = IS_ERR(p);
+ lock_workqueue = create_workqueue("dlm_rlock");
+ error = IS_ERR(lock_workqueue);
if (error) {
- log_print("can't start dlm_sendd %d", error);
- kthread_stop(recv_task);
+ log_print("can't start dlm_rlock %d", error);
+ destroy_workqueue(send_workqueue);
+ destroy_workqueue(recv_workqueue);
return error;
}
- send_task = p;

return 0;
}
@@ -1194,6 +1176,8 @@ int dlm_lowcomms_start(void)
{
int error;

+ INIT_WORK(&sctp_con.work, process_recv_sockets);
+
error = init_sock();
if (error)
goto fail_sock;
@@ -1224,4 +1208,3 @@ void dlm_lowcomms_stop(void)
for (i = 0; i < dlm_local_count; i++)
kfree(dlm_local_addr[i]);
}
-
diff --git a/fs/dlm/lowcomms-tcp.c b/fs/dlm/lowcomms-tcp.c
index b4fb578..86e5f81 100644
--- a/fs/dlm/lowcomms-tcp.c
+++ b/fs/dlm/lowcomms-tcp.c
@@ -115,6 +115,8 @@ struct connection {
atomic_t waiting_requests;
#define MAX_CONNECT_RETRIES 3
struct connection *othercon;
+ struct work_struct rwork; /* Receive workqueue */
+ struct work_struct swork; /* Send workqueue */
};
#define sock2con(x) ((struct connection *)(x)->sk_user_data)

@@ -131,14 +133,9 @@ struct writequeue_entry {

static struct sockaddr_storage dlm_local_addr;

-/* Manage daemons */
-static struct task_struct *recv_task;
-static struct task_struct *send_task;
-
-static wait_queue_t lowcomms_send_waitq_head;
-static DECLARE_WAIT_QUEUE_HEAD(lowcomms_send_waitq);
-static wait_queue_t lowcomms_recv_waitq_head;
-static DECLARE_WAIT_QUEUE_HEAD(lowcomms_recv_waitq);
+/* Work queues */
+static struct workqueue_struct *recv_workqueue;
+static struct workqueue_struct *send_workqueue;

/* An array of pointers to connections, indexed by NODEID */
static struct connection **connections;
@@ -146,17 +143,8 @@ static DECLARE_MUTEX(connections_lock);
static struct kmem_cache *con_cache;
static int conn_array_size;

-/* List of sockets that have reads pending */
-static LIST_HEAD(read_sockets);
-static DEFINE_SPINLOCK(read_sockets_lock);
-
-/* List of sockets which have writes pending */
-static LIST_HEAD(write_sockets);
-static DEFINE_SPINLOCK(write_sockets_lock);
-
-/* List of sockets which have connects pending */
-static LIST_HEAD(state_sockets);
-static DEFINE_SPINLOCK(state_sockets_lock);
+static void process_recv_sockets(struct work_struct *work);
+static void process_send_sockets(struct work_struct *work);

static struct connection *nodeid2con(int nodeid, gfp_t allocation)
{
@@ -189,6 +177,8 @@ static struct connection *nodeid2con(int nodeid, gfp_t allocation)
init_rwsem(&con->sock_sem);
INIT_LIST_HEAD(&con->writequeue);
spin_lock_init(&con->writequeue_lock);
+ INIT_WORK(&con->swork, process_send_sockets);
+ INIT_WORK(&con->rwork, process_recv_sockets);

connections[nodeid] = con;
}
@@ -203,41 +193,22 @@ static void lowcomms_data_ready(struct sock *sk, int count_unused)
{
struct connection *con = sock2con(sk);

- atomic_inc(&con->waiting_requests);
- if (test_and_set_bit(CF_READ_PENDING, &con->flags))
- return;
-
- spin_lock_bh(&read_sockets_lock);
- list_add_tail(&con->read_list, &read_sockets);
- spin_unlock_bh(&read_sockets_lock);
-
- wake_up_interruptible(&lowcomms_recv_waitq);
+ if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
+ queue_work(recv_workqueue, &con->rwork);
}

static void lowcomms_write_space(struct sock *sk)
{
struct connection *con = sock2con(sk);

- if (test_and_set_bit(CF_WRITE_PENDING, &con->flags))
- return;
-
- spin_lock_bh(&write_sockets_lock);
- list_add_tail(&con->write_list, &write_sockets);
- spin_unlock_bh(&write_sockets_lock);
-
- wake_up_interruptible(&lowcomms_send_waitq);
+ if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
+ queue_work(send_workqueue, &con->swork);
}

static inline void lowcomms_connect_sock(struct connection *con)
{
- if (test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
- return;
-
- spin_lock_bh(&state_sockets_lock);
- list_add_tail(&con->state_list, &state_sockets);
- spin_unlock_bh(&state_sockets_lock);
-
- wake_up_interruptible(&lowcomms_send_waitq);
+ if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
+ queue_work(send_workqueue, &con->swork);
}

static void lowcomms_state_change(struct sock *sk)
@@ -388,7 +359,8 @@ out:
return 0;

out_resched:
- lowcomms_data_ready(con->sock->sk, 0);
+ if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
+ queue_work(recv_workqueue, &con->rwork);
up_read(&con->sock_sem);
cond_resched();
return 0;
@@ -477,6 +449,8 @@ static int accept_from_sock(struct connection *con)
othercon->nodeid = nodeid;
othercon->rx_action = receive_from_sock;
init_rwsem(&othercon->sock_sem);
+ INIT_WORK(&othercon->swork, process_send_sockets);
+ INIT_WORK(&othercon->rwork, process_recv_sockets);
set_bit(CF_IS_OTHERCON, &othercon->flags);
newcon->othercon = othercon;
}
@@ -498,7 +472,8 @@ static int accept_from_sock(struct connection *con)
* beween processing the accept adding the socket
* to the read_sockets list
*/
- lowcomms_data_ready(newsock->sk, 0);
+ if (!test_and_set_bit(CF_READ_PENDING, &newcon->flags))
+ queue_work(recv_workqueue, &newcon->rwork);
up_read(&con->sock_sem);

return 0;
@@ -757,12 +732,8 @@ void dlm_lowcomms_commit_buffer(void *mh)
kunmap(e->page);
spin_unlock(&con->writequeue_lock);

- if (test_and_set_bit(CF_WRITE_PENDING, &con->flags) == 0) {
- spin_lock_bh(&write_sockets_lock);
- list_add_tail(&con->write_list, &write_sockets);
- spin_unlock_bh(&write_sockets_lock);
-
- wake_up_interruptible(&lowcomms_send_waitq);
+ if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
+ queue_work(send_workqueue, &con->swork);
}
return;

@@ -803,6 +774,7 @@ static void send_to_sock(struct connection *con)
offset = e->offset;
BUG_ON(len == 0 && e->users == 0);
spin_unlock(&con->writequeue_lock);
+ kmap(e->page);

ret = 0;
if (len) {
@@ -884,85 +856,29 @@ out:
}

/* Look for activity on active sockets */
-static void process_sockets(void)
+static void process_recv_sockets(struct work_struct *work)
{
- struct list_head *list;
- struct list_head *temp;
- int count = 0;
-
- spin_lock_bh(&read_sockets_lock);
- list_for_each_safe(list, temp, &read_sockets) {
-
- struct connection *con =
- list_entry(list, struct connection, read_list);
- list_del(&con->read_list);
- clear_bit(CF_READ_PENDING, &con->flags);
-
- spin_unlock_bh(&read_sockets_lock);
+ struct connection *con = container_of(work, struct connection, rwork);
+ int err;

- /* This can reach zero if we are processing requests
- * as they come in.
- */
- if (atomic_read(&con->waiting_requests) == 0) {
- spin_lock_bh(&read_sockets_lock);
- continue;
- }
-
- do {
- con->rx_action(con);
-
- /* Don't starve out everyone else */
- if (++count >= MAX_RX_MSG_COUNT) {
- cond_resched();
- count = 0;
- }
-
- } while (!atomic_dec_and_test(&con->waiting_requests) &&
- !kthread_should_stop());
-
- spin_lock_bh(&read_sockets_lock);
- }
- spin_unlock_bh(&read_sockets_lock);
+ clear_bit(CF_READ_PENDING, &con->flags);
+ do {
+ err = con->rx_action(con);
+ } while (!err);
}

-/* Try to send any messages that are pending
- */
-static void process_output_queue(void)
-{
- struct list_head *list;
- struct list_head *temp;
-
- spin_lock_bh(&write_sockets_lock);
- list_for_each_safe(list, temp, &write_sockets) {
- struct connection *con =
- list_entry(list, struct connection, write_list);
- clear_bit(CF_WRITE_PENDING, &con->flags);
- list_del(&con->write_list);
-
- spin_unlock_bh(&write_sockets_lock);
- send_to_sock(con);
- spin_lock_bh(&write_sockets_lock);
- }
- spin_unlock_bh(&write_sockets_lock);
-}

-static void process_state_queue(void)
+static void process_send_sockets(struct work_struct *work)
{
- struct list_head *list;
- struct list_head *temp;
-
- spin_lock_bh(&state_sockets_lock);
- list_for_each_safe(list, temp, &state_sockets) {
- struct connection *con =
- list_entry(list, struct connection, state_list);
- list_del(&con->state_list);
- clear_bit(CF_CONNECT_PENDING, &con->flags);
- spin_unlock_bh(&state_sockets_lock);
+ struct connection *con = container_of(work, struct connection, swork);

+ if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
connect_to_sock(con);
- spin_lock_bh(&state_sockets_lock);
}
- spin_unlock_bh(&state_sockets_lock);
+
+ if (test_and_clear_bit(CF_WRITE_PENDING, &con->flags)) {
+ send_to_sock(con);
+ }
}


@@ -979,97 +895,29 @@ static void clean_writequeues(void)
}
}

-static int read_list_empty(void)
-{
- int status;
-
- spin_lock_bh(&read_sockets_lock);
- status = list_empty(&read_sockets);
- spin_unlock_bh(&read_sockets_lock);
-
- return status;
-}
-
-/* DLM Transport comms receive daemon */
-static int dlm_recvd(void *data)
+static void work_stop(void)
{
- init_waitqueue_entry(&lowcomms_recv_waitq_head, current);
- add_wait_queue(&lowcomms_recv_waitq, &lowcomms_recv_waitq_head);
-
- while (!kthread_should_stop()) {
- set_current_state(TASK_INTERRUPTIBLE);
- if (read_list_empty())
- schedule();
- set_current_state(TASK_RUNNING);
-
- process_sockets();
- }
-
- return 0;
+ destroy_workqueue(recv_workqueue);
+ destroy_workqueue(send_workqueue);
}

-static int write_and_state_lists_empty(void)
+static int work_start(void)
{
- int status;
-
- spin_lock_bh(&write_sockets_lock);
- status = list_empty(&write_sockets);
- spin_unlock_bh(&write_sockets_lock);
-
- spin_lock_bh(&state_sockets_lock);
- if (list_empty(&state_sockets) == 0)
- status = 0;
- spin_unlock_bh(&state_sockets_lock);
-
- return status;
-}
-
-/* DLM Transport send daemon */
-static int dlm_sendd(void *data)
-{
- init_waitqueue_entry(&lowcomms_send_waitq_head, current);
- add_wait_queue(&lowcomms_send_waitq, &lowcomms_send_waitq_head);
-
- while (!kthread_should_stop()) {
- set_current_state(TASK_INTERRUPTIBLE);
- if (write_and_state_lists_empty())
- schedule();
- set_current_state(TASK_RUNNING);
-
- process_state_queue();
- process_output_queue();
- }
-
- return 0;
-}
-
-static void daemons_stop(void)
-{
- kthread_stop(recv_task);
- kthread_stop(send_task);
-}
-
-static int daemons_start(void)
-{
- struct task_struct *p;
int error;
-
- p = kthread_run(dlm_recvd, NULL, "dlm_recvd");
- error = IS_ERR(p);
+ recv_workqueue = create_workqueue("dlm_recv");
+ error = IS_ERR(recv_workqueue);
if (error) {
- log_print("can't start dlm_recvd %d", error);
+ log_print("can't start dlm_recv %d", error);
return error;
}
- recv_task = p;

- p = kthread_run(dlm_sendd, NULL, "dlm_sendd");
- error = IS_ERR(p);
+ send_workqueue = create_singlethread_workqueue("dlm_send");
+ error = IS_ERR(send_workqueue);
if (error) {
- log_print("can't start dlm_sendd %d", error);
- kthread_stop(recv_task);
+ log_print("can't start dlm_send %d", error);
+ destroy_workqueue(recv_workqueue);
return error;
}
- send_task = p;

return 0;
}
@@ -1086,7 +934,7 @@ void dlm_lowcomms_stop(void)
connections[i]->flags |= 0xFF;
}

- daemons_stop();
+ work_stop();
clean_writequeues();

for (i = 0; i < conn_array_size; i++) {
@@ -1138,7 +986,7 @@ int dlm_lowcomms_start(void)
if (error)
goto fail_unlisten;

- error = daemons_start();
+ error = work_start();
if (error)
goto fail_unlisten;

--
1.4.4.2


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