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SUNRPC: Add basic load balancing to the transport switch 

For now, just count the queue length. It is less accurate than counting
number of bytes queued, but easier to implement.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2017-04-28 10:52:42 -04:00 committed by Trond Myklebust
parent 44942b4e45
commit 21f0ffaff5
4 changed files with 59 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/sunrpc/xprt.h
View File

@ -238,6 +238,7 @@ struct rpc_xprt {
/*
* Send stuff
*/
atomic_long_t queuelen;
spinlock_t transport_lock; /* lock transport info */
spinlock_t reserve_lock; /* lock slot table */
spinlock_t queue_lock; /* send/receive queue lock */

2
include/linux/sunrpc/xprtmultipath.h
View File

@ -15,6 +15,8 @@ struct rpc_xprt_switch {
struct kref xps_kref;
unsigned int xps_nxprts;
unsigned int xps_nactive;
atomic_long_t xps_queuelen;
struct list_head xps_xprt_list;
struct net * xps_net;

40
net/sunrpc/clnt.c
View File

@ -968,13 +968,47 @@ out:
}
EXPORT_SYMBOL_GPL(rpc_bind_new_program);
static struct rpc_xprt *
rpc_task_get_xprt(struct rpc_clnt *clnt)
{
struct rpc_xprt_switch *xps;
struct rpc_xprt *xprt= xprt_iter_get_next(&clnt->cl_xpi);
if (!xprt)
return NULL;
rcu_read_lock();
xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
atomic_long_inc(&xps->xps_queuelen);
rcu_read_unlock();
atomic_long_inc(&xprt->queuelen);
return xprt;
}
static void
rpc_task_release_xprt(struct rpc_clnt *clnt, struct rpc_xprt *xprt)
{
struct rpc_xprt_switch *xps;
atomic_long_dec(&xprt->queuelen);
rcu_read_lock();
xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
atomic_long_dec(&xps->xps_queuelen);
rcu_read_unlock();
xprt_put(xprt);
}
void rpc_task_release_transport(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
if (xprt) {
task->tk_xprt = NULL;
xprt_put(xprt);
if (task->tk_client)
rpc_task_release_xprt(task->tk_client, xprt);
else
xprt_put(xprt);
}
}
EXPORT_SYMBOL_GPL(rpc_task_release_transport);
@ -983,6 +1017,7 @@ void rpc_task_release_client(struct rpc_task *task)
{
struct rpc_clnt *clnt = task->tk_client;
rpc_task_release_transport(task);
if (clnt != NULL) {
/* Remove from client task list */
spin_lock(&clnt->cl_lock);
@ -992,14 +1027,13 @@ void rpc_task_release_client(struct rpc_task *task)
rpc_release_client(clnt);
}
rpc_task_release_transport(task);
}
static
void rpc_task_set_transport(struct rpc_task *task, struct rpc_clnt *clnt)
{
if (!task->tk_xprt)
task->tk_xprt = xprt_iter_get_next(&clnt->cl_xpi);
task->tk_xprt = rpc_task_get_xprt(clnt);
}
static

20
net/sunrpc/xprtmultipath.c
View File

@ -36,6 +36,7 @@ static void xprt_switch_add_xprt_locked(struct rpc_xprt_switch *xps,
if (xps->xps_nxprts == 0)
xps->xps_net = xprt->xprt_net;
xps->xps_nxprts++;
xps->xps_nactive++;
}
/**
@ -62,6 +63,7 @@ static void xprt_switch_remove_xprt_locked(struct rpc_xprt_switch *xps,
{
if (unlikely(xprt == NULL))
return;
xps->xps_nactive--;
xps->xps_nxprts--;
if (xps->xps_nxprts == 0)
xps->xps_net = NULL;
@ -317,8 +319,24 @@ struct rpc_xprt *xprt_switch_find_next_entry_roundrobin(struct list_head *head,
static
struct rpc_xprt *xprt_iter_next_entry_roundrobin(struct rpc_xprt_iter *xpi)
{
return xprt_iter_next_entry_multiple(xpi,
struct rpc_xprt_switch *xps = rcu_dereference(xpi->xpi_xpswitch);
struct rpc_xprt *xprt;
unsigned long xprt_queuelen;
unsigned long xps_queuelen;
unsigned long xps_avglen;
do {
xprt = xprt_iter_next_entry_multiple(xpi,
xprt_switch_find_next_entry_roundrobin);
if (xprt == NULL)
break;
xprt_queuelen = atomic_long_read(&xprt->queuelen);
if (xprt_queuelen <= 2)
break;
xps_queuelen = atomic_long_read(&xps->xps_queuelen);
xps_avglen = DIV_ROUND_UP(xps_queuelen, xps->xps_nactive);
} while (xprt_queuelen > xps_avglen);
return xprt;
}
static