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authorTrond Myklebust <trond.myklebust@primarydata.com>2016-06-24 10:55:50 -0400
committerJ. Bruce Fields <bfields@redhat.com>2016-07-13 15:53:48 -0400
commitff3ac5c3dc2323ba54c3d9ef30ef4942a71b251d (patch)
tree5efd439be1327a0c48c9103336e113186d3051cd /net/sunrpc
parent4720b0703a0dfcd6da6a308ea71aaacc55beade7 (diff)
SUNRPC: Add a server side per-connection limit
Allow the user to limit the number of requests serviced through a single connection, to help prevent faster clients from starving slower clients. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/svc_xprt.c39
1 files changed, 36 insertions, 3 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index e7082a4aeb56..2adc8db6aaf5 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -21,6 +21,10 @@
#define RPCDBG_FACILITY RPCDBG_SVCXPRT
+static unsigned int svc_rpc_per_connection_limit __read_mostly;
+module_param(svc_rpc_per_connection_limit, uint, 0644);
+
+
static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt);
static int svc_deferred_recv(struct svc_rqst *rqstp);
static struct cache_deferred_req *svc_defer(struct cache_req *req);
@@ -329,12 +333,41 @@ char *svc_print_addr(struct svc_rqst *rqstp, char *buf, size_t len)
}
EXPORT_SYMBOL_GPL(svc_print_addr);
+static bool svc_xprt_slots_in_range(struct svc_xprt *xprt)
+{
+ unsigned int limit = svc_rpc_per_connection_limit;
+ int nrqsts = atomic_read(&xprt->xpt_nr_rqsts);
+
+ return limit == 0 || (nrqsts >= 0 && nrqsts < limit);
+}
+
+static bool svc_xprt_reserve_slot(struct svc_rqst *rqstp, struct svc_xprt *xprt)
+{
+ if (!test_bit(RQ_DATA, &rqstp->rq_flags)) {
+ if (!svc_xprt_slots_in_range(xprt))
+ return false;
+ atomic_inc(&xprt->xpt_nr_rqsts);
+ set_bit(RQ_DATA, &rqstp->rq_flags);
+ }
+ return true;
+}
+
+static void svc_xprt_release_slot(struct svc_rqst *rqstp)
+{
+ struct svc_xprt *xprt = rqstp->rq_xprt;
+ if (test_and_clear_bit(RQ_DATA, &rqstp->rq_flags)) {
+ atomic_dec(&xprt->xpt_nr_rqsts);
+ svc_xprt_enqueue(xprt);
+ }
+}
+
static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
{
if (xprt->xpt_flags & ((1<<XPT_CONN)|(1<<XPT_CLOSE)))
return true;
if (xprt->xpt_flags & ((1<<XPT_DATA)|(1<<XPT_DEFERRED))) {
- if (xprt->xpt_ops->xpo_has_wspace(xprt))
+ if (xprt->xpt_ops->xpo_has_wspace(xprt) &&
+ svc_xprt_slots_in_range(xprt))
return true;
trace_svc_xprt_no_write_space(xprt);
return false;
@@ -516,8 +549,8 @@ static void svc_xprt_release(struct svc_rqst *rqstp)
rqstp->rq_res.head[0].iov_len = 0;
svc_reserve(rqstp, 0);
+ svc_xprt_release_slot(rqstp);
rqstp->rq_xprt = NULL;
-
svc_xprt_put(xprt);
}
@@ -785,7 +818,7 @@ static int svc_handle_xprt(struct svc_rqst *rqstp, struct svc_xprt *xprt)
svc_add_new_temp_xprt(serv, newxpt);
else
module_put(xprt->xpt_class->xcl_owner);
- } else {
+ } else if (svc_xprt_reserve_slot(rqstp, xprt)) {
/* XPT_DATA|XPT_DEFERRED case: */
dprintk("svc: server %p, pool %u, transport %p, inuse=%d\n",
rqstp, rqstp->rq_pool->sp_id, xprt,