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| author | Trond Myklebust <trond.myklebust@primarydata.com> | 2016-06-24 10:55:50 -0400 |
|---|---|---|
| committer | J. Bruce Fields <bfields@redhat.com> | 2016-07-13 15:53:48 -0400 |
| commit | ff3ac5c3dc2323ba54c3d9ef30ef4942a71b251d (patch) | |
| tree | 5efd439be1327a0c48c9103336e113186d3051cd /net/sunrpc/svc_xprt.c | |
| parent | 4720b0703a0dfcd6da6a308ea71aaacc55beade7 (diff) | |
| download | lwn-ff3ac5c3dc2323ba54c3d9ef30ef4942a71b251d.tar.gz lwn-ff3ac5c3dc2323ba54c3d9ef30ef4942a71b251d.zip | |
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/svc_xprt.c')
| -rw-r--r-- | net/sunrpc/svc_xprt.c | 39 |
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, |