Return-Path: Received: from mail-io0-f196.google.com ([209.85.223.196]:32985 "EHLO mail-io0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751209AbcFXO43 (ORCPT ); Fri, 24 Jun 2016 10:56:29 -0400 Received: by mail-io0-f196.google.com with SMTP id t74so15637665ioi.0 for ; Fri, 24 Jun 2016 07:56:28 -0700 (PDT) From: Trond Myklebust To: bfields@fieldses.org Cc: linux-nfs@vger.kernel.org Subject: [PATCH 08/10] SUNRPC: Add a server side per-connection limit Date: Fri, 24 Jun 2016 10:55:50 -0400 Message-Id: <1466780152-7154-8-git-send-email-trond.myklebust@primarydata.com> In-Reply-To: <1466780152-7154-7-git-send-email-trond.myklebust@primarydata.com> References: <1466780152-7154-1-git-send-email-trond.myklebust@primarydata.com> <1466780152-7154-2-git-send-email-trond.myklebust@primarydata.com> <1466780152-7154-3-git-send-email-trond.myklebust@primarydata.com> <1466780152-7154-4-git-send-email-trond.myklebust@primarydata.com> <1466780152-7154-5-git-send-email-trond.myklebust@primarydata.com> <1466780152-7154-6-git-send-email-trond.myklebust@primarydata.com> <1466780152-7154-7-git-send-email-trond.myklebust@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: Allow the user to limit the number of requests serviced through a single connection. Signed-off-by: Trond Myklebust --- Documentation/kernel-parameters.txt | 6 ++++++ include/linux/sunrpc/svc.h | 1 + include/linux/sunrpc/svc_xprt.h | 1 + net/sunrpc/svc_xprt.c | 39 ++++++++++++++++++++++++++++++++++--- 4 files changed, 44 insertions(+), 3 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 82b42c958d1c..48ba6d2e670a 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3832,6 +3832,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. using these two parameters to set the minimum and maximum port values. + sunrpc.svc_rpc_per_connection_limit= + [NFS,SUNRPC] + Limit the number of requests that the server will + process in parallel from a single connection. + The default value is 0 (no limit). + sunrpc.pool_mode= [NFS] Control how the NFS server code allocates CPUs to diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 7ca44fb5b675..7321ae933867 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -268,6 +268,7 @@ struct svc_rqst { * cache pages */ #define RQ_VICTIM (5) /* about to be shut down */ #define RQ_BUSY (6) /* request is busy */ +#define RQ_DATA (7) /* request has data */ unsigned long rq_flags; /* flags field */ void * rq_argp; /* decoded arguments */ diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h index b7dabc4baafd..555c004de51e 100644 --- a/include/linux/sunrpc/svc_xprt.h +++ b/include/linux/sunrpc/svc_xprt.h @@ -69,6 +69,7 @@ struct svc_xprt { struct svc_serv *xpt_server; /* service for transport */ atomic_t xpt_reserved; /* space on outq that is rsvd */ + atomic_t xpt_nr_rqsts; /* Number of requests */ struct mutex xpt_mutex; /* to serialize sending data */ spinlock_t xpt_lock; /* protects sk_deferred * and xpt_auth_cache */ diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index eccc61237ca9..cd26d0d9e41f 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); @@ -327,12 +331,41 @@ 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_flags & ((1<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; @@ -514,8 +547,8 @@ 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); } @@ -783,7 +816,7 @@ 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, -- 2.7.4