From patchwork Thu Jan 14 16:22:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 12020239 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A98CC4332B for ; Thu, 14 Jan 2021 16:23:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CC7423B40 for ; Thu, 14 Jan 2021 16:23:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726283AbhANQXW (ORCPT ); Thu, 14 Jan 2021 11:23:22 -0500 Received: from mail.kernel.org ([198.145.29.99]:45796 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726241AbhANQXW (ORCPT ); Thu, 14 Jan 2021 11:23:22 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 28AF723B40; Thu, 14 Jan 2021 16:22:41 +0000 (UTC) Subject: [PATCH v1 2/5] svcrdma: Convert rdma_stat_recv to a per-CPU counter From: Chuck Lever To: linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org Date: Thu, 14 Jan 2021 11:22:40 -0500 Message-ID: <161064136043.6061.10720720567534020811.stgit@klimt.1015granger.net> In-Reply-To: <161064114388.6061.6808790429789225779.stgit@klimt.1015granger.net> References: <161064114388.6061.6808790429789225779.stgit@klimt.1015granger.net> User-Agent: StGit/0.23-29-ga622f1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Receives are frequent events. Avoid the overhead of a memory bus lock cycle for counting a value that is hardly every used. Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc_rdma.h | 3 +- net/sunrpc/xprtrdma/svc_rdma.c | 55 +++++++++++++++++++++++++++++-- net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 3 +- 3 files changed, 54 insertions(+), 7 deletions(-) diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h index 294b56e61522..ff32c59a27e7 100644 --- a/include/linux/sunrpc/svc_rdma.h +++ b/include/linux/sunrpc/svc_rdma.h @@ -49,6 +49,7 @@ #include #include +#include #include #include @@ -65,7 +66,7 @@ extern unsigned int svcrdma_max_requests; extern unsigned int svcrdma_max_bc_requests; extern unsigned int svcrdma_max_req_size; -extern atomic_t rdma_stat_recv; +extern struct percpu_counter svcrdma_stat_recv; extern atomic_t rdma_stat_read; extern atomic_t rdma_stat_write; extern atomic_t rdma_stat_sq_starve; diff --git a/net/sunrpc/xprtrdma/svc_rdma.c b/net/sunrpc/xprtrdma/svc_rdma.c index 1fc1d5cbeb9b..3e5e622bad81 100644 --- a/net/sunrpc/xprtrdma/svc_rdma.c +++ b/net/sunrpc/xprtrdma/svc_rdma.c @@ -63,7 +63,7 @@ unsigned int svcrdma_max_req_size = RPCRDMA_DEF_INLINE_THRESH; static unsigned int min_max_inline = RPCRDMA_DEF_INLINE_THRESH; static unsigned int max_max_inline = RPCRDMA_MAX_INLINE_THRESH; -atomic_t rdma_stat_recv; +struct percpu_counter svcrdma_stat_recv; atomic_t rdma_stat_read; atomic_t rdma_stat_write; atomic_t rdma_stat_sq_starve; @@ -110,6 +110,42 @@ static int read_reset_stat(struct ctl_table *table, int write, return 0; } +enum { + SVCRDMA_COUNTER_BUFSIZ = sizeof(unsigned long long), +}; + +static int svcrdma_counter_handler(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + struct percpu_counter *stat = (struct percpu_counter *)table->data; + char tmp[SVCRDMA_COUNTER_BUFSIZ + 1]; + int len; + + if (write) { + percpu_counter_set(stat, 0); + return 0; + } + + len = snprintf(tmp, SVCRDMA_COUNTER_BUFSIZ, "%lld\n", + percpu_counter_sum_positive(stat)); + if (len >= SVCRDMA_COUNTER_BUFSIZ) + return -EFAULT; + len = strlen(tmp); + if (*ppos > len) { + *lenp = 0; + return 0; + } + len -= *ppos; + if (len > *lenp) + len = *lenp; + if (len) + memcpy(buffer, tmp, len); + *lenp = len; + *ppos += len; + + return 0; +} + static struct ctl_table_header *svcrdma_table_header; static struct ctl_table svcrdma_parm_table[] = { { @@ -149,10 +185,10 @@ static struct ctl_table svcrdma_parm_table[] = { }, { .procname = "rdma_stat_recv", - .data = &rdma_stat_recv, - .maxlen = sizeof(atomic_t), + .data = &svcrdma_stat_recv, + .maxlen = SVCRDMA_COUNTER_BUFSIZ, .mode = 0644, - .proc_handler = read_reset_stat, + .proc_handler = svcrdma_counter_handler, }, { .procname = "rdma_stat_write", @@ -230,15 +266,26 @@ static void svc_rdma_proc_cleanup(void) return; unregister_sysctl_table(svcrdma_table_header); svcrdma_table_header = NULL; + + percpu_counter_destroy(&svcrdma_stat_recv); } static int svc_rdma_proc_init(void) { + int rc; + if (svcrdma_table_header) return 0; + rc = percpu_counter_init(&svcrdma_stat_recv, 0, GFP_KERNEL); + if (rc) + goto out_err; + svcrdma_table_header = register_sysctl_table(svcrdma_root_table); return 0; + +out_err: + return rc; } void svc_rdma_cleanup(void) diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index cbdb71247755..7d14a74df716 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -845,8 +845,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) } list_del(&ctxt->rc_list); spin_unlock(&rdma_xprt->sc_rq_dto_lock); - - atomic_inc(&rdma_stat_recv); + percpu_counter_inc(&svcrdma_stat_recv); svc_rdma_build_arg_xdr(rqstp, ctxt);