From patchwork Sun Aug 3 17:03:03 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Trond Myklebust X-Patchwork-Id: 4665941 Return-Path: X-Original-To: patchwork-linux-nfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id EBFEB9F375 for ; Sun, 3 Aug 2014 17:03:24 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id F2AB3201C7 for ; Sun, 3 Aug 2014 17:03:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D8DE201BF for ; Sun, 3 Aug 2014 17:03:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752344AbaHCRDT (ORCPT ); Sun, 3 Aug 2014 13:03:19 -0400 Received: from mail-qg0-f48.google.com ([209.85.192.48]:41383 "EHLO mail-qg0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751822AbaHCRDR (ORCPT ); Sun, 3 Aug 2014 13:03:17 -0400 Received: by mail-qg0-f48.google.com with SMTP id i50so7989468qgf.35 for ; Sun, 03 Aug 2014 10:03:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=F0GO6sxs1ZrAe6l1iWZKn8xUJZs1RirU7m2GPB6S9pg=; b=bdqQp43Ww4jey+jxVYzrWj2duZ1q5CV2HDH7zrmFrKt4TxwZulMpiTNXmUGKO2AnBy OKmCcKhfhaiXDoywmOOS6reiWCKwZCCDlyfJVEDuTkfnb2W0k/W9UlCwBIMLmALBq1yQ rcDxBEsVdYuqTbuh9p1sDMouN7mxwcSkD4t8AW/WPXpoZYGYv/cewiQDPpqJMTz93koI lijCMOZfleLSrlQ8yBYk+tSTj69xtMDhv4XMGCWGWE+t0O6txLdoY6nM3fDM5m4F21dh nIoHUV0/dtcg4JdDCtn2csjZ8ss2GkVgEacriqdLKUSQ/Nce3IalJtg6OAI1h8vhjEei tmxQ== X-Gm-Message-State: ALoCoQmWcqxQKFy0FCwRIn0ONpRAh2jMiuo7bgONdgJzHrVIX5bhXclSWa3R4LaFZdYio1JPAZ1n X-Received: by 10.140.20.17 with SMTP id 17mr26976329qgi.85.1407085396093; Sun, 03 Aug 2014 10:03:16 -0700 (PDT) Received: from leira.trondhjem.org.localdomain (50-33-225-239.drr02.mskg.mi.frontiernet.net. [50.33.225.239]) by mx.google.com with ESMTPSA id a17sm6670702qac.1.2014.08.03.10.03.15 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 03 Aug 2014 10:03:15 -0700 (PDT) From: Trond Myklebust To: Bruce Fields Cc: linux-nfs@vger.kernel.org Subject: [PATCH 01/11] SUNRPC: Reduce contention in svc_xprt_enqueue() Date: Sun, 3 Aug 2014 13:03:03 -0400 Message-Id: <1407085393-3175-2-git-send-email-trond.myklebust@primarydata.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1407085393-3175-1-git-send-email-trond.myklebust@primarydata.com> References: <1407085393-3175-1-git-send-email-trond.myklebust@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Ensure that all calls to svc_xprt_enqueue() except svc_xprt_received() check the value of XPT_BUSY, before attempting to grab spinlocks etc. This is to avoid situations such as the following "perf" trace, which shows heavy contention on the pool spinlock: 54.15% nfsd [kernel.kallsyms] [k] _raw_spin_lock_bh | --- _raw_spin_lock_bh | |--71.43%-- svc_xprt_enqueue | | | |--50.31%-- svc_reserve | | | |--31.35%-- svc_xprt_received | | | |--18.34%-- svc_tcp_data_ready ... Signed-off-by: Trond Myklebust --- net/sunrpc/svc_xprt.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index b4737fbdec13..54a761fa6351 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -23,6 +23,7 @@ static int svc_deferred_recv(struct svc_rqst *rqstp); static struct cache_deferred_req *svc_defer(struct cache_req *req); static void svc_age_temp_xprts(unsigned long closure); static void svc_delete_xprt(struct svc_xprt *xprt); +static void svc_xprt_do_enqueue(struct svc_xprt *xprt); /* apparently the "standard" is that clients close * idle connections after 5 minutes, servers after @@ -222,11 +223,12 @@ static void svc_xprt_received(struct svc_xprt *xprt) if (!test_bit(XPT_BUSY, &xprt->xpt_flags)) return; /* As soon as we clear busy, the xprt could be closed and - * 'put', so we need a reference to call svc_xprt_enqueue with: + * 'put', so we need a reference to call svc_xprt_do_enqueue with: */ svc_xprt_get(xprt); + smp_mb__before_clear_bit(); clear_bit(XPT_BUSY, &xprt->xpt_flags); - svc_xprt_enqueue(xprt); + svc_xprt_do_enqueue(xprt); svc_xprt_put(xprt); } @@ -335,12 +337,7 @@ static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt) return false; } -/* - * Queue up a transport with data pending. If there are idle nfsd - * processes, wake 'em up. - * - */ -void svc_xprt_enqueue(struct svc_xprt *xprt) +static void svc_xprt_do_enqueue(struct svc_xprt *xprt) { struct svc_pool *pool; struct svc_rqst *rqstp; @@ -398,6 +395,18 @@ void svc_xprt_enqueue(struct svc_xprt *xprt) out_unlock: spin_unlock_bh(&pool->sp_lock); } + +/* + * Queue up a transport with data pending. If there are idle nfsd + * processes, wake 'em up. + * + */ +void svc_xprt_enqueue(struct svc_xprt *xprt) +{ + if (test_bit(XPT_BUSY, &xprt->xpt_flags)) + return; + svc_xprt_do_enqueue(xprt); +} EXPORT_SYMBOL_GPL(svc_xprt_enqueue); /*