From patchwork Thu Jun 29 18:42:30 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13297200 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 898E5EB64D9 for ; Thu, 29 Jun 2023 18:42:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232785AbjF2Smg (ORCPT ); Thu, 29 Jun 2023 14:42:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57362 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232774AbjF2Smf (ORCPT ); Thu, 29 Jun 2023 14:42:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0A4CD2681 for ; Thu, 29 Jun 2023 11:42:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6BB66615E4 for ; Thu, 29 Jun 2023 18:42:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 648B0C433C8; Thu, 29 Jun 2023 18:42:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688064151; bh=Y7Tjzr9QJE6XOLQMLihT+VYtx/00IbvTy/FXe+QmMww=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=UQbJnh1MgCg3uc5vjuv0zgmej8LNCVyUl85eJrpI5Ces53K+OoaDBsFm2RROTndy4 R1kNlEUdFQF/WK1qRlGTz5FBKFmma4bJ5phKmvo47onRad/Hx+Kp2yoLRJbP6kSBuF njIkBduyj2P7GhCRI1SIf5xvtmmgknI/ZEkLAKuvhj5GdxxZJBvhDK9ulKmr7xnRiC LF6ojoY3bbaaFkbMvD7Rpb+7SWORO4EPIeeM7J1hHKGu9Xy/aMGQrQw1rs6FpGUQOM /P7T8k1zyNr0Scl4KpITEVdMWamp2+6jL2SNBwqXjSGISLGPXdqBHFik6kmmP+JQ2m eEpOlJ855o2zw== Subject: [PATCH RFC 1/8] SUNRPC: Deduplicate thread wake-up code From: Chuck Lever To: linux-nfs@vger.kernel.org Cc: Chuck Lever , lorenzo@kernel.org, neilb@suse.de, jlayton@redhat.com, david@fromorbit.com Date: Thu, 29 Jun 2023 14:42:30 -0400 Message-ID: <168806415041.1034990.11822594910002824781.stgit@morisot.1015granger.net> In-Reply-To: <168806401782.1034990.9686296943273298604.stgit@morisot.1015granger.net> References: <168806401782.1034990.9686296943273298604.stgit@morisot.1015granger.net> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Chuck Lever Refactor: Extract the loop that finds an idle service thread from svc_xprt_enqueue() and svc_wake_up(). Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc.h | 1 + net/sunrpc/svc.c | 28 +++++++++++++++++++++++++++ net/sunrpc/svc_xprt.c | 46 +++++++++++++------------------------------- 3 files changed, 43 insertions(+), 32 deletions(-) diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index f8751118c122..dc2d90a655e2 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -427,6 +427,7 @@ int svc_register(const struct svc_serv *, struct net *, const int, void svc_wake_up(struct svc_serv *); void svc_reserve(struct svc_rqst *rqstp, int space); +struct svc_rqst *svc_pool_wake_idle_thread(struct svc_pool *pool); struct svc_pool *svc_pool_for_cpu(struct svc_serv *serv); char * svc_print_addr(struct svc_rqst *, char *, size_t); const char * svc_proc_name(const struct svc_rqst *rqstp); diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 587811a002c9..e81ce5f76abd 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -689,6 +689,34 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node) return rqstp; } +/** + * svc_pool_wake_idle_thread - wake an idle thread in @pool + * @pool: service thread pool + * + * Returns an idle service thread (now marked BUSY), or NULL + * if no service threads are available. Finding an idle service + * thread and marking it BUSY is atomic with respect to other + * calls to svc_pool_wake_idle_thread(). + */ +struct svc_rqst *svc_pool_wake_idle_thread(struct svc_pool *pool) +{ + struct svc_rqst *rqstp; + + rcu_read_lock(); + list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) { + if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags)) + continue; + + rcu_read_unlock(); + WRITE_ONCE(rqstp->rq_qtime, ktime_get()); + wake_up_process(rqstp->rq_task); + percpu_counter_inc(&pool->sp_threads_woken); + return rqstp; + } + rcu_read_unlock(); + return NULL; +} + /* * Choose a pool in which to create a new thread, for svc_set_num_threads */ diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index 62c7919ea610..f14476d11b67 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -455,8 +455,8 @@ static bool svc_xprt_ready(struct svc_xprt *xprt) */ void svc_xprt_enqueue(struct svc_xprt *xprt) { + struct svc_rqst *rqstp; struct svc_pool *pool; - struct svc_rqst *rqstp = NULL; if (!svc_xprt_ready(xprt)) return; @@ -476,20 +476,10 @@ void svc_xprt_enqueue(struct svc_xprt *xprt) list_add_tail(&xprt->xpt_ready, &pool->sp_sockets); spin_unlock_bh(&pool->sp_lock); - /* find a thread for this xprt */ - rcu_read_lock(); - list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) { - if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags)) - continue; - percpu_counter_inc(&pool->sp_threads_woken); - rqstp->rq_qtime = ktime_get(); - wake_up_process(rqstp->rq_task); - goto out_unlock; - } - set_bit(SP_CONGESTED, &pool->sp_flags); - rqstp = NULL; -out_unlock: - rcu_read_unlock(); + rqstp = svc_pool_wake_idle_thread(pool); + if (!rqstp) + set_bit(SP_CONGESTED, &pool->sp_flags); + trace_svc_xprt_enqueue(xprt, rqstp); } EXPORT_SYMBOL_GPL(svc_xprt_enqueue); @@ -581,7 +571,10 @@ static void svc_xprt_release(struct svc_rqst *rqstp) svc_xprt_put(xprt); } -/* +/** + * svc_wake_up - Wake up a service thread for non-transport work + * @serv: RPC service + * * Some svc_serv's will have occasional work to do, even when a xprt is not * waiting to be serviced. This function is there to "kick" a task in one of * those services so that it can wake up and do that work. Note that we only @@ -590,27 +583,16 @@ static void svc_xprt_release(struct svc_rqst *rqstp) */ void svc_wake_up(struct svc_serv *serv) { + struct svc_pool *pool = &serv->sv_pools[0]; struct svc_rqst *rqstp; - struct svc_pool *pool; - pool = &serv->sv_pools[0]; - - rcu_read_lock(); - list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) { - /* skip any that aren't queued */ - if (test_bit(RQ_BUSY, &rqstp->rq_flags)) - continue; - rcu_read_unlock(); - wake_up_process(rqstp->rq_task); - trace_svc_wake_up(rqstp->rq_task->pid); + rqstp = svc_pool_wake_idle_thread(pool); + if (!rqstp) { + set_bit(SP_TASK_PENDING, &pool->sp_flags); return; } - rcu_read_unlock(); - /* No free entries available */ - set_bit(SP_TASK_PENDING, &pool->sp_flags); - smp_wmb(); - trace_svc_wake_up(0); + trace_svc_wake_up(rqstp->rq_task->pid); } EXPORT_SYMBOL_GPL(svc_wake_up);