From patchwork Thu Jun 29 18:42:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13297203 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 46C06C0015E for ; Thu, 29 Jun 2023 18:42:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232799AbjF2Smy (ORCPT ); Thu, 29 Jun 2023 14:42:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232813AbjF2Smy (ORCPT ); Thu, 29 Jun 2023 14:42:54 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99D6B2681 for ; Thu, 29 Jun 2023 11:42:52 -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 2C4F3615E4 for ; Thu, 29 Jun 2023 18:42:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2023EC433C8; Thu, 29 Jun 2023 18:42:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688064171; bh=uuaHQhmmL7ku0nyVaFEQ9qlHbmFEZv9i0J/O3Fzz1tw=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=rwoKD3iu8OrL110JrjVuvWFf30IMh4npTv1OnDGjD6YVDGBw/L81URBu2hqsjPbd+ FNz8WJDAp3/PwgWrSnaZbGdcuRk9ikpJBt9IxySCFnzgIfZc3GDptLDOwJaA252ZD9 BvxDi2HPWGy8aobcuSyCHNuBt3kXAZFAguMJ5T/Ihk2nW0Lf8YxA78jRrsx7Pld9XG Ete+KYQoOTvAF5I7Wq2xbEgBaYRnOm5aN09Ksy7kNV/qaaQCTSt+93ewxddYZVh0Vo CYlvXXWcz2c6cbNyX5QjBSSiZU3GSmmVMGoA5yXcb7WVeS6eS4/OkfMZnV8mqEVzwk THlePelOQkd5w== Subject: [PATCH RFC 4/8] SUNRPC: Clean up svc_set_num_threads 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 14:42:50 -0400 Message-ID: <168806417022.1034990.13187981091421789973.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 Document the API contract and remove stale or obvious comments. Signed-off-by: Chuck Lever --- net/sunrpc/svc.c | 60 +++++++++++++++++++++++------------------------------- 1 file changed, 25 insertions(+), 35 deletions(-) diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 04151e22ec44..cf2e58ead35d 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -724,23 +724,14 @@ struct svc_rqst *svc_pool_wake_idle_thread(struct svc_serv *serv, return NULL; } -/* - * Choose a pool in which to create a new thread, for svc_set_num_threads - */ -static inline struct svc_pool * -choose_pool(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) +static struct svc_pool * +svc_pool_next(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) { - if (pool != NULL) - return pool; - - return &serv->sv_pools[(*state)++ % serv->sv_nrpools]; + return pool ? pool : &serv->sv_pools[(*state)++ % serv->sv_nrpools]; } -/* - * Choose a thread to kill, for svc_set_num_threads - */ -static inline struct task_struct * -choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) +static struct task_struct * +svc_pool_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) { unsigned int i; struct task_struct *task = NULL; @@ -748,7 +739,6 @@ choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) if (pool != NULL) { spin_lock_bh(&pool->sp_lock); } else { - /* choose a pool in round-robin fashion */ for (i = 0; i < serv->sv_nrpools; i++) { pool = &serv->sv_pools[--(*state) % serv->sv_nrpools]; spin_lock_bh(&pool->sp_lock); @@ -763,21 +753,15 @@ choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) if (!list_empty(&pool->sp_all_threads)) { struct svc_rqst *rqstp; - /* - * Remove from the pool->sp_all_threads list - * so we don't try to kill it again. - */ rqstp = list_entry(pool->sp_all_threads.next, struct svc_rqst, rq_all); set_bit(RQ_VICTIM, &rqstp->rq_flags); list_del_rcu(&rqstp->rq_all); task = rqstp->rq_task; } spin_unlock_bh(&pool->sp_lock); - return task; } -/* create new threads */ static int svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) { @@ -789,13 +773,12 @@ svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) do { nrservs--; - chosen_pool = choose_pool(serv, pool, &state); - + chosen_pool = svc_pool_next(serv, pool, &state); node = svc_pool_map_get_node(chosen_pool->sp_id); + rqstp = svc_prepare_thread(serv, chosen_pool, node); if (IS_ERR(rqstp)) return PTR_ERR(rqstp); - task = kthread_create_on_node(serv->sv_threadfn, rqstp, node, "%s", serv->sv_name); if (IS_ERR(task)) { @@ -814,15 +797,6 @@ svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) return 0; } -/* - * Create or destroy enough new threads to make the number - * of threads the given number. If `pool' is non-NULL, applies - * only to threads in that pool, otherwise round-robins between - * all pools. Caller must ensure that mutual exclusion between this and - * server startup or shutdown. - */ - -/* destroy old threads */ static int svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) { @@ -830,9 +804,8 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) struct task_struct *task; unsigned int state = serv->sv_nrthreads-1; - /* destroy old threads */ do { - task = choose_victim(serv, pool, &state); + task = svc_pool_victim(serv, pool, &state); if (task == NULL) break; rqstp = kthread_data(task); @@ -844,6 +817,23 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) return 0; } +/** + * svc_set_num_threads - adjust number of threads per RPC service + * @serv: RPC service to adjust + * @pool: Specific pool from which to choose threads, or NULL + * @nrservs: New number of threads for @serv (0 or less means kill all threads) + * + * Create or destroy threads to make the number of threads for @serv the + * given number. If @pool is non-NULL, change only threads in that pool; + * otherwise, round-robin between all pools for @serv. @serv's + * sv_nrthreads is adjusted for each thread created or destroyed. + * + * Caller must ensure mutual exclusion between this and server startup or + * shutdown. + * + * Returns zero on success or a negative errno if an error occurred while + * starting a thread. + */ int svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) {