From patchwork Thu Jul 20 09:45:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chengming Zhou X-Patchwork-Id: 13320241 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 41005EB64DA for ; Thu, 20 Jul 2023 09:49:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230371AbjGTJtl (ORCPT ); Thu, 20 Jul 2023 05:49:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230400AbjGTJsp (ORCPT ); Thu, 20 Jul 2023 05:48:45 -0400 Received: from out-51.mta0.migadu.com (out-51.mta0.migadu.com [91.218.175.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CFC683AAD for ; Thu, 20 Jul 2023 02:47:36 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1689846454; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=p34J6xnRb86eKyDcpXgSq81rjV9gO+WCulIJcSmybAc=; b=FO6tJlnKG0PcTyIP5O724vhJaUPzs5PqLkd247BAIxAFGdYM4v7WurTFDGaN1YoOreq4c4 b/h8BL7Yc08WxbDl3yG4Uw0l/8qSIJEuH5EsaTErtlXjMS1BEQPE+uV6BtlyiezOPVg7ob IdnA189BksTiUPxZouFvEL2EiJX56tI= From: chengming.zhou@linux.dev To: axboe@kernel.dk, osandov@fb.com, ming.lei@redhat.com, kbusch@kernel.org, krisman@suse.de Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, zhouchengming@bytedance.com Subject: [PATCH 5/6] sbitmap: wake_index doesn't need to be atomic_t Date: Thu, 20 Jul 2023 17:45:54 +0800 Message-ID: <20230720094555.1397621-6-chengming.zhou@linux.dev> In-Reply-To: <20230720094555.1397621-1-chengming.zhou@linux.dev> References: <20230720094555.1397621-1-chengming.zhou@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Chengming Zhou We use wake_index to remember from which to wake up next time, which doesn't need to be atomic_t since we only read it once before wakeups, and write it once after wakeups. Signed-off-by: Chengming Zhou --- include/linux/sbitmap.h | 2 +- lib/sbitmap.c | 12 ++++++------ 2 files changed, 7 insertions(+), 7 deletions(-) diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h index d662cf136021..bdbe478ba4dc 100644 --- a/include/linux/sbitmap.h +++ b/include/linux/sbitmap.h @@ -116,7 +116,7 @@ struct sbitmap_queue { /** * @wake_index: Next wait queue in @ws to wake up. */ - atomic_t wake_index; + unsigned int wake_index; /** * @ws: Wait queues. diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 50bdf3a31947..6778ab3fc6a5 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -419,7 +419,7 @@ int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth, sbq->min_shallow_depth = UINT_MAX; sbq->wake_batch = sbq_calc_wake_batch(sbq, depth); - atomic_set(&sbq->wake_index, 0); + sbq->wake_index = 0; atomic_set(&sbq->ws_active, 0); atomic_set(&sbq->completion_cnt, 0); atomic_set(&sbq->wakeup_cnt, 0); @@ -549,7 +549,7 @@ static void __sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr) if (!atomic_read(&sbq->ws_active)) return; - wake_index = atomic_read(&sbq->wake_index); + wake_index = READ_ONCE(sbq->wake_index); for (i = 0; i < SBQ_WAIT_QUEUES; i++) { struct sbq_wait_state *ws = &sbq->ws[wake_index]; @@ -570,8 +570,8 @@ static void __sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr) break; } - if (wake_index != atomic_read(&sbq->wake_index)) - atomic_set(&sbq->wake_index, wake_index); + if (wake_index != READ_ONCE(sbq->wake_index)) + WRITE_ONCE(sbq->wake_index, wake_index); } void sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr) @@ -672,7 +672,7 @@ void sbitmap_queue_wake_all(struct sbitmap_queue *sbq) * sbitmap_queue_wake_up(). */ smp_mb(); - wake_index = atomic_read(&sbq->wake_index); + wake_index = READ_ONCE(sbq->wake_index); for (i = 0; i < SBQ_WAIT_QUEUES; i++) { struct sbq_wait_state *ws = &sbq->ws[wake_index]; @@ -702,7 +702,7 @@ void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m) seq_puts(m, "}\n"); seq_printf(m, "wake_batch=%u\n", sbq->wake_batch); - seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index)); + seq_printf(m, "wake_index=%d\n", READ_ONCE(sbq->wake_index)); seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active)); seq_puts(m, "ws={\n");