From nobody Mon Feb 9 04:28:54 2026 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 7FA7FEB64DD for ; Thu, 20 Jul 2023 09:49:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229685AbjGTJte (ORCPT ); Thu, 20 Jul 2023 05:49:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229652AbjGTJs2 (ORCPT ); Thu, 20 Jul 2023 05:48:28 -0400 Received: from out-18.mta0.migadu.com (out-18.mta0.migadu.com [IPv6:2001:41d0:1004:224b::12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 678DB26A5 for ; Thu, 20 Jul 2023 02:47:32 -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=1689846450; 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=CHTcss6l/Dml/Uch+o0A/n+25yQoOIqj7dE4TlbyHH4=; b=Ai++OZMUjHmw2983yCNBjVkPFxFeR1arX5zXXbaGjA90hfi5mvTPK+xbJURrXi/u+0CWWN RkZhb6KGm+bKwEOt2ud4UlHdP4VWFqqslwKhjxgk4nP6y8kd6taike6pQ5cLKPz4EMMIpE 7N58wZ4pmp7tHfkumvcPMa3P5e/aYD4= 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 4/6] sbitmap: remove offset wrap logic when finding bit in word Date: Thu, 20 Jul 2023 17:45:53 +0800 Message-ID: <20230720094555.1397621-5-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 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Chengming Zhou We actually don't need the offset hint wrap logic in word: 1. Strict round-robin mode: just search from that offset hint, we will recheck that word at last if offset hint > 0. 2. No round-robin mode: we use offset hint =3D=3D 0, so don't need to wrap offset hint too. We remove offset wrap logic and simplify the code. Signed-off-by: Chengming Zhou --- lib/sbitmap.c | 36 ++++++++++-------------------------- 1 file changed, 10 insertions(+), 26 deletions(-) diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 0f3943bd3940..50bdf3a31947 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -134,34 +134,21 @@ void sbitmap_resize(struct sbitmap *sb, unsigned int = depth) EXPORT_SYMBOL_GPL(sbitmap_resize); =20 static int __sbitmap_get_word(unsigned long *word, unsigned long depth, - unsigned int hint, bool wrap) + unsigned int hint) { int nr; =20 - /* don't wrap if starting from 0 */ - wrap =3D wrap && hint; - while (1) { nr =3D find_next_zero_bit(word, depth, hint); - if (unlikely(nr >=3D depth)) { - if (wrap) { - hint =3D 0; - continue; - } + if (unlikely(nr >=3D depth)) return -1; - } =20 if (!test_and_set_bit_lock(nr, word)) break; =20 hint =3D nr + 1; - if (hint >=3D depth) { - if (wrap) { - hint =3D 0; - continue; - } + if (hint >=3D depth) return -1; - } } =20 return nr; @@ -169,14 +156,13 @@ static int __sbitmap_get_word(unsigned long *word, un= signed long depth, =20 static int sbitmap_find_bit_in_word(struct sbitmap_word *map, unsigned int depth, - unsigned int alloc_hint, - bool wrap) + unsigned int alloc_hint) { int nr; =20 do { nr =3D __sbitmap_get_word(&map->word, depth, - alloc_hint, wrap); + alloc_hint); if (nr !=3D -1) break; if (!sbitmap_deferred_clear(map)) @@ -189,8 +175,7 @@ static int sbitmap_find_bit_in_word(struct sbitmap_word= *map, static int sbitmap_find_bit(struct sbitmap *sb, unsigned int depth, unsigned int index, - unsigned int alloc_hint, - bool wrap) + unsigned int alloc_hint) { unsigned int map_nr =3D sb->map_nr; unsigned int i; @@ -200,7 +185,7 @@ static int sbitmap_find_bit(struct sbitmap *sb, * If we have alloc_hint > 0 and don't wrap, we need to * recheck sb->map[index] with hint =3D=3D 0 to exhaust the map. */ - if (alloc_hint && !wrap) + if (alloc_hint) map_nr +=3D 1; =20 for (i =3D 0; i < map_nr; i++) { @@ -208,7 +193,7 @@ static int sbitmap_find_bit(struct sbitmap *sb, min_t(unsigned int, __map_depth(sb, index), depth), - alloc_hint, wrap); + alloc_hint); =20 if (nr !=3D -1) { nr +=3D index << sb->shift; @@ -240,8 +225,7 @@ static int __sbitmap_get(struct sbitmap *sb, unsigned i= nt alloc_hint) else alloc_hint =3D 0; =20 - return sbitmap_find_bit(sb, UINT_MAX, index, alloc_hint, - !sb->round_robin); + return sbitmap_find_bit(sb, UINT_MAX, index, alloc_hint); } =20 int sbitmap_get(struct sbitmap *sb) @@ -272,7 +256,7 @@ static int __sbitmap_get_shallow(struct sbitmap *sb, /* No point in looping twice in find_next_zero_bit() for this case. */ alloc_hint =3D 0; =20 - return sbitmap_find_bit(sb, shallow_depth, index, alloc_hint, true); + return sbitmap_find_bit(sb, shallow_depth, index, alloc_hint); } =20 int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth) --=20 2.41.0