From mboxrd@z Thu Jan 1 00:00:00 1970 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 722EAC433F5 for ; Fri, 14 Jan 2022 22:05:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ED4176B00E1; Fri, 14 Jan 2022 17:05:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E84116B00E3; Fri, 14 Jan 2022 17:05:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D4C426B00E2; Fri, 14 Jan 2022 17:05:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0226.hostedemail.com [216.40.44.226]) by kanga.kvack.org (Postfix) with ESMTP id C27666B00DF for ; Fri, 14 Jan 2022 17:05:31 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 82BE298C14 for ; Fri, 14 Jan 2022 22:05:28 +0000 (UTC) X-FDA: 79030274736.10.0C02F32 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf28.hostedemail.com (Postfix) with ESMTP id 16A5DC0008 for ; Fri, 14 Jan 2022 22:05:27 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7DB2E61FF6; Fri, 14 Jan 2022 22:05:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BAAFDC36AE5; Fri, 14 Jan 2022 22:05:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1642197926; bh=A6orIj7zEKCwqVSN/lU708h9PEkKG+pv4FQp8bVap30=; h=Date:From:To:Subject:In-Reply-To:From; b=AZ5qYlpTZijVLdEZWCzhit5/fGinmeBPhnN4dBLAwG3jvetQYB/4j/3pysm0u3cUv 5cueOj4F88qZseM580hGBsObrDAXncZmpmsZ1S/dsPle+Hw9MoQwO+RBmFCrWbX6nw zf58UrTar/O6zwgeLV1PvJaQFY0LlhkSXTAS59KU= Date: Fri, 14 Jan 2022 14:05:26 -0800 From: Andrew Morton To: akpm@linux-foundation.org, christophe.jaillet@wanadoo.fr, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 047/146] mm/frontswap.c: use non-atomic '__set_bit()' when possible Message-ID: <20220114220526.Av3FTFVPw%akpm@linux-foundation.org> In-Reply-To: <20220114140222.6b14f0061194d3200000c52d@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: 16A5DC0008 X-Stat-Signature: i566znksc41mfedwb7497g8pj7umerho Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=AZ5qYlpT; dmarc=none; spf=pass (imf28.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam03 X-HE-Tag: 1642197927-637623 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Christophe JAILLET Subject: mm/frontswap.c: use non-atomic '__set_bit()' when possible the 'a' and 'b' bitmaps are local to this function, so no concurrent access can occur. So the non-atomic '__set_bit()' can be used to save a few cycles. Link: https://lkml.kernel.org/r/e52476da5cee57151745c5c3c934a69798dc6fa4.1638132190.git.christophe.jaillet@wanadoo.fr Signed-off-by: Christophe JAILLET Signed-off-by: Andrew Morton --- mm/frontswap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/frontswap.c~mm-mempool-use-non-atomic-__set_bit-when-possible +++ a/mm/frontswap.c @@ -127,7 +127,7 @@ void frontswap_register_ops(struct front spin_lock(&swap_lock); plist_for_each_entry(si, &swap_active_head, list) { if (!WARN_ON(!si->frontswap_map)) - set_bit(si->type, a); + __set_bit(si->type, a); } spin_unlock(&swap_lock); @@ -149,7 +149,7 @@ void frontswap_register_ops(struct front spin_lock(&swap_lock); plist_for_each_entry(si, &swap_active_head, list) { if (si->frontswap_map) - set_bit(si->type, b); + __set_bit(si->type, b); } spin_unlock(&swap_lock); _