From nobody Wed Dec 17 08:00:04 2025 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 4841BC41513 for ; Tue, 17 Oct 2023 01:18:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232985AbjJQBSo (ORCPT ); Mon, 16 Oct 2023 21:18:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232096AbjJQBSm (ORCPT ); Mon, 16 Oct 2023 21:18:42 -0400 Received: from mail-ot1-x331.google.com (mail-ot1-x331.google.com [IPv6:2607:f8b0:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9717CA2 for ; Mon, 16 Oct 2023 18:18:41 -0700 (PDT) Received: by mail-ot1-x331.google.com with SMTP id 46e09a7af769-6c4c594c0eeso3509723a34.0 for ; Mon, 16 Oct 2023 18:18:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1697505521; x=1698110321; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:reply-to:message-id:date :subject:cc:to:from:from:to:cc:subject:date:message-id:reply-to; bh=8E2y54OTGlC4SszPQLmvr7ApnpGiyusAG53urqiJELY=; b=kMBcuqKynKKuLmAtvC1tF38zG1aD+steiWji/p7L5tduX+na25iP+vv2I9L9RArLhd bAfiGGI78B4Gmv0onPqU/Ho6g5BR0aJTNVdKYYuoNAepxBMmzExz9zp1d5tPLRLuG10P 6iGyvpFcz1zMJM9oSGaRBgW+gA4IPXmhXlLv6Nv7LIEKBrDXRV8oI0mvIZ92rd8LjwuS mLR/DLJMcFjoHOXhLHGaHopJ3E6K8xA1H4+k+tH6QTHNmEzt7xyIKPuUHw4lhAIwth3A ULt50qi7b6Aq4VOXrVJ7HTinQx2h/A8aRnOr+q78lfK1fZt1ekqcYgH8rs2x9D5OxIiQ /vzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697505521; x=1698110321; h=content-transfer-encoding:mime-version:reply-to:message-id:date :subject:cc:to:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=8E2y54OTGlC4SszPQLmvr7ApnpGiyusAG53urqiJELY=; b=FIOo1rYu/t7cfz9zp+JrTqu+Lsh6+H4Sk7bOkyLzor9aiYi/HUTlygHpljFx7OlVFG RqoIah37BzptrfHuHgNa2dXj+TgvzuMEhFZlwQLYEP9VrZniRo/JGfixpAcEy93p/vjI r/Y7R9dW+bxUBaJlkxL7WG34p9f0AerH4NhjjwTdMHmJezaZmpqUXL7RNnPWkyYBfeZI 7n4hKQcugjW7r5Uo7oYAPYKZpzZCjnpSsrvPYBagy+m8SQ6SwukWL1c8ZeJhxbFkgatL 9Z257dMKgeYvgA/MgQAneCl2mJtU5pLrZV51Tjq62fwMPHyyhb20HS3FW0ew83gv1CWK t8xQ== X-Gm-Message-State: AOJu0Yz0qHAfkGHfhjOTpY2h5OT/Kjn5QoFHmlOycm+Cjta9YSz3tes7 hlhF13/JzVXss7DgDjszEAv5ibJcQmLBk69O X-Google-Smtp-Source: AGHT+IH6NELBiIY7B0GJ4SFGNnXeKXcRCm9FRmr4KcEHGyr1Vn29uHDiZ6a7F8PJs3exhbdJrhL7zA== X-Received: by 2002:a05:6830:1e72:b0:6c4:e81f:59b8 with SMTP id m18-20020a0568301e7200b006c4e81f59b8mr851723otr.22.1697505520861; Mon, 16 Oct 2023 18:18:40 -0700 (PDT) Received: from KASONG-MB2.tencent.com ([103.7.29.31]) by smtp.gmail.com with ESMTPSA id y15-20020aa79aef000000b006926506de1csm191839pfp.28.2023.10.16.18.18.38 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 16 Oct 2023 18:18:40 -0700 (PDT) From: Kairui Song To: linux-mm@kvack.org Cc: Andrew Morton , "Huang, Ying" , linux-kernel@vger.kernel.org, Kairui Song Subject: [PATCH] mm/swap: avoid a xa load for swapout path Date: Tue, 17 Oct 2023 09:17:28 +0800 Message-ID: <20231017011728.37508-1-ryncsn@gmail.com> X-Mailer: git-send-email 2.42.0 Reply-To: Kairui Song MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Kairui Song A variable is never used for swapout path (shadowp is NULL) and compiler is unable to optimize out the unneeded load since it's a function call. Signed-off-by: Kairui Song Reviewed-by: Matthew Wilcox (Oracle) --- mm/swap_state.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index b3b14bd0dd64..ab79ffb71736 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -109,9 +109,9 @@ int add_to_swap_cache(struct folio *folio, swp_entry_t = entry, goto unlock; for (i =3D 0; i < nr; i++) { VM_BUG_ON_FOLIO(xas.xa_index !=3D idx + i, folio); - old =3D xas_load(&xas); - if (xa_is_value(old)) { - if (shadowp) + if (shadowp) { + old =3D xas_load(&xas); + if (xa_is_value(old)) *shadowp =3D old; } xas_store(&xas, folio); --=20 2.42.0