From patchwork Thu Oct 12 23:04:49 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuan-Wei Chiu X-Patchwork-Id: 13420218 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 48834CDB47E for ; Fri, 13 Oct 2023 07:18:58 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6EB4310E5A9; Fri, 13 Oct 2023 07:18:57 +0000 (UTC) Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by gabe.freedesktop.org (Postfix) with ESMTPS id 73EE610E580; Thu, 12 Oct 2023 23:04:57 +0000 (UTC) Received: by mail-pf1-x42e.google.com with SMTP id d2e1a72fcca58-690f8e63777so363727b3a.0; Thu, 12 Oct 2023 16:04:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1697151897; x=1697756697; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=MjY6Bfa7hXy3EtsVkBFJvcxDVqkLy8yAMFEk0tgy2ww=; b=g8WnTtjxQAwgvtFqp/Q1qtALSLH5i6giuXTSkj5QQxE09xTHxj1rBJZzpt79WZl7vM 9uXmwXN0cxpLHNlj0XdxNmcJDhL+pp9ZGFFd3mly2+3DXvQrRgV4++WgsjuEWQ9p0WXY uK0FDkLmFNa5LelNivHNn/yNbOGbkXpt7gg863YWYhic1PZSMK4PBLkbSkrW6xTRGlr2 9U/Y1Z5GQvS9kjrqq/CvHKUwwAJURDJP3QnTr+iQZIksvRPJ5igoOrRN3iAyKFNWCFHQ TmOBleT+Bg+/7gK/zGWmKAOTpLim7CvFEKQFAsHUeCvAbKRfjz9T2anA6tiezFgaypW7 u62w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697151897; x=1697756697; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=MjY6Bfa7hXy3EtsVkBFJvcxDVqkLy8yAMFEk0tgy2ww=; b=B2I/TajRFazx3TaN6/0oPSUNtwH3b3jGJT7dWCBt7Ku+duGVqLDAEisjAn4orkGJ8B D0pSvvql+mipHVmMde+oqNoM2cP85cmh58ungXmxebbViD1wLtw2XWd6OC+YtzFwRhd8 MSTO/JNvmzFIaZ5pUdzMbzg0ZjnJsqOFSQcw0bIA92Z7+wZoClMSixKsGJ+qgbBKyXKl twKMgFY+MxcUiGK6J/skiDOo9EyjwMThmt8/Oee+QlzjS7XNGUzm0OFPYKpp2pDuNxoN qzpRfWvJ+V06IV1XY9F4AZcXqnBUudUGdLX8SDAfo1sQrR3ZVzpglaM/6WGlXFlO9gzm H8Yw== X-Gm-Message-State: AOJu0YxGrWrRarcvT9dK85oXw/9J4XIwmcIvm+4K0ILysnR9LoCRNkfI aBzOGOobDvHyiaAXv0e82Ew= X-Google-Smtp-Source: AGHT+IH+4v5f93VcvRkHnnVgNR/Vyt3EU7gWUCAaBPEj/wJkDgmWUDn2+fSuZCy+1+14UNBZQ7kIzw== X-Received: by 2002:a05:6a00:2e92:b0:692:b3d4:e6c3 with SMTP id fd18-20020a056a002e9200b00692b3d4e6c3mr27619108pfb.0.1697151896807; Thu, 12 Oct 2023 16:04:56 -0700 (PDT) Received: from localhost.localdomain ([140.116.154.65]) by smtp.gmail.com with ESMTPSA id e4-20020a62ee04000000b006889664aa6csm12193998pfi.5.2023.10.12.16.04.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Oct 2023 16:04:55 -0700 (PDT) From: Kuan-Wei Chiu To: zhenyuw@linux.intel.com, zhi.a.wang@intel.com Subject: [PATCH] drm/i915/gvt: Optimize mmio_offset_compare() for efficiency Date: Fri, 13 Oct 2023 07:04:49 +0800 Message-Id: <20231012230449.2109078-1-visitorckw@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Mailman-Approved-At: Fri, 13 Oct 2023 07:18:56 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tvrtko.ursulin@linux.intel.com, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, Kuan-Wei Chiu , dri-devel@lists.freedesktop.org, rodrigo.vivi@intel.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" The original code used conditional branching in the mmio_offset_compare function to compare two values and return -1, 1, or 0 based on the result. However, the list_sort comparison function only needs results <0, >0, or =0. This patch optimizes the code to make the comparison branchless, improving efficiency and reducing code size. This change reduces the number of comparison operations from 1-2 to a single subtraction operation, thereby saving the number of instructions. Signed-off-by: Kuan-Wei Chiu --- drivers/gpu/drm/i915/gvt/debugfs.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/gvt/debugfs.c b/drivers/gpu/drm/i915/gvt/debugfs.c index baccbf1761b7..998d82a259c8 100644 --- a/drivers/gpu/drm/i915/gvt/debugfs.c +++ b/drivers/gpu/drm/i915/gvt/debugfs.c @@ -48,11 +48,7 @@ static int mmio_offset_compare(void *priv, ma = container_of(a, struct diff_mmio, node); mb = container_of(b, struct diff_mmio, node); - if (ma->offset < mb->offset) - return -1; - else if (ma->offset > mb->offset) - return 1; - return 0; + return ma->offset - mb->offset; } static inline int mmio_diff_handler(struct intel_gvt *gvt,