From patchwork Mon Apr 17 10:38:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Fabio M. De Francesco" X-Patchwork-Id: 13213682 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 17896C77B70 for ; Mon, 17 Apr 2023 10:39:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 21BDB10E401; Mon, 17 Apr 2023 10:39:11 +0000 (UTC) Received: from mail-wm1-x330.google.com (mail-wm1-x330.google.com [IPv6:2a00:1450:4864:20::330]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9D9F410E3F9; Mon, 17 Apr 2023 10:39:06 +0000 (UTC) Received: by mail-wm1-x330.google.com with SMTP id o9-20020a05600c510900b003f17012276fso2000813wms.4; Mon, 17 Apr 2023 03:39:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1681727944; x=1684319944; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=dAW7sB6+Z5ZOltjkFBMt2NbhGjStc/CgCoci8oN9nks=; b=lk90wuKk7kR9IX6uMik68yOAyW5/zZmQWcphsp7dCp9z3gtp/owgQL9h2aAbLKBZl4 fCT8G5zvkCrwE8UQwr3TI2qV7TEBSeuZSe9ChabtOXCucPLOySit4w+Ukcnt1MR6xcJD RBcU0cLyIawG1B8WldS9XwJKzvAn1uvF3XJQUQD4rxY6QsnOGA8yokADx7cMlcSkaxFs 5+cWcTxbRQ//yFlyW01nwMQQHtlmblF6pwjWClW/urNU4TC+6JZnbE5L8Bg4kfHflzxL /4UrOEAQM7KKog1/7dO7jGRKmFaB5tY3maCKiDRQFq5G039Z4m4zDMRjCuuJMMI16nKs eHFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681727944; x=1684319944; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=dAW7sB6+Z5ZOltjkFBMt2NbhGjStc/CgCoci8oN9nks=; b=LEaif8lI7lzBo4o5EVUxTFKfCplzJ081X2qKqr9/eNXBF5rpSyPAsE665KKsEqrUAX yYP+wW0pXkRzQfan8+z+nVvjWb7A67nJDeELWR/s8P09CuTWQn7w0R+I2/dMzSn1muwy xyUFBTFDwVP0cHAURN9mTsqJCryMFdoKJEjkVKv5267QmSqosfXPkrGWzU2iWDBO9ODj k8LUkCftrOObPdCMlLfv8ctQapIE3egoROZlPvFc3T9xcpJaY6K2VrDHZY2ImxJ8txCA +pFm4MzLg2Gug1jS3ts1Phe3+eY56MER6BsqzOZpq4FMpz1/UpBT7Dx/mAQcvesN4V6m FmfA== X-Gm-Message-State: AAQBX9f3J0PoJdKcob2wekRx1kKOxVn9SzmilZomRueXYWxGNpvo8q3D kksYf+EjctnmrhRo/ZzQhOE= X-Google-Smtp-Source: AKy350bqJ/bHsDjtLWvuVfbc6Uq/QInCoRKCm+KLyl/hHEccIaE3q+1++wO1znNLhcQOGVkqIM5BVw== X-Received: by 2002:a05:600c:4f46:b0:3f1:7443:6d6e with SMTP id m6-20020a05600c4f4600b003f174436d6emr1590807wmq.19.1681727943960; Mon, 17 Apr 2023 03:39:03 -0700 (PDT) Received: from localhost.localdomain (host-87-19-108-254.retail.telecomitalia.it. [87.19.108.254]) by smtp.gmail.com with ESMTPSA id y12-20020a5d470c000000b002c70ce264bfsm10238018wrq.76.2023.04.17.03.39.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Apr 2023 03:39:03 -0700 (PDT) From: "Fabio M. De Francesco" To: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Daniel Vetter , Matt Roper , John Harrison , Daniele Ceraolo Spurio , Chris Wilson , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Date: Mon, 17 Apr 2023 12:38:53 +0200 Message-Id: <20230417103854.23333-3-fmdefrancesco@gmail.com> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230417103854.23333-1-fmdefrancesco@gmail.com> References: <20230417103854.23333-1-fmdefrancesco@gmail.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH v2 2/3] drm/i915/gt: Replace kmap() with kmap_local_page() X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ira Weiny , "Fabio M. De Francesco" Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" kmap() s been deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap’s pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and are still valid. Obviously, thread locality implies that the kernel virtual addresses are only valid in the context of the callers. The use of kmap_local_page() in i915/gt doesn't break the above-mentioned constraint, so it should be preferred to kmap(). Therefore, replace kmap() with kmap_local_page() in i915/gt. Suggested-by: Ira Weiny Signed-off-by: Fabio M. De Francesco --- drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c | 4 ++-- drivers/gpu/drm/i915/gt/shmem_utils.c | 11 ++++------- 2 files changed, 6 insertions(+), 9 deletions(-) -- 2.40.0 diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c b/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c index 37d0b0fe791d..89295c6921d6 100644 --- a/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c +++ b/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c @@ -749,7 +749,7 @@ static void swizzle_page(struct page *page) char *vaddr; int i; - vaddr = kmap(page); + vaddr = kmap_local_page(page); for (i = 0; i < PAGE_SIZE; i += 128) { memcpy(temp, &vaddr[i], 64); @@ -757,7 +757,7 @@ static void swizzle_page(struct page *page) memcpy(&vaddr[i + 64], temp, 64); } - kunmap(page); + kunmap_local(vaddr); } /** diff --git a/drivers/gpu/drm/i915/gt/shmem_utils.c b/drivers/gpu/drm/i915/gt/shmem_utils.c index 449c9ed44382..be809839a241 100644 --- a/drivers/gpu/drm/i915/gt/shmem_utils.c +++ b/drivers/gpu/drm/i915/gt/shmem_utils.c @@ -101,22 +101,19 @@ static int __shmem_rw(struct file *file, loff_t off, unsigned int this = min_t(size_t, PAGE_SIZE - offset_in_page(off), len); struct page *page; - void *vaddr; page = shmem_read_mapping_page_gfp(file->f_mapping, pfn, GFP_KERNEL); if (IS_ERR(page)) return PTR_ERR(page); - vaddr = kmap(page); if (write) { - memcpy(vaddr + offset_in_page(off), ptr, this); + memcpy_to_page(page, offset_in_page(off), ptr, this); set_page_dirty(page); } else { - memcpy(ptr, vaddr + offset_in_page(off), this); + memcpy_from_page(ptr, page, offset_in_page(off), this); } mark_page_accessed(page); - kunmap(page); put_page(page); len -= this; @@ -143,11 +140,11 @@ int shmem_read_to_iosys_map(struct file *file, loff_t off, if (IS_ERR(page)) return PTR_ERR(page); - vaddr = kmap(page); + vaddr = kmap_local_page(page); iosys_map_memcpy_to(map, map_off, vaddr + offset_in_page(off), this); mark_page_accessed(page); - kunmap(page); + kunmap_local(vaddr); put_page(page); len -= this;