From patchwork Thu Jul 29 13:34:20 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tvrtko Ursulin X-Patchwork-Id: 12408747 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,HK_RANDOM_FROM,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 351C8C432BE for ; Thu, 29 Jul 2021 13:34:40 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id ECC2060F23 for ; Thu, 29 Jul 2021 13:34:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org ECC2060F23 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 679D86EDA9; Thu, 29 Jul 2021 13:34:36 +0000 (UTC) Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by gabe.freedesktop.org (Postfix) with ESMTPS id 834596ECAB; Thu, 29 Jul 2021 13:34:33 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10059"; a="209769972" X-IronPort-AV: E=Sophos;i="5.84,278,1620716400"; d="scan'208";a="209769972" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2021 06:34:33 -0700 X-IronPort-AV: E=Sophos;i="5.84,278,1620716400"; d="scan'208";a="438420097" Received: from eoghanru-mobl.ger.corp.intel.com (HELO tursulin-mobl2.home) ([10.213.215.170]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2021 06:34:30 -0700 From: Tvrtko Ursulin To: Intel-gfx@lists.freedesktop.org Subject: [PATCH 2/2] drm/i915: Use Transparent Hugepages when IOMMU is enabled Date: Thu, 29 Jul 2021 14:34:20 +0100 Message-Id: <20210729133420.770672-2-tvrtko.ursulin@linux.intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210729133420.770672-1-tvrtko.ursulin@linux.intel.com> References: <20210729133420.770672-1-tvrtko.ursulin@linux.intel.com> MIME-Version: 1.0 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 , Eero Tamminen , dri-devel@lists.freedesktop.org, Chris Wilson , Matthew Auld , Rodrigo Vivi Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Tvrtko Ursulin Usage of Transparent Hugepages was disabled in 9987da4b5dcf ("drm/i915: Disable THP until we have a GPU read BW W/A"), but since it appears majority of performance regressions reported with an enabled IOMMU can be almost eliminated by turning them on, lets just do that. To err on the side of safety we keep the current default in cases where IOMMU is not active, and only when it is default to the "huge=within_size" mode. Although there probably would be wins to enable them throughout, more extensive testing across benchmarks and platforms would need to be done. With the patch and IOMMU enabled my local testing on a small Skylake part shows OglVSTangent regression being reduced from ~14% (IOMMU on versus IOMMU off) to ~2% (same comparison but with THP on). v2: * Add Kconfig dependency to transparent hugepages and some help text. * Move to helper for easier handling of kernel build options. v3: * Drop Kconfig. (Daniel) References: b901bb89324a ("drm/i915/gemfs: enable THP") References: 9987da4b5dcf ("drm/i915: Disable THP until we have a GPU read BW W/A") References: https://gitlab.freedesktop.org/drm/intel/-/issues/430 Co-developed-by: Chris Wilson Signed-off-by: Chris Wilson Cc: Joonas Lahtinen Cc: Matthew Auld Cc: Eero Tamminen Cc: Tvrtko Ursulin Cc: Rodrigo Vivi Cc: Daniel Vetter Signed-off-by: Tvrtko Ursulin Reviewed-by: Rodrigo Vivi # v1 --- drivers/gpu/drm/i915/gem/i915_gemfs.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gemfs.c b/drivers/gpu/drm/i915/gem/i915_gemfs.c index 5e6e8c91ab38..dbdbdc344d87 100644 --- a/drivers/gpu/drm/i915/gem/i915_gemfs.c +++ b/drivers/gpu/drm/i915/gem/i915_gemfs.c @@ -6,7 +6,6 @@ #include #include -#include #include "i915_drv.h" #include "i915_gemfs.h" @@ -15,6 +14,7 @@ int i915_gemfs_init(struct drm_i915_private *i915) { struct file_system_type *type; struct vfsmount *gemfs; + char *opts; type = get_fs_type("tmpfs"); if (!type) @@ -26,10 +26,26 @@ int i915_gemfs_init(struct drm_i915_private *i915) * * One example, although it is probably better with a per-file * control, is selecting huge page allocations ("huge=within_size"). - * Currently unused due to bandwidth issues (slow reads) on Broadwell+. + * However, we only do so to offset the overhead of iommu lookups + * due to bandwidth issues (slow reads) on Broadwell+. */ - gemfs = kern_mount(type); + opts = NULL; + if (intel_vtd_active()) { + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { + static char huge_opt[] = "huge=within_size"; /* r/w */ + + opts = huge_opt; + drm_info(&i915->drm, + "Transparent Hugepage mode '%s'\n", + opts); + } else { + drm_notice(&i915->drm, + "Transparent Hugepage support is recommended for optimal performance when IOMMU is enabled!\n"); + } + } + + gemfs = vfs_kern_mount(type, SB_KERNMOUNT, type->name, opts); if (IS_ERR(gemfs)) return PTR_ERR(gemfs);