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 X-Spam-Level: X-Spam-Status: No, score=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=no 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 B5351C35242 for ; Fri, 24 Jan 2020 09:09:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6AC422071A for ; Fri, 24 Jan 2020 09:09:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=shipmail.org header.i=@shipmail.org header.b="i5yiCugO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6AC422071A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=shipmail.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D16606B02BD; Fri, 24 Jan 2020 04:09:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C78836B02C1; Fri, 24 Jan 2020 04:09:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9B8C56B02C0; Fri, 24 Jan 2020 04:09:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0049.hostedemail.com [216.40.44.49]) by kanga.kvack.org (Postfix) with ESMTP id 798506B02BC for ; Fri, 24 Jan 2020 04:09:55 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 33FD4181AEF09 for ; Fri, 24 Jan 2020 09:09:55 +0000 (UTC) X-FDA: 76411955550.10.debt94_908eaf6790c5b X-HE-Tag: debt94_908eaf6790c5b X-Filterd-Recvd-Size: 6579 Received: from pio-pvt-msa2.bahnhof.se (pio-pvt-msa2.bahnhof.se [79.136.2.41]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Fri, 24 Jan 2020 09:09:53 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by pio-pvt-msa2.bahnhof.se (Postfix) with ESMTP id 7CDD93F684; Fri, 24 Jan 2020 10:09:51 +0100 (CET) Authentication-Results: pio-pvt-msa2.bahnhof.se; dkim=pass (1024-bit key; unprotected) header.d=shipmail.org header.i=@shipmail.org header.b=i5yiCugO; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at bahnhof.se Received: from pio-pvt-msa2.bahnhof.se ([127.0.0.1]) by localhost (pio-pvt-msa2.bahnhof.se [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id u1YBJXFKoo1R; Fri, 24 Jan 2020 10:09:50 +0100 (CET) Received: from mail1.shipmail.org (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) (Authenticated sender: mb878879) by pio-pvt-msa2.bahnhof.se (Postfix) with ESMTPA id 52E243F516; Fri, 24 Jan 2020 10:09:47 +0100 (CET) Received: from localhost.localdomain.localdomain (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) by mail1.shipmail.org (Postfix) with ESMTPSA id 7EAEA360315; Fri, 24 Jan 2020 10:09:47 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=shipmail.org; s=mail; t=1579856987; bh=0OBWc+qrG3n91MjpvfCc4sv/PlYdJ5/g79jyfk6lzSM=; h=From:To:Cc:Subject:Date:From; b=i5yiCugOnURnUfwxXoml+vC8KrAuHBqALjXrKfBL6xCveEYyjITWuQRxaJYvu8L0A Wb5nmLEGGWH56i98QuEKwVhOJ6LV2Q8q3qaQrI8GoHddItsN8PzYhqHu0PWmXNE+VY 1qGSFFk+ufpSEXCQ09EaEq4+bUZWYTg3hrKYJQQg= From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m=20=28VMware=29?= To: linux-mm@kvack.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: pv-drivers@vmware.com, linux-graphics-maintainer@vmware.com, =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= , Andrew Morton , Michal Hocko , "Matthew Wilcox (Oracle)" , "Kirill A. Shutemov" , Ralph Campbell , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , =?UTF-8?q?Christian=20K=C3=B6nig?= , Dan Williams Subject: [PATCH v2 0/9] Huge page-table entries for TTM Date: Fri, 24 Jan 2020 10:09:31 +0100 Message-Id: <20200124090940.26571-1-thomas_os@shipmail.org> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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: In order to reduce TLB misses and CPU usage this patchset enables huge- and giant page-table entries for TTM and TTM-enabled graphics drivers. Patch 1 and 2 introduce a vma_is_special_huge() function to make the mm c= ode take the same path as DAX when splitting huge- and giant page table entri= es, (which currently means zapping the page-table entry and rely on re-faulti= ng). Patch 3 makes the mm code split existing huge page-table entries on huge_fault fallbacks. Typically on COW or on buffer-objects that want write-notify. COW and write-notification is always done on the lowest page-table level. See the patch log message for additional considerations= . Patch 4 introduces functions to allow the graphics drivers to manipulate the caching- and encryption flags of huge page-table entries without ugly hacks. Patch 5 implements the huge_fault handler in TTM. This enables huge page-table entries, provided that the kernel is configu= red to support transhuge pages, either by default or using madvise(). However, they are unlikely to be inserted unless the kernel buffer object pfns and user-space addresses align perfectly. There are various options here, but since buffer objects that reside in system pages typically star= t at huge page boundaries if they are backed by huge pages, we try to enfor= ce buffer object starting pfns and user-space addresses to be huge page-size aligned if their size exceeds a huge page-size. If pud-size transhuge ("giant") pages are enabled by the arch, the same holds for those. Patch 6 implements a specialized huge_fault handler for vmwgfx. The vmwgfx driver may perform dirty-tracking and needs some special code to handle that correctly. Patch 7 implements a drm helper to align user-space addresses according to the above scheme, if possible. Patch 8 implements a TTM range manager for vmwgfx that does the same for graphics IO memory. This may later be reused by other graphics drivers if necessary. Patch 9 finally hooks up the helpers of patch 7 and 8 to the vmwgfx drive= r. A similar change is needed for graphics drivers that want a reasonable likelyhood of actually using huge page-table entries. If a buffer object size is not huge-page or giant-page aligned, its size will NOT be inflated by this patchset. This means that the buffe= r object tail will use smaller size page-table entries and thus no memory overhead occurs. Drivers that want to pay the memory overhead price need = to implement their own scheme to inflate buffer-object sizes. PMD size huge page-table-entries have been tested with vmwgfx and found t= o work well both with system memory backed and IO memory backed buffer obje= cts. PUD size giant page-table-entries have seen limited (fault and COW) testi= ng using a modified kernel (to support 1GB page allocations) and a fake vmwg= fx TTM memory type. The vmwgfx driver does otherwise not support 1GB-size IO memory resources. Comments and suggestions welcome. Thomas Changes since RFC: * Check for buffer objects present in contigous IO Memory (Christian K=C3= =B6nig) * Rebased on the vmwgfx emulated coherent memory functionality. That reba= se adds patch 5. Changes since v1: * Make the new TTM range manager vmwgfx-specific. (Christian K=C3=B6nig) * Minor fixes for configs that don't support or only partially support transhuge pages. Cc: Andrew Morton Cc: Michal Hocko Cc: "Matthew Wilcox (Oracle)" Cc: "Kirill A. Shutemov" Cc: Ralph Campbell Cc: "J=C3=A9r=C3=B4me Glisse" Cc: "Christian K=C3=B6nig" Cc: Dan Williams