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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 CF828C07E9B for ; Wed, 7 Jul 2021 07:15:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB8A861CA8 for ; Wed, 7 Jul 2021 07:15:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230356AbhGGHSC (ORCPT ); Wed, 7 Jul 2021 03:18:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230312AbhGGHSB (ORCPT ); Wed, 7 Jul 2021 03:18:01 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0605CC061574; Wed, 7 Jul 2021 00:15:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=qgP4dqrgrNAWWYzN10vwwnL4jCkYS3ZFGuIkGEq6E6Q=; b=gtmh+CfiK9rsRm6VYrmNHuTvRm ARTQH0d1hYpQuDRcfmJgPi44o72pVtbs+wBK4UE1cq6IUzBnP1jr6fPRczUxDcfb6jNck4axxz90/ L3/U9JouDFpeORcCICMtvyBmnvMsiCh6W4YyffyqahvDhc1HpBe1+/JuVvNVvGeGHB2IWmJr/7Ss+ 9V4waSHitW/XIWmSxAuhX7zNiZGlX26gIscWK6nnwKn/tHakF+xcXYOiOvPzpElSyp//yDog33hS0 4rga9++ADk+dZkdfiEW0jf4QKum0GChNKiySl4V7/VVU5tb9VvGgreZOjT4gZ/aDXeyPyFqG4owXD e/hN2ZbQ==; Received: from hch by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m11lX-00C9Tz-Ir; Wed, 07 Jul 2021 07:14:43 +0000 Date: Wed, 7 Jul 2021 08:14:39 +0100 From: Christoph Hellwig To: Christian K??nig Cc: Christoph Hellwig , John Stultz , lkml , Daniel Vetter , Sumit Semwal , Liam Mark , Chris Goldsworthy , Laura Abbott , Brian Starkey , Hridya Valsaraju , Suren Baghdasaryan , Sandeep Patil , Daniel Mentz , ??rjan Eide , Robin Murphy , Ezequiel Garcia , Simon Ser , James Jones , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, Mel Gorman , linux-mm@kvack.org Subject: Re: page pools, was Re: [PATCH v9 1/5] drm: Add a sharable drm page-pool implementation Message-ID: References: <20210630013421.735092-1-john.stultz@linaro.org> <20210630013421.735092-2-john.stultz@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 07, 2021 at 09:10:26AM +0200, Christian K??nig wrote: > Well, the original code all this is based on already had the comment that > this really belong into the page allocator. > > The key point is traditionally only GPUs used uncached and write-combined > memory in such large quantities that having a pool for them makes sense. > > Because of this we had this separately to reduce the complexity in the page > allocator to handle another set of complexity of allocation types. > > For the upside, for those use cases it means huge performance improvements > for those drivers. See the numbers John provided in the cover letter. > > But essentially at least I would be totally fine moving this into the page > allocator, but moving it outside of TTM already helps with this goal. So > this patch set is certainly a step into the right direction. Unless I'm badly misreading the patch and this series there is nothing about cache attributes in this code. It just allocates pages, zeroes them, eventually hands them out to a consumer and registers a shrinker for its freelist. If OTOH it actually dealt with cachability that should be documented in the commit log and probably also the naming of the implementation.