Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932730AbcLAOLa (ORCPT ); Thu, 1 Dec 2016 09:11:30 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:33708 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932618AbcLAOL2 (ORCPT ); Thu, 1 Dec 2016 09:11:28 -0500 Date: Thu, 1 Dec 2016 15:11:25 +0100 From: Michal Hocko To: Vlastimil Babka Cc: "Robin H. Johnson" , Michal Nazarewicz , linux-kernel@vger.kernel.org, linux-mm@kvack.org, dri-devel@lists.freedesktop.org, Joonsoo Kim , Marek Szyprowski Subject: Re: drm/radeon spamming alloc_contig_range: [xxx, yyy) PFNs busy busy Message-ID: <20161201141125.GB20966@dhcp22.suse.cz> References: <20161130092239.GD18437@dhcp22.suse.cz> <20161130132848.GG18432@dhcp22.suse.cz> <20161201071507.GC18272@dhcp22.suse.cz> <20161201072119.GD18272@dhcp22.suse.cz> <9f2aa4e4-d7d5-e24f-112e-a4b43f0a0ccc@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9f2aa4e4-d7d5-e24f-112e-a4b43f0a0ccc@suse.cz> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1027 Lines: 26 Let's also CC Marek On Thu 01-12-16 08:43:40, Vlastimil Babka wrote: > On 12/01/2016 08:21 AM, Michal Hocko wrote: > > Forgot to CC Joonsoo. The email thread starts more or less here > > http://lkml.kernel.org/r/20161130092239.GD18437@dhcp22.suse.cz > > > > On Thu 01-12-16 08:15:07, Michal Hocko wrote: > > > On Wed 30-11-16 20:19:03, Robin H. Johnson wrote: > > > [...] > > > > alloc_contig_range: [83f2a3, 83f2a4) PFNs busy > > > > > > Huh, do I get it right that the request was for a _single_ page? Why do > > > we need CMA for that? > > Ugh, good point. I assumed that was just the PFNs that it failed to migrate > away, but it seems that's indeed the whole requested range. Yeah sounds some > part of the dma-cma chain could be smarter and attempt CMA only for e.g. > costly orders. Is there any reason why the DMA api doesn't try the page allocator first before falling back to the CMA? I simply have a hard time to see why the CMA should be used (and fragment) for small requests size. -- Michal Hocko SUSE Labs