From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f70.google.com (mail-vk0-f70.google.com [209.85.213.70]) by kanga.kvack.org (Postfix) with ESMTP id B9CB36B02C4 for ; Thu, 4 May 2017 11:49:48 -0400 (EDT) Received: by mail-vk0-f70.google.com with SMTP id 5so72538vkj.7 for ; Thu, 04 May 2017 08:49:48 -0700 (PDT) Received: from gate.crashing.org (gate.crashing.org. [63.228.1.57]) by mx.google.com with ESMTPS id y64si1151701vkc.128.2017.05.04.08.49.46 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 04 May 2017 08:49:47 -0700 (PDT) Message-ID: <1493912961.25766.379.camel@kernel.crashing.org> Subject: Re: [RFC 0/4] RFC - Coherent Device Memory (Not for inclusion) From: Benjamin Herrenschmidt Date: Thu, 04 May 2017 17:49:21 +0200 In-Reply-To: <20170504125250.GH31540@dhcp22.suse.cz> References: <20170419075242.29929-1-bsingharora@gmail.com> <20170502143608.GM14593@dhcp22.suse.cz> <1493875615.7934.1.camel@gmail.com> <20170504125250.GH31540@dhcp22.suse.cz> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Balbir Singh Cc: linux-mm@kvack.org, akpm@linux-foundation.org, khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com, srikar@linux.vnet.ibm.com, haren@linux.vnet.ibm.com, jglisse@redhat.com, mgorman@techsingularity.net, arbab@linux.vnet.ibm.com, vbabka@suse.cz, cl@linux.com On Thu, 2017-05-04 at 14:52 +0200, Michal Hocko wrote: > But the direct reclaim would be effective only _after_ all other nodes > are full. > > I thought that kswapd reclaim is a problem because the HW doesn't > support aging properly but as the direct reclaim works then what is the > actual problem? Ageing isn't isn't completely broken. The ATS MMU supports dirty/accessed just fine. However the TLB invalidations are quite expensive with a GPU so too much harvesting is detrimental, and the GPU tends to check pages out using a special "read with intend to write" mode, which means it almost always set the dirty bit if the page is writable to begin with. Cheers, Ben. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org