From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id A1B886B072F for ; Fri, 4 Aug 2017 04:52:41 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id r13so11235003pfd.14 for ; Fri, 04 Aug 2017 01:52:41 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTPS id 3si818152plt.612.2017.08.04.01.52.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 04 Aug 2017 01:52:40 -0700 (PDT) Message-ID: <5984367A.3030809@intel.com> Date: Fri, 04 Aug 2017 16:55:22 +0800 From: Wei Wang MIME-Version: 1.0 Subject: Re: [PATCH v13 4/5] mm: support reporting free page blocks References: <59830897.2060203@intel.com> <20170803112831.GN12521@dhcp22.suse.cz> <5983130E.2070806@intel.com> <20170803124106.GR12521@dhcp22.suse.cz> <59832265.1040805@intel.com> <20170803135047.GV12521@dhcp22.suse.cz> <286AC319A985734F985F78AFA26841F73928C971@shsmsx102.ccr.corp.intel.com> <20170804000043-mutt-send-email-mst@kernel.org> <20170804075337.GC26029@dhcp22.suse.cz> <59842D1C.5020608@intel.com> <20170804082423.GG26029@dhcp22.suse.cz> In-Reply-To: <20170804082423.GG26029@dhcp22.suse.cz> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: "Michael S. Tsirkin" , "linux-kernel@vger.kernel.org" , "virtualization@lists.linux-foundation.org" , "kvm@vger.kernel.org" , "linux-mm@kvack.org" , "mawilcox@microsoft.com" , "akpm@linux-foundation.org" , "virtio-dev@lists.oasis-open.org" , "david@redhat.com" , "cornelia.huck@de.ibm.com" , "mgorman@techsingularity.net" , "aarcange@redhat.com" , "amit.shah@redhat.com" , "pbonzini@redhat.com" , "liliang.opensource@gmail.com" , "yang.zhang.wz@gmail.com" , "quan.xu@aliyun.com" On 08/04/2017 04:24 PM, Michal Hocko wrote: > >> For our use case, the callback just puts the reported page >> block to the ring, then returns. If the ring is full as the host >> is busy, then I think it should skip this one, and just return. >> Because: >> A. This is an optimization feature, losing a couple of free >> pages to report isn't that important; >> B. In reality, I think it's uncommon to see this ring getting >> full (I didn't observe ring full in the tests), since the host >> (consumer) is notified to take out the page block right >> after it is added. > I thought you only updated a pre allocated bitmat... Anyway, I cannot > comment on this part much as I am not familiar with your usecase. > Actually the bitmap is in the hypervisor (host). The callback puts the (pfn,size) on a ring which is shared with the hypervisor, then the hypervisor takes that info from the ring and updates that bitmap. Best, Wei -- 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