From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f69.google.com (mail-oi0-f69.google.com [209.85.218.69]) by kanga.kvack.org (Postfix) with ESMTP id 30C1D6B0069 for ; Fri, 9 Sep 2016 11:40:31 -0400 (EDT) Received: by mail-oi0-f69.google.com with SMTP id w193so193820837oiw.2 for ; Fri, 09 Sep 2016 08:40:31 -0700 (PDT) Received: from mail-it0-x234.google.com (mail-it0-x234.google.com. [2607:f8b0:4001:c0b::234]) by mx.google.com with ESMTPS id v84si5068125iod.190.2016.09.09.08.40.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Sep 2016 08:40:30 -0700 (PDT) Received: by mail-it0-x234.google.com with SMTP id c198so19647819ith.1 for ; Fri, 09 Sep 2016 08:40:30 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <5d5ef209-e005-12c6-9b34-1fdd21e1e6e2@linux.intel.com> References: <20160908225636.GB15167@linux.intel.com> <5d5ef209-e005-12c6-9b34-1fdd21e1e6e2@linux.intel.com> From: Dan Williams Date: Fri, 9 Sep 2016 08:40:29 -0700 Message-ID: Subject: Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in /proc/self/smaps) Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Xiao Guangrong Cc: Ross Zwisler , Dave Hansen , Paolo Bonzini , Andrew Morton , Michal Hocko , Gleb Natapov , mtosatti@redhat.com, KVM list , "linux-kernel@vger.kernel.org" , Stefan Hajnoczi , Yumei Huang , Linux MM , "linux-nvdimm@lists.01.org" , linux-fsdevel On Fri, Sep 9, 2016 at 1:55 AM, Xiao Guangrong wrote: [..] >> >> Whether a persistent memory mapping requires an msync/fsync is a >> filesystem specific question. This mincore proposal is separate from >> that. Consider device-DAX for volatile memory or mincore() called on >> an anonymous memory range. In those cases persistence and filesystem >> metadata are not in the picture, but it would still be useful for >> userspace to know "is there page cache backing this mapping?" or "what >> is the TLB geometry of this mapping?". > > > I got a question about msync/fsync which is beyond the topic of this thread > :) > > Whether msync/fsync can make data persistent depends on ADR feature on > memory > controller, if it exists everything works well, otherwise, we need to have > another > interface that is why 'Flush hint table' in ACPI comes in. 'Flush hint > table' is > particularly useful for nvdimm virtualization if we use normal memory to > emulate > nvdimm with data persistent characteristic (the data will be flushed to a > persistent storage, e.g, disk). > > Does current PMEM programming model fully supports 'Flush hint table'? Is > userspace allowed to use these addresses? If you publish flush hint addresses in the virtual NFIT the guest VM will write to them whenever a REQ_FLUSH or REQ_FUA request is sent to the virtual /dev/pmemX device. Yes, seems straightforward to take a VM exit on those events and flush simulated pmem to persistent storage. -- 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