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From: Matthew Wilcox <mawilcox@microsoft.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
	Brian Boylston <brian.boylston@hpe.com>,
	Tony Luck <tony.luck@intel.com>, Jan Kara <jack@suse.cz>,
	Toshi Kani <toshi.kani@hpe.com>,
	Mike Snitzer <snitzer@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>, Jeff Moyer <jmoyer@redhat.com>,
	Jens Axboe <axboe@fb.com>,
	"dm-devel@redhat.com" <dm-devel@redhat.com>,
	Ingo Molnar <mingo@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: RE: [PATCH 00/13] dax, pmem: move cpu cache maintenance to     libnvdimm
Date: Sun, 22 Jan 2017 18:19:24 +0000	[thread overview]
Message-ID: <BY2PR21MB00368E95CBB533D4C761C882CB730@BY2PR21MB0036.namprd21.prod.outlook.com> (raw)
In-Reply-To: <20170122162910.GA5267@lst.de>

From: Christoph Hellwig [mailto:hch@lst.de]
> On Sun, Jan 22, 2017 at 03:43:09PM +0000, Matthew Wilcox wrote:
> > In the case of a network filesystem being used to communicate with
> > a different VM on the same physical machine, there is no backing
> > device, just a network protocol.
> 
> Again, do you mean block device?  For a filesystem that does not do any
> pagecache writeback we already don't need a backing device, so I don't
> really see an issue there to start with.

No, I mean a network filesystem like 9p or cifs or nfs.  If the memcpy is supposed to be performed by the backing device and there is no backing device, then it's going to need to be done by the network filesystem.

(Also, the network filesystem might have a command, like RDMA has/will have, to ensure that the write has reached persistence)

WARNING: multiple messages have this Message-ID (diff)
From: Matthew Wilcox <mawilcox@microsoft.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
	Brian Boylston <brian.boylston@hpe.com>,
	"Tony Luck" <tony.luck@intel.com>, Jan Kara <jack@suse.cz>,
	Toshi Kani <toshi.kani@hpe.com>,
	Mike Snitzer <snitzer@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>, Jeff Moyer <jmoyer@redhat.com>,
	Jens Axboe <axboe@fb.com>,
	"dm-devel@redhat.com" <dm-devel@redhat.com>,
	Ingo Molnar <mingo@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: RE: [PATCH 00/13] dax, pmem: move cpu cache maintenance to     libnvdimm
Date: Sun, 22 Jan 2017 18:19:24 +0000	[thread overview]
Message-ID: <BY2PR21MB00368E95CBB533D4C761C882CB730@BY2PR21MB0036.namprd21.prod.outlook.com> (raw)
In-Reply-To: <20170122162910.GA5267@lst.de>

From: Christoph Hellwig [mailto:hch@lst.de]
> On Sun, Jan 22, 2017 at 03:43:09PM +0000, Matthew Wilcox wrote:
> > In the case of a network filesystem being used to communicate with
> > a different VM on the same physical machine, there is no backing
> > device, just a network protocol.
> 
> Again, do you mean block device?  For a filesystem that does not do any
> pagecache writeback we already don't need a backing device, so I don't
> really see an issue there to start with.

No, I mean a network filesystem like 9p or cifs or nfs.  If the memcpy is supposed to be performed by the backing device and there is no backing device, then it's going to need to be done by the network filesystem.

(Also, the network filesystem might have a command, like RDMA has/will have, to ensure that the write has reached persistence)

  reply	other threads:[~2017-01-22 18:19 UTC|newest]

Thread overview: 126+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-20  3:50 [PATCH 00/13] dax, pmem: move cpu cache maintenance to libnvdimm Dan Williams
2017-01-20  3:50 ` Dan Williams
2017-01-20  3:50 ` Dan Williams
2017-01-20  3:50 ` Dan Williams
2017-01-20  3:50 ` [PATCH 01/13] x86, dax, pmem: remove indirection around memcpy_from_pmem() Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50 ` [PATCH 02/13] block, dax: introduce dax_operations Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20 17:28   ` Dan Williams
2017-01-20 17:28     ` Dan Williams
2017-01-20 17:28     ` Dan Williams
2017-01-20 17:28     ` Dan Williams
2017-01-20  3:50 ` [PATCH 03/13] x86, dax, pmem: introduce 'copy_from_iter' dax operation Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-02-03  1:52   ` [lkp-robot] [x86, dax, pmem] 2e12109d1c: fio.write_bw_MBps -75% regression kernel test robot
2017-02-03  1:52     ` kernel test robot
2017-02-03  1:52     ` kernel test robot
2017-02-03  1:52     ` kernel test robot
2017-02-17  3:52   ` [PATCH 03/13] x86, dax, pmem: introduce 'copy_from_iter' dax operation Ross Zwisler
2017-02-17  3:52     ` Ross Zwisler
2017-02-17  3:52     ` Ross Zwisler
2017-02-17  3:56     ` Dan Williams
2017-02-17  3:56       ` Dan Williams
2017-02-17  3:56       ` Dan Williams
2017-01-20  3:50 ` [PATCH 04/13] dax, pmem: introduce an optional 'flush' " Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50 ` [PATCH 05/13] x86, dax: replace clear_pmem() with open coded memset + dax_ops->flush Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20 10:27   ` Jan Kara
2017-01-20 10:27     ` Jan Kara
2017-01-20 10:27     ` Jan Kara
2017-01-20 15:33     ` Dan Williams
2017-01-20 15:33       ` Dan Williams
2017-01-20 15:33       ` Dan Williams
2017-01-20  3:50 ` [PATCH 06/13] x86, dax, libnvdimm: move wb_cache_pmem() to libnvdimm Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50 ` [PATCH 07/13] x86, libnvdimm, pmem: move arch_invalidate_pmem() " Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50 ` [PATCH 08/13] x86, libnvdimm, dax: stop abusing __copy_user_nocache Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-01-20  3:50   ` Dan Williams
2017-03-28 16:21   ` Ross Zwisler
2017-03-28 16:21     ` Ross Zwisler
2017-03-28 16:21     ` Ross Zwisler
2017-03-28 16:26     ` Dan Williams
2017-03-28 16:26       ` Dan Williams
2017-03-28 16:26       ` Dan Williams
2017-01-20  3:51 ` [PATCH 09/13] libnvdimm, pmem: implement cache bypass for all copy_from_iter() operations Dan Williams
2017-01-20  3:51   ` Dan Williams
2017-01-20  3:51   ` Dan Williams
2017-01-20  3:51 ` [PATCH 10/13] libnvdimm, pmem: fix persistence warning Dan Williams
2017-01-20  3:51   ` Dan Williams
2017-01-20  3:51   ` Dan Williams
2017-01-20  3:51 ` [PATCH 11/13] libnvdimm, nfit: enable support for volatile ranges Dan Williams
2017-01-20  3:51   ` Dan Williams
2017-01-20  3:51   ` Dan Williams
2017-01-20  3:51 ` [PATCH 12/13] libnvdimm, pmem: disable dax flushing when pmem is fronting a volatile region Dan Williams
2017-01-20  3:51   ` Dan Williams
2017-01-20  3:51   ` Dan Williams
2017-01-20  3:51 ` [PATCH 13/13] libnvdimm, pmem: disable dax flushing for 'cache flush on fail' platforms Dan Williams
2017-01-20  3:51   ` Dan Williams
2017-01-20  3:51   ` Dan Williams
     [not found] ` <148488421301.37913.12835362165895864897.stgit-p8uTFz9XbKj2zm6wflaqv1nYeNYlB/vhral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2017-01-21 16:28   ` [PATCH 00/13] dax, pmem: move cpu cache maintenance to libnvdimm Matthew Wilcox
2017-01-21 16:28     ` Matthew Wilcox
2017-01-21 17:52     ` Christoph Hellwig
2017-01-21 17:52       ` Christoph Hellwig
2017-01-21 17:52       ` Christoph Hellwig
2017-01-21 17:52       ` Christoph Hellwig
     [not found]       ` <20170121175212.GA28180-jcswGhMUV9g@public.gmane.org>
2017-01-22 15:43         ` Matthew Wilcox
2017-01-22 15:43           ` Matthew Wilcox
2017-01-22 15:43           ` Matthew Wilcox
2017-01-22 16:29           ` Christoph Hellwig
2017-01-22 16:29             ` Christoph Hellwig
2017-01-22 16:29             ` Christoph Hellwig
2017-01-22 16:29             ` Christoph Hellwig
2017-01-22 18:19             ` Matthew Wilcox [this message]
2017-01-22 18:19               ` Matthew Wilcox
2017-01-22 18:30               ` Christoph Hellwig
2017-01-22 18:30                 ` Christoph Hellwig
2017-01-22 18:30                 ` Christoph Hellwig
2017-01-22 18:30                 ` Christoph Hellwig
     [not found]                 ` <20170122183046.GA7359-jcswGhMUV9g@public.gmane.org>
2017-01-22 18:39                   ` Matthew Wilcox
2017-01-22 18:39                     ` Matthew Wilcox
2017-01-22 18:39                     ` Matthew Wilcox
2017-01-22 18:44                     ` Christoph Hellwig
2017-01-22 18:44                       ` Christoph Hellwig
2017-01-22 18:44                       ` Christoph Hellwig
2017-01-22 18:44                       ` Christoph Hellwig
2017-01-23  6:37                       ` Matthew Wilcox
2017-01-23  6:37                         ` Matthew Wilcox
2017-01-23  7:10                         ` Dan Williams
2017-01-23  7:10                           ` Dan Williams
2017-01-23  7:10                           ` Dan Williams
2017-01-23  7:10                           ` Dan Williams
2017-01-23 16:00                           ` Christoph Hellwig
2017-01-23 16:00                             ` Christoph Hellwig
2017-01-23 16:00                             ` Christoph Hellwig
2017-01-23 17:14                             ` Dan Williams
2017-01-23 17:14                               ` Dan Williams
2017-01-23 17:14                               ` Dan Williams
2017-01-23 18:03                               ` Christoph Hellwig
2017-01-23 18:03                                 ` Christoph Hellwig
2017-01-23 18:03                                 ` Christoph Hellwig
2017-01-23 18:03                                 ` Christoph Hellwig
2017-01-23 18:31                                 ` Dan Williams
2017-01-23 18:31                                   ` Dan Williams
2017-01-23 18:31                                   ` Dan Williams
2017-01-23 18:31                                   ` Dan Williams
2017-01-23 15:58                         ` Christoph Hellwig
2017-01-23 15:58                           ` Christoph Hellwig
2017-01-23 15:58                           ` Christoph Hellwig
2017-01-22 17:30       ` Dan Williams
2017-01-22 17:30         ` Dan Williams
2017-01-22 17:30         ` Dan Williams
2017-01-22 17:30         ` Dan Williams
2017-01-23 16:01         ` Christoph Hellwig
2017-01-23 16:01           ` Christoph Hellwig
2017-01-23 16:01           ` Christoph Hellwig
2017-01-23 16:01           ` Christoph Hellwig

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