From: Dan Williams <dan.j.williams@intel.com> To: Linda Knippers <linda.knippers@hpe.com> Cc: Jan Kara <jack@suse.cz>, Matthew Wilcox <mawilcox@microsoft.com>, X86 ML <x86@kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>, Al Viro <viro@zeniv.linux.org.uk>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Christoph Hellwig <hch@lst.de> Subject: Re: [PATCH v4 12/16] libnvdimm, nfit: enable support for volatile ranges Date: Thu, 29 Jun 2017 13:42:19 -0700 [thread overview] Message-ID: <CAPcyv4jr0U-a521+wAL7RDca_AoUrtvO6yeY6d0UQpY7d=CHuQ@mail.gmail.com> (raw) In-Reply-To: <595552F5.5040008@hpe.com> On Thu, Jun 29, 2017 at 12:20 PM, Linda Knippers <linda.knippers@hpe.com> wrote: > On 06/29/2017 01:54 PM, Dan Williams wrote: >> Allow volatile nfit ranges to participate in all the same infrastructure >> provided for persistent memory regions. > > This seems to be a bit more than "other rework". It's part of the rationale for having a "write_cache" control attribute. There's only so much I can squeeze into the subject line, but it is mentioned in the cover letter. >> A resulting resulting namespace >> device will still be called "pmem", but the parent region type will be >> "nd_volatile". > > What does this look like to a user or admin? How does someone know that > /dev/pmemX is persistent memory and /dev/pmemY isn't? Someone shouldn't > have to weed through /sys or ndctl some other interface to figure that out > in the future if they don't have to do that today. We have different > names for BTT namespaces. Is there a different name for volatile ranges? No, the block device name is still /dev/pmem. It's already the case that you need to check behind just the name of the device to figure out if something is actually volatile or not (see memmap=ss!nn configurations), so I would not be in favor of changing the device name if we think the memory might not be persistent. Moreover, I think it was a mistake that we change the device name for btt or not, and I'm glad Matthew talked me out of making the same mistake with memory-mode vs raw-mode pmem namespaces. So, the block device name just reflects the driver of the block device, not the properties of the device, just like all other block device instances. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com> To: Linda Knippers <linda.knippers@hpe.com> Cc: "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>, Jan Kara <jack@suse.cz>, Matthew Wilcox <mawilcox@microsoft.com>, X86 ML <x86@kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Al Viro <viro@zeniv.linux.org.uk>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Christoph Hellwig <hch@lst.de> Subject: Re: [PATCH v4 12/16] libnvdimm, nfit: enable support for volatile ranges Date: Thu, 29 Jun 2017 13:42:19 -0700 [thread overview] Message-ID: <CAPcyv4jr0U-a521+wAL7RDca_AoUrtvO6yeY6d0UQpY7d=CHuQ@mail.gmail.com> (raw) In-Reply-To: <595552F5.5040008@hpe.com> On Thu, Jun 29, 2017 at 12:20 PM, Linda Knippers <linda.knippers@hpe.com> wrote: > On 06/29/2017 01:54 PM, Dan Williams wrote: >> Allow volatile nfit ranges to participate in all the same infrastructure >> provided for persistent memory regions. > > This seems to be a bit more than "other rework". It's part of the rationale for having a "write_cache" control attribute. There's only so much I can squeeze into the subject line, but it is mentioned in the cover letter. >> A resulting resulting namespace >> device will still be called "pmem", but the parent region type will be >> "nd_volatile". > > What does this look like to a user or admin? How does someone know that > /dev/pmemX is persistent memory and /dev/pmemY isn't? Someone shouldn't > have to weed through /sys or ndctl some other interface to figure that out > in the future if they don't have to do that today. We have different > names for BTT namespaces. Is there a different name for volatile ranges? No, the block device name is still /dev/pmem. It's already the case that you need to check behind just the name of the device to figure out if something is actually volatile or not (see memmap=ss!nn configurations), so I would not be in favor of changing the device name if we think the memory might not be persistent. Moreover, I think it was a mistake that we change the device name for btt or not, and I'm glad Matthew talked me out of making the same mistake with memory-mode vs raw-mode pmem namespaces. So, the block device name just reflects the driver of the block device, not the properties of the device, just like all other block device instances.
next prev parent reply other threads:[~2017-06-29 20:40 UTC|newest] Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-06-29 17:52 [PATCH v4 00/16] pmem: stop abusing copy_user_nocache(), and other reworks Dan Williams 2017-06-29 17:52 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 01/16] x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 02/16] dm: add ->copy_from_iter() dax operation support Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 03/16] filesystem-dax: convert to dax_copy_from_iter() Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 04/16] dax, pmem: introduce an optional 'flush' dax_operation Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 05/16] dm: add ->flush() dax operation support Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 06/16] filesystem-dax: convert to dax_flush() Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 07/16] x86, dax: replace clear_pmem() with open coded memset + dax_ops->flush Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 08/16] x86, dax, libnvdimm: remove wb_cache_pmem() indirection Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 09/16] x86, libnvdimm, pmem: move arch_invalidate_pmem() to libnvdimm Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 10/16] x86, libnvdimm, pmem: remove global pmem api Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:53 ` [PATCH v4 11/16] libnvdimm, pmem: fix persistence warning Dan Williams 2017-06-29 17:53 ` Dan Williams 2017-06-29 17:54 ` [PATCH v4 12/16] libnvdimm, nfit: enable support for volatile ranges Dan Williams 2017-06-29 17:54 ` Dan Williams 2017-06-29 19:20 ` Linda Knippers 2017-06-29 19:20 ` Linda Knippers 2017-06-29 20:42 ` Dan Williams [this message] 2017-06-29 20:42 ` Dan Williams 2017-06-29 21:16 ` Linda Knippers 2017-06-29 21:16 ` Linda Knippers 2017-06-29 21:50 ` Dan Williams 2017-06-29 21:50 ` Dan Williams 2017-06-29 22:12 ` Linda Knippers 2017-06-29 22:12 ` Linda Knippers 2017-06-29 22:28 ` Dan Williams 2017-06-29 22:28 ` Dan Williams 2017-06-29 22:35 ` Linda Knippers 2017-06-29 22:35 ` Linda Knippers 2017-06-29 22:43 ` Dan Williams 2017-06-29 22:43 ` Dan Williams 2017-06-29 22:49 ` Linda Knippers 2017-06-29 22:49 ` Linda Knippers 2017-06-29 22:58 ` Dan Williams 2017-06-29 22:58 ` Dan Williams 2017-06-29 23:14 ` Linda Knippers 2017-06-29 23:14 ` Linda Knippers 2017-06-30 1:28 ` Dan Williams 2017-06-30 1:28 ` Dan Williams 2017-07-05 23:46 ` Kani, Toshimitsu 2017-07-05 23:46 ` Kani, Toshimitsu 2017-07-06 0:07 ` Dan Williams 2017-07-06 0:07 ` Dan Williams 2017-07-06 1:17 ` Kani, Toshimitsu 2017-07-06 1:17 ` Kani, Toshimitsu 2017-07-06 2:08 ` Dan Williams 2017-07-06 2:08 ` Dan Williams 2017-07-06 2:11 ` hch 2017-07-06 2:11 ` hch 2017-07-06 2:53 ` Oliver 2017-07-06 2:53 ` Oliver 2017-07-06 2:56 ` hch 2017-07-06 2:56 ` hch 2017-06-29 17:54 ` [PATCH v4 13/16] dax: remove default copy_from_iter fallback Dan Williams 2017-06-29 17:54 ` Dan Williams 2017-06-29 17:54 ` [PATCH v4 14/16] dax: convert to bitmask for flags Dan Williams 2017-06-29 17:54 ` Dan Williams 2017-06-29 17:54 ` [PATCH v4 15/16] libnvdimm, pmem, dax: export a cache control attribute Dan Williams 2017-06-29 17:54 ` Dan Williams 2017-06-29 17:54 ` [PATCH v4 16/16] libnvdimm, pmem: disable dax flushing when pmem is fronting a volatile region Dan Williams 2017-06-29 17:54 ` Dan Williams
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