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From:   Jeff Moyer <jmoyer@redhat.com>
To:     Keith Busch <keith.busch@intel.com>
Cc:     Dave Hansen <dave.hansen@linux.intel.com>, thomas.lendacky@amd.com,
        fengguang.wu@intel.com, dave@sr71.net, linux-nvdimm@lists.01.org,
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        baiyaowei@cmss.chinamobile.com, ying.huang@intel.com,
        bhelgaas@google.com, akpm@linux-foundation.org, bp@suse.de
Subject: Re: [PATCH 0/4] Allow persistent memory to be used like normal RAM
References: <20190116181859.D1504459@viggo.jf.intel.com>
        <x49sgxr9rjd.fsf@segfault.boston.devel.redhat.com>
        <20190117164736.GC31543@localhost.localdomain>
        <x49pnsv8am1.fsf@segfault.boston.devel.redhat.com>
        <20190117193403.GD31543@localhost.localdomain>
Date:   Thu, 17 Jan 2019 16:57:17 -0500
In-Reply-To: <20190117193403.GD31543@localhost.localdomain> (Keith Busch's
        message of "Thu, 17 Jan 2019 12:34:03 -0700")
Message-ID: <x49ef9b6j7m.fsf@segfault.boston.devel.redhat.com>
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Keith Busch <keith.busch@intel.com> writes:

>> Keith, you seem to be implying that there are platforms that won't
>> support memory mode.  Do you also have some insight into how customers
>> want to use this, beyond my speculation?  It's really frustrating to see
>> patch sets like this go by without any real use cases provided.
>
> Right, most NFIT reporting platforms today don't have memory mode, and
> the kernel currently only supports the persistent DAX mode with these.
> This series adds another option for those platforms.

All NFIT reporting platforms today are shipping NVDIMM-Ns, where it
makes absolutely no sense to use them as regular DRAM.  I don't think
that's a good argument to make.

> I think numactl as you mentioned is the first consideration for how
> customers may make use. Dave or Dan might have other use cases in mind.

Well, it sure looks like this took a lot of work, so I thought there
were known use cases or users asking for this functionality.

Cheers,
Jeff