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Date:   Wed, 6 Nov 2019 14:30:46 -0800
From:   Guenter Roeck <linux@roeck-us.net>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>, linux-kernel@vger.kernel.org,
        linux-nvme@lists.infradead.org,
        Akinobu Mita <akinobu.mita@gmail.com>,
        linux-pm@vger.kernel.org, Chris Healy <cphealy@gmail.com>
Subject: Re: [PATCH v2] nvme: Add hardware monitoring support
Message-ID: <20191106223046.GA19493@roeck-us.net>
References: <20191029223214.18889-1-linux@roeck-us.net>
 <20191030005327.GC15332@redsun51.ssa.fujisawa.hgst.com>
 <20191106212921.GA7020@amd>
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On Wed, Nov 06, 2019 at 10:29:21PM +0100, Pavel Machek wrote:
> Hi!
> 
> > > nvme devices report temperature information in the controller information
> > > (for limits) and in the smart log. Currently, the only means to retrieve
> > > this information is the nvme command line interface, which requires
> > > super-user privileges.
> > > 
> > > At the same time, it would be desirable to use NVME temperature information
> > > for thermal control.
> > > 
> > > This patch adds support to read NVME temperatures from the kernel using the
> > > hwmon API and adds temperature zones for NVME drives. The thermal subsystem
> > > can use this information to set thermal policies, and userspace can access
> > > it using libsensors and/or the "sensors" command.
> > > 
> > > Example output from the "sensors" command:
> > > 
> > > nvme0-pci-0100
> > > Adapter: PCI adapter
> > > Composite:    +39.0?C  (high = +85.0?C, crit = +85.0?C)
> > > Sensor 1:     +39.0?C
> > > Sensor 2:     +41.0?C
> > > 
> > > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> > 
> > This looks fine to me, but I'll wait a few more days to see if there are
> > any additional comments..
> 
> User wants to know temperature of /dev/sda... and we already have an
> userspace tools knowing about smart, etc...
> 
> pavel@amd:/data/film$ sudo hddtemp /dev/sda
> /dev/sda: ST1000LM014-1EJ164: 48?C
> 
> I see we also have sensors framework but it does _not_ handle
> harddrive temperatures.
> 
> Does it need some kind of unification? Should NVMe devices expose
> "SMART" information in the same way other SSDs do?
> 

The unification to report hardware monitoring information to userspace
is called the sensors framework. Also, users in general prefer to not
have to run "sudo" to get such information.

Guenter