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From: Klaus Jensen <its@irrelevant.dk>
To: Keith Busch <kbusch@kernel.org>
Cc: "Kevin Wolf" <kwolf@redhat.com>,
	"Niklas Cassel" <Niklas.Cassel@wdc.com>,
	qemu-block@nongnu.org, "Klaus Jensen" <k.jensen@samsung.com>,
	qemu-devel@nongnu.org,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: Re: [PATCH 3/9] hw/block/nvme: support per-namespace smart log
Date: Thu, 1 Oct 2020 19:18:37 +0200	[thread overview]
Message-ID: <20201001171837.GA792691@apples.localdomain> (raw)
In-Reply-To: <20201001152055.GA3343@C02WT3WMHTD6>

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On Oct  1 09:20, Keith Busch wrote:
> On Thu, Oct 01, 2020 at 06:10:57AM +0200, Klaus Jensen wrote:
> > On Sep 30 15:04, Keith Busch wrote:
> > > Let the user specify a specific namespace if they want to get access
> > > stats for a specific namespace.
> > > 
> > 
> > I don't think this makes sense for v1.3+.
> > 
> > NVM Express v1.3d, Section 5.14.1.2: "There is no namespace specific
> > information defined in the SMART / Health log page in this revision of
> > the specification.  therefore the controller log page and namespace
> > specific log page contain identical information".
> > 
> > I have no idea why the TWG decided this, but that's the way it is ;)
> 
> I don't think they did that. The behavior you're referring to is specific to
> controllers that operate a particular way: "If the log page is not supported on
> a per namespace basis ...". They were trying to provide a spec compliant way
> for controllers to return a success status if you supplied a valid NSID when
> the controller doesn't support per-namespace smart data..
> 
> The previous paragraph is more clear on this: "The controller may also support
> requesting the log page on a per namespace basis, as indicated by bit 0 of the
> LPA field in the Identify Controller data structure".

OK, so I agree that it makes sense for it to be supported on a per
namespace basis, but I think the spec is just keeping the door open for
future namespace specific stuff in the log page - currently there is
none.

Figure 94 (the actual SMART log page) says that the Data Units
Read/Written are controller wide, so there really is no namespace
specific information. Maybe this could be in the context of shared
namespaces? How would a controller know how much data has been
read/written from it without asking the other controllers? What if a
controller is detached from the namespace - you'd lose those numbers.

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  reply	other threads:[~2020-10-01 17:24 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-30 22:04 [PATCH 0/9] nvme qemu cleanups and fixes Keith Busch
2020-09-30 22:04 ` [PATCH 1/9] hw/block/nvme: remove pointless rw indirection Keith Busch
2020-10-01  4:05   ` Klaus Jensen
2020-10-01  8:48     ` Klaus Jensen
2020-10-01 15:24       ` Keith Busch
2020-10-01 18:34     ` Klaus Jensen
2020-10-06  1:49   ` Dmitry Fomichev
2020-09-30 22:04 ` [PATCH 2/9] hw/block/nvme: fix log page offset check Keith Busch
2020-09-30 23:18   ` Dmitry Fomichev
2020-10-01  4:05   ` Klaus Jensen
2020-10-01 10:11   ` Philippe Mathieu-Daudé
2020-09-30 22:04 ` [PATCH 3/9] hw/block/nvme: support per-namespace smart log Keith Busch
2020-10-01  4:10   ` Klaus Jensen
2020-10-01 15:20     ` Keith Busch
2020-10-01 17:18       ` Klaus Jensen [this message]
2020-10-01 17:30         ` Keith Busch
2020-10-01 17:34           ` Klaus Jensen
2020-10-02  8:48   ` Klaus Jensen
2020-10-06  1:57   ` Dmitry Fomichev
2020-09-30 22:04 ` [PATCH 4/9] hw/block/nvme: validate command set selected Keith Busch
2020-10-01  4:14   ` Klaus Jensen
2020-09-30 22:04 ` [PATCH 5/9] hw/block/nvme: support for admin-only command set Keith Busch
2020-10-01  0:11   ` Dmitry Fomichev
2020-10-01  4:17   ` Klaus Jensen
2020-09-30 22:04 ` [PATCH 6/9] hw/block/nvme: reject io commands if only admin command set selected Keith Busch
2020-09-30 23:11   ` Dmitry Fomichev
2020-09-30 22:04 ` [PATCH 7/9] hw/block/nvme: add nsid to get/setfeat trace events Keith Busch
2020-09-30 22:04 ` [PATCH 8/9] hw/block/nvme: add trace event for requests with non-zero status code Keith Busch
2020-09-30 23:21   ` Dmitry Fomichev
2020-10-01 15:25   ` Philippe Mathieu-Daudé
2020-09-30 22:04 ` [PATCH 9/9] hw/block/nvme: report actual LBA data shift in LBAF Keith Busch
2020-10-01  9:48   ` Klaus Jensen
2020-10-01 18:46 ` [PATCH 0/9] nvme qemu cleanups and fixes Klaus Jensen
2020-10-13  9:04 ` Klaus Jensen
2020-10-13 17:48   ` Keith Busch
2020-10-13 18:36     ` Klaus Jensen

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