From: hch@lst.de (Christoph Hellwig)
Subject: [PATCH] nvme-pci: Add Write Zero support to Intel 660p
Date: Fri, 2 Nov 2018 07:08:15 +0100 [thread overview]
Message-ID: <20181102060815.GA16583@lst.de> (raw)
In-Reply-To: <20181101143807.GL19483@localhost.localdomain>
On Thu, Nov 01, 2018@08:38:08AM -0600, Keith Busch wrote:
> We currently use DSM Deallocate for REQ_OP_WRITE_ZEROES. We don't care
> if the blocks are actually deallocated. We only care if reading them
> back determinisitically returns 0's, and DLFEAT tells us if we can rely
> on that behavior.
No, DLFEAT _only_ tells you the value you read from actually deallocated
blocks. From the DLFEAT description:
"Bits 2:0 indicate the values read from a deallocated logical block and its
metadata (excluding protection information). The values for this field have
the following meanings:"
And from Section 6.7:
"This command is advisory; a compliant controller may choose to take no
action based on information provided."
"Attribute ? Deallocate (AD): If set to ?1?, then the NVM subsystem may
deallocate all provided ranges. The data returned for a deallocated range
is specified in section 6.7.1.1."
next prev parent reply other threads:[~2018-11-02 6:08 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-26 22:41 [PATCH] nvme-pci: Add Write Zero support to Intel 660p Gwendal Grignou
2018-10-26 22:58 ` Keith Busch
2018-10-27 7:44 ` Christoph Hellwig
2018-10-27 9:19 ` Chaitanya Kulkarni
2018-10-29 15:24 ` Keith Busch
2018-11-01 5:27 ` Christoph Hellwig
2018-11-01 14:38 ` Keith Busch
2018-11-02 6:08 ` Christoph Hellwig [this message]
2018-11-02 14:21 ` Keith Busch
2018-11-03 8:21 ` Christoph Hellwig
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