From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
To: 鑫愿 <qiuxincsu-k+cT0dCbe1g@public.gmane.org>
Cc: Bart Van Assche
<bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>,
Jens Axboe <axboe-b10kYP2dOMg@public.gmane.org>,
"linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
James Bottomley
<jejb-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>,
"Martin K. Petersen"
<martin.petersen-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>,
Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Ming Lei <tom.leiming-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
"linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
Keith Busch <keith.busch-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Laurence Oberman
<loberman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>,
"tiger.zhao" <tiger.zhao-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>,
qiuxin <qiuxin-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
Subject: Re: A question regarding "multiple SGL"
Date: Thu, 27 Oct 2016 08:41:15 +0200 [thread overview]
Message-ID: <20161027064115.GA5864@lst.de> (raw)
In-Reply-To: <20161027005230.9904DC00097-2RFepEojUI2gQzYKMK1YzK/p1tWXv8elb9TvmfFkwKk@public.gmane.org>
Hi Robert,
There is no feature called "Multiple SGL in one NVMe capsule". The
NVMe over Fabrics specification allows a controller to advertise how
many SGL descriptors it supports using the MSDBD Identify field:
"Maximum SGL Data Block Descriptors (MSDBD): This field indicates the
maximum number of (Keyed) SGL Data Block descriptors that a host is allowed to
place in a capsule. A value of 0h indicates no limit."
Setting this value to 1 is perfectly valid. Similarly a host is free
to chose any number of SGL descriptors between 0 (only for command that
don't transfer data) to the limit imposed by the controller using the
MSDBD field.
There are no plans to support a MSDBD value larger than 1 in the Linux
NVMe target, and there are no plans to ever submit commands with multiple
SGLs from the host driver either.
Cheers,
Christoph
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next parent reply other threads:[~2016-10-27 6:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20161027005230.9904DC00097@webmail.sinamail.sina.com.cn>
[not found] ` <20161027005230.9904DC00097-2RFepEojUI2gQzYKMK1YzK/p1tWXv8elb9TvmfFkwKk@public.gmane.org>
2016-10-27 6:41 ` Christoph Hellwig [this message]
2016-10-27 6:57 ` A question regarding "multiple SGL" Qiuxin (robert)
2016-10-27 7:10 ` Christoph Hellwig
[not found] ` <20161027071009.GA6434-jcswGhMUV9g@public.gmane.org>
2016-10-27 9:02 ` Sagi Grimberg
[not found] ` <178765fb-0fcf-0fdc-dc5e-0cc226375827-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
2016-10-27 14:50 ` Steve Wise
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