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From: Christoph Hellwig <hch@infradead.org>
To: Juergen Gross <jgross@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	linux-scsi@vger.kernel.org, nab@linux-iscsi.org,
	JBottomley@parallels.com, xen-devel@lists.xen.org,
	hch@infradead.org, target-devel@vger.kernel.org,
	david.vrabel@citrix.com, JBeulich@suse.com
Subject: Re: [Xen-devel] [PATCH V5 2/5] Add XEN pvSCSI protocol description
Date: Fri, 22 Aug 2014 05:04:30 -0700	[thread overview]
Message-ID: <20140822120430.GA28916@infradead.org> (raw)
In-Reply-To: <53F6C47B.5010900@suse.com>

On Fri, Aug 22, 2014 at 06:18:03AM +0200, Juergen Gross wrote:
> >>The resulting number of struct scsiif_request_segment is the sum of
> >>seg[0..nr_segments-1].length / sizeof(struct scsiif_request_segment).
> >>
> >
> >Where the nr_segments can only go Up to VSCSIIF_SG_TABLESIZE, so the max
> >total SG entries you can is 13312 ( 4096 / 8 = 512 max per page, times
> >26).
> 
> In theory, yes. SG_ALL (being 128 today) is limiting this value.

Note that SG_ALL (or SCSI_MAX_SG_SEGMENTS which is a better name for it)
is only the maximum if your driver doesn't support S/G chaining.  Given
that it and the Xen infrastructure seems to use the proper s/g list
helpers it should support SCSI_MAX_SG_CHAIN_SEGMENTS easily.

  reply	other threads:[~2014-08-22 12:04 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-18  9:31 [PATCH V5 0/5] Add XEN pvSCSI support jgross
2014-08-18  9:31 ` [PATCH V5 1/5] xen/events: support threaded irqs for interdomain event channels jgross
2014-08-20 13:09   ` [Xen-devel] " Konrad Rzeszutek Wilk
2014-08-20 13:09   ` Konrad Rzeszutek Wilk
2014-08-18  9:31 ` jgross
2014-08-18  9:31 ` [PATCH V5 2/5] Add XEN pvSCSI protocol description jgross
2014-08-20 13:25   ` Konrad Rzeszutek Wilk
2014-08-20 13:25   ` [Xen-devel] " Konrad Rzeszutek Wilk
2014-08-20 14:01     ` Juergen Gross
2014-08-20 14:01     ` [Xen-devel] " Juergen Gross
2014-08-21 19:26       ` Konrad Rzeszutek Wilk
2014-08-21 19:26       ` [Xen-devel] " Konrad Rzeszutek Wilk
2014-08-22  4:18         ` Juergen Gross
2014-08-22 12:04           ` Christoph Hellwig [this message]
2014-08-22 12:04           ` Christoph Hellwig
2014-08-22  4:18         ` Juergen Gross
2014-08-22 10:52   ` David Vrabel
2014-08-22 10:52   ` David Vrabel
2014-08-18  9:31 ` jgross
2014-08-18  9:31 ` [PATCH V5 3/5] Introduce xen-scsifront module jgross
2014-08-18  9:31 ` jgross
2014-08-22 22:25   ` [Xen-devel] " Konrad Rzeszutek Wilk
2014-08-25 10:10     ` Juergen Gross
2014-08-25 10:10     ` Juergen Gross
2014-08-22 22:25   ` Konrad Rzeszutek Wilk
2014-08-18  9:31 ` [PATCH V5 4/5] Introduce XEN scsiback module jgross
2014-08-18  9:31 ` jgross
2014-08-18  9:31 ` [PATCH V5 5/5] add xen pvscsi maintainer jgross
2014-08-20 13:08   ` [Xen-devel] " Konrad Rzeszutek Wilk
2014-08-20 13:08   ` Konrad Rzeszutek Wilk
2014-08-26 14:14   ` David Vrabel
2014-08-26 14:23     ` [Xen-devel] " Juergen Gross
2014-08-26 16:37       ` James Bottomley
2014-08-26 16:37       ` [Xen-devel] " James Bottomley
2014-08-26 17:12         ` David Vrabel
2014-08-27  3:50           ` Juergen Gross
2014-08-27  3:50           ` Juergen Gross
2014-08-26 17:12         ` David Vrabel
2014-08-26 14:23     ` Juergen Gross
2014-08-26 14:14   ` David Vrabel
2014-08-18  9:31 ` jgross
2014-08-22 21:21 ` [PATCH V5 0/5] Add XEN pvSCSI support Nicholas A. Bellinger
2014-08-23  0:40   ` [Xen-devel] " Konrad Rzeszutek Wilk
2014-08-26 10:13     ` David Vrabel
2014-08-26 10:13     ` [Xen-devel] " David Vrabel
2014-08-26 13:55       ` Christoph Hellwig
2014-08-26 13:55       ` Christoph Hellwig
2014-08-23  0:40   ` Konrad Rzeszutek Wilk
2014-08-22 21:21 ` Nicholas A. Bellinger

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