From: Sarah Sharp <sarah.a.sharp-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
To: David Laight <David.Laight-ZS65k/vG3HxXrIkS9f7CXA@public.gmane.org>
Cc: Alan Stern
<stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org>,
Ben Hutchings
<bhutchings-s/n/eUQHGBpZroRs9YW3xA@public.gmane.org>,
netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] usb: xhci: Link TRB must not occur with a USB payload burst.
Date: Wed, 20 Nov 2013 10:39:11 -0800 [thread overview]
Message-ID: <20131120183911.GE9611@xanatos> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6026B743D-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
On Wed, Nov 20, 2013 at 05:16:12PM -0000, David Laight wrote:
> > Ok, so the networking layer should be fine. However, with the current
> > patch, if the mass storage driver sends down a scatter-gather list
> > that's bigger than a ring segment, or needs to be split up so it doesn't
> > cross 64K boundaries, then the URB submission will fail. We don't want
> > that to happen.
>
> My suspicion is that long SG lists are unusual - otherwise the
> ring expansion code would have been needed much earlier.
>
> Can anyone remember whether that was needed because of long SG lists
> or because of large numbers of outstanding requests?
>
> I've seen it for network cards - but only because usbnet sends
> down far too many tx buffers.
It was added because USB video and audio drivers queue isochronous URBs
with lots of buffers for each service interval. So basically, lots of
outstanding requests, not long SG lists was the driving motivation to
add the ring expansion.
Sarah Sharp
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next prev parent reply other threads:[~2013-11-20 18:39 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-07 17:20 [PATCH] usb: xhci: Link TRB must not occur with a USB payload burst David Laight
2013-11-08 0:18 ` Sarah Sharp
2013-11-08 10:47 ` David Laight
2013-11-08 16:45 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1311081119510.1162-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2013-11-08 17:39 ` David Laight
2013-11-08 18:12 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1311081303460.1162-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2013-11-11 17:12 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6026B73FE-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2013-11-11 20:34 ` Alan Stern
2013-11-12 9:43 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6026B73FF-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2013-11-12 16:08 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1311121051090.1200-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2013-11-12 16:50 ` David Laight
2013-11-12 19:00 ` Alan Stern
2013-11-13 9:28 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6026B740B-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2013-11-13 16:20 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1311131113090.1424-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2013-11-13 16:58 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6026B741A-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2013-11-16 1:38 ` Ben Hutchings
[not found] ` <1384565904.29151.66.camel-/LGg1Z1CJKQ+9kgCwbf1HqK4ta4zdZpAajtMo4Cw6ucAvxtiuMwx3w@public.gmane.org>
2013-11-18 9:48 ` David Laight
2013-11-18 15:03 ` Ben Hutchings
[not found] ` <1384787003.10077.34.camel-nDn/Rdv9kqW9Jme8/bJn5UCKIB8iOfG2tUK59QYPAWc@public.gmane.org>
2013-11-18 15:41 ` David Laight
2013-11-19 22:58 ` Sarah Sharp
2013-11-20 3:09 ` Alan Stern
2013-11-20 9:36 ` David Laight
2013-11-20 15:03 ` Eric Dumazet
[not found] ` <1384959827.8604.141.camel-XN9IlZ5yJG9HTL0Zs8A6p/gx64E7kk8eUsxypvmhUTTZJqsBc5GL+g@public.gmane.org>
2013-11-20 15:54 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6026B7437-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2013-11-20 16:06 ` Sarah Sharp
2013-11-20 17:02 ` David Laight
2013-11-20 17:16 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6026B743D-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2013-11-20 18:39 ` Sarah Sharp [this message]
2013-11-20 21:11 ` Paul Zimmerman
2013-11-21 9:53 ` David Laight
2013-11-20 9:46 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6026B7438-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2013-11-20 16:26 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1311201121350.1826-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2013-11-20 17:08 ` David Laight
2013-11-20 16:50 ` Sarah Sharp
[not found] ` <Pine.LNX.4.44L0.1311111525480.17105-100000-pYrvlCTfrz9XsRXLowluHWD2FQJk+8+b@public.gmane.org>
2013-11-12 17:15 ` Sarah Sharp
2013-11-12 17:33 ` David Laight
2013-11-12 19:22 ` Alan Stern
2013-11-13 9:45 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6026B740C-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2013-11-13 16:27 ` Alan Stern
2013-11-08 11:07 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6026B73F1-CgBM+Bx2aUAnGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2013-11-12 17:15 ` Sarah Sharp
2013-11-12 17:28 ` David Laight
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