Date: Tue, 23 Oct 2012 20:41:11 +0200
From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: Peter Hurley <peter@hurleysoftware.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        devel@driverdev.osuosl.org, linux1394-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [PATCH 0/1] staging: Add firewire-serial driver
Message-ID: <20121023204111.63e13986@stein>
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On Oct 23 Peter Hurley wrote:
> most controllers allow spillover into
> the portion of bus cycle assigned for sync tx (which is another 4Kbytes
> per 125us).

All controllers do so and are expected to do so.  Asynchronous traffic is
not supposed to depend on a cycle master being active.

> (Technical note: the actual total max for combined async
> and sync tx is 6144 bytes per 125us clock)

It depends on bus topology, transaction types, and more.  For a single-hop
S400 1394a bus (vulgo FireWire 400) I once calculated 44 MB/s bandwidth of
asynchronous unified write transactions:
http://marc.info/?l=linux1394-devel&m=109128028930225
That's at the physical layer; link layer and application layer performances
are less than that of course.
-- 
Stefan Richter
-=====-===-- =-=- =-===
http://arcgraph.de/sr/
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