Newsgroups: comp.sys.transputer
From: andyr@wizzy.com (Andy Rabagliati)
Subject: Re: One dumb question about DMA
Organization: W.Z.I.
Date: Mon, 27 Jun 1994 19:19:24 GMT
Message-ID: <Cs2LoC.6G1@wizzy.com>

In article <ctcCs2EHz.LDF@netcom.com>, Chris <ctc@netcom.com> wrote:

> I tried to run some Link DMA transfers in low priority while servicing
>Eventreq interrupt in high priority. However, as soon as I service the
>interrupt, all DMA transfers stop until I finish and deschedule the
>interrupt routine. I thought once the DMA is set, the link engines
>will take care of the link transfer with no processor intervention, no
>matter whether you are in high or low priority. Is this the way that
>transputer supposed to response or am I missing something ?

By "run some Link DMA transfers" I presume you mean ordinary
input/output on the links.

It would help to know your environment, compilers, languages, use or not
of the Virtual Channel libraries, etc.

At the machine level, DMA link transfers will continue, subject to
access to memory bandwidth.

Access to the memory interface is on a round-robin basis, and is not
dependent on the priority of the communicating process.

So I guess we are missing some details of your setup.

Cheers,     Andy.

--
To see the world in a grain of sand,        Andy Rabagliati   andyr@wizzy.com
and heaven in a wild flower,                                W.Z.I. Consulting
Hold infinity in the palm of your hand,
and eternity in an hour.	-- William Blake

