From: Roger Williams <roger@coelacanth.com>
To: linuxppc-dev@lists.linuxppc.org
Subject: MPC860 IDMA latency question
Date: 12 Aug 1999 03:04:11 -0400 [thread overview]
Message-ID: <m33dxpwkd0.fsf@grouper.coelacanth.com> (raw)
In-Reply-To: Benjamin Herrenschmidt's message of "Thu, 5 Aug 1999 13:56:11 +0200"
[I apologise for asking this here, but Motorola doesn't seem to host a
PPC mailing list like their other MCU lists.]
I'm having trouble getting the throughput estimated by Motorola for
peripheral -> memory IDMA transfers on the MPC860. In particular,
they seem to claim 10 MBytes/s for single-address (`fly-by') transfers
(level-sensitive DREQ on a 50 MHz part), but as I only get a new SDACK
every 30 clock cycles, I'm lucky to get 1.25 MWords/s, even with
memory set up for zero wait states.
Any ideas of what am I missing here? (Unfortunately, I can't try the
special single-buffer mode until I receive some rev C devices...)
--
Roger Williams finger me for my PGP public key
Coelacanth Engineering Inc consulting & turnkey product development
Middleborough, Massachusetts wireless * datacomm * DSP * ATE
tel +1 508 947-5585 * fax +1 508 861-0278 * http://www.coelacanth.com/
[[ This message was sent via the linuxppc-dev mailing list. Replies are ]]
[[ not forced back to the list, so be sure to Cc linuxppc-dev if your ]]
[[ reply is of general interest. Please check http://lists.linuxppc.org/ ]]
[[ and http://www.linuxppc.org/ for useful information before posting. ]]
reply other threads:[~1999-08-12 7:04 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=m33dxpwkd0.fsf@grouper.coelacanth.com \
--to=roger@coelacanth.com \
--cc=linuxppc-dev@lists.linuxppc.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).