From: Steven Stallion <sstallion@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] zero copy & 9p (was Re: PDP11 (Was: Re: what heavy negativity!)
Date: Wed, 10 Oct 2018 21:26:36 -0500 [thread overview]
Message-ID: <CAGGHmKFCEhm81MqiqjmJ6Z+f+Grc9K9zXTTR123sEffL8Enw8A@mail.gmail.com> (raw)
In-Reply-To: <CAEoi9W62qFgB2tj=aKEZ=PusHObnTwTDbGBqFBmzgmu=Sfepjg@mail.gmail.com>
On Wed, Oct 10, 2018 at 8:20 PM Dan Cross <crossd@gmail.com> wrote:
>> don't forget the code complexity with dealing with these scattered
>> pages in the *DRIVERS*.
>
> It's really not that hard. The way Linux does it is pretty bad, but it's not like that's the only way to do it.
SunOS and Win32 (believe it or not) managed to get this "right";
dealing with zero-copy in those kernels was a non-event. I'm not sure
I understand the assertion how this would affect constituent drivers.
This sort of detail is handled at a higher level - the driver
generally operates on a buffer that gets jammed into a ring for DMA
transfer. Apart from grabbing the physical address, the worst you may
have to do is pin/unpin the block for the DMA operation. From the
driver's perspective, it's memory. It doesn't matter where it came
from (or who owns it for that matter).
> Or don't.
There's a lot to be said for keeping it simple...
next prev parent reply other threads:[~2018-10-11 2:26 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-10 23:58 cinap_lenrek
2018-10-11 0:56 ` Dan Cross
2018-10-11 2:26 ` Steven Stallion [this message]
2018-10-11 2:30 ` Bakul Shah
2018-10-11 3:20 ` Steven Stallion
2018-10-11 14:21 ` [9fans] ..... UNSUBSCRIBE_HELP NEEDED DHAN HURLEY
-- strict thread matches above, loose matches on Subject: below --
2018-10-10 17:34 [9fans] PDP11 (Was: Re: what heavy negativity!) cinap_lenrek
2018-10-10 21:54 ` Steven Stallion
2018-10-10 22:26 ` [9fans] zero copy & 9p (was " Bakul Shah
2018-10-10 22:52 ` Steven Stallion
2018-10-11 20:43 ` Lyndon Nerenberg
2018-10-11 22:28 ` hiro
2018-10-12 6:04 ` Ori Bernstein
2018-10-13 18:01 ` Charles Forsyth
2018-10-13 21:11 ` hiro
2018-10-14 5:25 ` FJ Ballesteros
2018-10-14 7:34 ` hiro
2018-10-14 7:38 ` Francisco J Ballesteros
2018-10-14 8:00 ` hiro
2018-10-15 16:48 ` Charles Forsyth
2018-10-15 17:01 ` hiro
2018-10-15 17:29 ` hiro
2018-10-15 23:06 ` Charles Forsyth
2018-10-16 0:09 ` erik quanstrom
2018-10-17 18:14 ` Charles Forsyth
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=CAGGHmKFCEhm81MqiqjmJ6Z+f+Grc9K9zXTTR123sEffL8Enw8A@mail.gmail.com \
--to=sstallion@gmail.com \
--cc=9fans@9fans.net \
/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).