All of lore.kernel.org
 help / color / mirror / Atom feed
From: Geir Thomassen <geirt@powertech.no>
To: linux-kernel@vger.kernel.org
Subject: Re: Serial port latency
Date: Fri, 23 Mar 2001 15:43:44 +0100	[thread overview]
Message-ID: <3ABB6120.C8455DD8@powertech.no> (raw)
In-Reply-To: <3ABA42A8.A806D0E7@powertech.no> <20010323002516.B126@bug.ucw.cz>

Problem solved !

The main problem was that I didn't know that the equipment used
DTR as character acknowledge (not RTS/CTS which is common for flow
control). I didn't even bother to look at those lines with the
oscilloscope. Now the software runs fine with negligible latency.

Now the total latency is so low that the low_latency option to
setserial really matters, it reduces the total run time of my
program with 38 %

I don't get any measurable speed improvement by forcing the UART
to be detected as a 8250 or a 16450 though.

I have not tested with HZ=1000.

All in all, my problem is solved, thank you all.

Geir

  reply	other threads:[~2001-03-23 14:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-03-22 18:21 Serial port latency Geir Thomassen
2001-03-22 20:08 ` Theodore Tso
2001-03-22 20:32   ` Geir Thomassen
2001-03-22 20:55     ` Paul Fulghum
2001-03-22 22:44     ` Theodore Tso
     [not found] ` <20010322141937.C22479@universal-fasteners.com>
2001-03-22 21:02   ` Geir Thomassen
2001-03-22 21:52 ` Jonathan Lundell
2001-03-22 23:25 ` Pavel Machek
2001-03-23 14:43   ` Geir Thomassen [this message]
     [not found] <Pine.LNX.4.20.0103221219410.3343-100000@linuxtaj.korpivaara.org>
2001-03-22 20:03 ` Geir Thomassen
2001-03-22 20:17   ` Trent Jarvi
  -- strict thread matches above, loose matches on Subject: below --
2001-03-22 21:45 Manfred Spraul
     [not found] <000401c0b319517fea9@local>
2001-03-25 23:10 ` Pavel Machek
2001-03-29  7:58   ` Manfred Spraul
2001-03-30 22:36     ` Pavel Machek
2001-03-31 22:09       ` Manfred Spraul
2001-04-10  0:37   ` Andrea Arcangeli

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=3ABB6120.C8455DD8@powertech.no \
    --to=geirt@powertech.no \
    --cc=linux-kernel@vger.kernel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.