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
next prev parent 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
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