Messages in this thread | | | Date | Thu, 22 Mar 2001 14:08:52 -0600 | From | Theodore Tso <> | Subject | Re: Serial port latency |
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On Thu, Mar 22, 2001 at 07:21:28PM +0100, Geir Thomassen wrote: > My program controls a device (a programmer for microcontrollers) via the > serial port. The program sits in a tight loop, writing a few (typical 6) > bytes to the port, and waits for a few (typ. two) bytes to be returned from > the programmer.
Check out the man page for the "low_latency" configuration parameter in the setserial man page. This will cause the serial driver to burn a small amount of additional CPU overhead when processing characters, but it will lower the time between when characters arrive at the RS-232 port and when they are made available to the user program. The preferable solution is to use a intelligent windowing protocol that isn't heavily latency dependent (all modern protocols, such as kermit, zmodem, tcp/ip, etc. do this). But if you can't, using setserial to set the "low_latency" flag will allow you to work around a dumb communications protocol.
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