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Re: Serial Latency Issues, Baud Rate Affects Buffering
----- Original Message -----
From: "Eric Sorton" <email@example.com>
To: "Mikael Starvik" <firstname.lastname@example.org>; "Johan Adolfsson"
Sent: den 12 januari 2004 14:36
Subject: Re: Serial Latency Issues, Baud Rate Affects Buffering
> All of these options expect the serial port to stop transmitting data for
> period of time before flushing the DMA buffer. Our stream transmits data
> almost continuously, thus the DMA buffer is never flushed UNTIL it is full
> 256 bytes, which at 4800 baud, is over 1/2 a second. Note, I still need
> try the code modification mentioned in a previous message.
> The new serial driver provides an option for disabling DMA. What are the
> repercussions of disabling DMA?
At low baudrates, it shouldn't really matter. At 115200 you might loose
a character now for and then though and above 115200 it's rather useless.
> Will this help reduce the latency in the
Yes, it should behave more like normal PC, the incoming data is put in
the flip buffer and pushed to the tty layer at each character interrupt.
> Thank you for all of your help, it is greatly appreciated,