i am sending data to a display device connected to a serial port. i manage to check for buffer overflow for the device itself by checking for flow control on the display device and thereby throttling writes to it (essentially using sleep). the problem i think i am facing is on the serial port side where the buffer on the serial port is getting overloaded. i am pasting relevant code here..

 

open DisplayIO, "+> /dev/cuaa1"        # open serial (display) device
        or die ("Can't open tty: $!") ;

sub main ()
{ 
        #code to loop &scrollTest several times with a sleep of 1 sec.
+..
}

sub process_keyboard_input ()
{
    syswrite DisplayIO, $KeyBoardInput ; # write to display
} # process_keyboard_input 

sub scrollTest {

        syswrite DisplayIO, sprintf ("%c%c", 0xfe, 0x51);
        $KeyBoardInput = sprintf ("%cE%cX%s", 0xfe,0xfe,'HHHHHHHHHHHHH
+HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH')
+;
    process_keyboard_input ();
        sleep(1);
}

..
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The pattern on 'H's fills the display as expected. The issue is that after about 50 loops or so, i get "tty-level buffer overflows" messages continously whenever the next syswrite takes place and eventually the display (or) serial port hangs. i think the issue is with the buffer handling with the serial port. anyone would know how i can set up buffer overflow control so that i dont jam up the serial port? thanks in advance..