> SMP should be the same from 2.0.18 upwards. The performance issues
> under heavy I/O load (losing serial chars, slipping clock) ...
Losing serial characters may not be an SMP problem. The current serial
driver ungracefully drops characters on the floor once its buffer fills
ch = serial_inp(info, UART_RX);
if (tty->flip.count >= TTY_FLIPBUF_SIZE)
*tty->flip.char_buf_ptr = ch;
So if it's not an interrupt latency problem, the characters may be
read from the port but then discarded. Perhaps it would be useful to
a printk() message for the first time a character is discarded this way.
(Better still, the flip buffer should be flipped when it fills, rather
than just when it's being emptied.)