🚀 go-pugleaf

In article <6eeve9$6l@stonix.demon.co.uk>,
Richard Lamont <richard@stonix.demon.co.uk> wrote:
>
>Surely ifconfig reports serial overruns?

It claims to, but it doesn't. I think this is because it's operating at
the wrong level. After all, it's designed to report overruns from Ethernet
cards and so forth, where the card can deliver data into Linux's internal
buffers far faster than the software can deal with it; here, the problem
is getting the data into Linux's buffers in the first place.

I think it's reporting overflows of those internal buffers (is it the TTY
flip buffer, or the TCP fragment reassembly queue? I've never quite worked
it out), not of the tiny FIFO inside the UART.

The easiest way to spot serial overflows is to not use irqtune and try
doing something that slams the disk at the same time as ftping something.
If the ftp transfer stops off dead when the disk access starts, you've got
overruns.[1]

[1] A tool like Andrew Bishop's ProcMeter (from
    http://www.gedanken.demon.co.uk/) is damn useful for reporting packet
    receive rates and interrupt levels - both of which tend to shadow
    each other fairly closely when heavy serial comm is going on.

-- 
`Oooo!  Saint Malcolm preserve us!  This is heresy.'