just set the MTU on the sender to something really small (120 byres)
On Mon, 10 Sep 2001, Jonathan Lemon wrote:
> In article <local.mail.freebsd-hackers/[EMAIL PROTECTED]> you write:
> >
> >[EMAIL PROTECTED] (Alfred Perlstein) writes:
> >> there's a setsockopt for this called TCP_NODELAY in netinet/tcp.h.
> >>
> >> you should read further into stevens before posting such questions.
> >
> >I seem to have expressed myself really bad :-( I want to debug an
> >application. We have had code that broke only occasionally on a
> >specific Linux version under heavy load. I want to detect bad code
> >like that and had hoped that some FreeBSD hackers had some tricks how
> >to use kernel configuration to do that.
> >
> >If application A do a write like
> >
> > write(socket, buf, 100);
> >
> >and application B read this like
> >
> > read(socket, buf, 100);
> >
> >without checking the result from the read operation, then this code
> >will probably work 99.9999% of the time. But if I could force the
> >kernel to pass data from a socket on to the application say one byte
> >at the time then this code will break 100% of the time. This makes
> >finding these problems more easy.
> >
> >This is highly simplified example, else I could just grep the sources
> >for all calls to read() and manually inspect the code. The data is
> >passed on to other parts of the system using message queues.
> >
> >But using the kernel to debug user applications like this was probably
> >a stupid idea. I'm sorry for posting a question to this group without
> >the proper knowledge wasting your time,
>
> One thing you might want to try doing is to write your own read()
> function and link against that. Your modified version could then
> replace the nbytes value with something smaller, for debugging purposes.
> --
> Jonathan
>
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