Re: Possible bug in zfs send or pipe implementation?

On Sat, Jul 13, 2024 at 8:19 PM Garrett Wollman <wollman@bimajority.org> wrote:
>
> <<On Sat, 13 Jul 2024 19:42:32 -0700, Rick Macklem <rick.macklem@gmail.com> said:
>
> > # ps axHl
> > should show you what wchan's the processes are waiting on and that might
> > give you a clue w.r.t. what is happening?
>
> zfs is waiting to write into the pipe and pv (the progress meter) is
> waiting in select.
Just to clarify it, are you saying zfs is sleeping on "pipewr"?
(There is also a msleep() for "pipbww" in pipe_write().)

rick

>
> > If is easy to build a kernel from sources and boot that, you could try defining
> > PIPE_NODIRECT in sys/kern/sys_pipe.c and see if that avoids the hangs?
>
> It's easy to build a kernel from sources, but not easy to reboot the
> server -- it's being retired shortly, and because of time constraints
> I need to get it drained before the next scheduled outage.
>
> -GAWollman
>