Date: Sat, 13 Jul 2024 20:58:07 -0700 From: Rick Macklem <rick.macklem@gmail.com> To: Garrett Wollman <wollman@bimajority.org> Cc: freebsd-stable@freebsd.org Subject: Re: Possible bug in zfs send or pipe implementation? Message-ID: <CAM5tNy5Lg8YZ=ad8YP69tzDFYroFy=UTL=K=J592JSG%2Bf5hyKA@mail.gmail.com> In-Reply-To: <CAM5tNy5m9-rqNTWJP5wAs9FewB6=FW9XbAe4V7qLgnrYJkSFKA@mail.gmail.com> References: <26259.12713.114036.564205@hergotha.csail.mit.edu> <CAM5tNy4pPF9mHdXM5W6gjztm4_TtFfXnOLu3cdkqvaRf3Ab5uA@mail.gmail.com> <26259.17366.276955.824313@hergotha.csail.mit.edu> <CAM5tNy5m9-rqNTWJP5wAs9FewB6=FW9XbAe4V7qLgnrYJkSFKA@mail.gmail.com>
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On Sat, Jul 13, 2024 at 8:50=E2=80=AFPM Rick Macklem <rick.macklem@gmail.co= m> wrote: > > On Sat, Jul 13, 2024 at 8:19=E2=80=AFPM Garrett Wollman <wollman@bimajori= ty.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 mi= ght > > > 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"? If I am reading the code correctly, if it sleeping on "pipewr", it is out of space and that is controlled via: kern.ipc.maxpipekva and you can see what it is using by looking at kern.ipc.pipekva (Unfortunately, I don't think you can change kern.ipc.maxpipekva on the fly= . It looks like it is a loader tunable, so you'd need to reboot to make it larger.) Anyhow, you can take a look at the sysctls. They might help? There is quite a detailed comment in sys/kern/sys_pipe.c related to this. rick > (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 tr= y 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 > >
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