Date: Wed, 6 Mar 2013 22:55:36 -0800 From: John-Mark Gurney <jmg@funkthat.com> To: Karl Denninger <karl@denninger.net> Cc: freebsd-stable@freebsd.org Subject: Re: ZFS "stalls" -- and maybe we should be talking about defaults? Message-ID: <20130307065536.GA50035@funkthat.com> In-Reply-To: <5135EB62.6060006@denninger.net> References: <513524B2.6020600@denninger.net> <89680320E0FA4C0A99D522EA2037CE6E@multiplay.co.uk> <20130305050539.GA52821@anubis.morrow.me.uk> <20130305053249.GA38107@icarus.home.lan> <545CD2ABE3D146F2B91963ADF6090CDE@multiplay.co.uk> <20130305092700.GA43045@icarus.home.lan> <5135EB62.6060006@denninger.net>
next in thread | previous in thread | raw e-mail | index | archive | help
Karl Denninger wrote this message on Tue, Mar 05, 2013 at 06:56 -0600:
> When it happens on my system anything that is CPU-bound continues to
> execute. I can switch consoles and network I/O also works. If I have
> an iostat running at the time all I/O counters go to and remain at zero
> while the stall is occurring, but the process that is producing the
> iostat continues to run and emit characters whether it is a ssh session
> or on the physical console.
>
> The CPUs are running and processing, but all threads block if they
> attempt access to the disk I/O subsystem, irrespective of the portion of
> the disk I/O subsystem they attempt to access (e.g. UFS, swap or ZFS) I
> therefore cannot start any new process that requires image activation.
Since it seems like there is a thread that is spinning... Has anyone
thought to modify kgdb to mlockall it's memory and run it against the
current system (kgdb /boot/kernel/kernel /dev/mem), and then when the
thread goes busy, use kgdb to see what where it's spinning?
Just a thought...
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20130307065536.GA50035>