Subject: Re: momentary freezes in -current
To: Jukka Marin <email@example.com>
From: Daniel Carosone <firstname.lastname@example.org>
Date: 07/26/2006 07:33:27
Content-Type: text/plain; charset=us-ascii
On Mon, Jul 24, 2006 at 01:16:30PM +0300, Jukka Marin wrote:
> A few times during the copy, the system froze completely and then
> woke up again.=20
This is the same issue Thor described just a few days ago in response
to another question on, I think, tech-kern.
Softdep is generating a huge flood of metadata writes, many more than
the disk subsystem can process, and ~everything gets jammed waiting
for those to clear. Processes blocking directly on the disk get
starved, and other processes can get stuck on the vnode lock for the
root of the filesystem.
It's not hung, though it can seem that way especially if you're
running X and the Xserver is one of the processes that gets stuck.
The condition is much more painfully apparent if you run with disk
write-cache off; it can easily persist for 20-30s at a time there.
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