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Re: netbsd-5 deadlocks when memory is low

On Fri, Sep 02, 2011 at 06:54:55AM +0200, Emmanuel Dreyfus wrote:
> A common case of deadlocks is ioflush waiting for the filesystem and the
> filesystem waiting for memory.

I made some progress in my understanding of the issue: the filesystem
server (perfused) gets swaped out and this is why all attemps to sync
PUFFS vnode deadlock. 

We need a way of avoiding that situation. A first idea would be that
PUFFS could detect the filesystem server and tag it so that it does not
get swapped, but that will not work with perfused, since it is just a
relay to a FUSE filesystem server (here glusterfsd). The FUSE filesystem
server needs to be unswappable as well.

So it seems we need a way for a process to tell the kernel that it
should not be swapped out. What about a sysctl proc.*.wired, accessible
only by root and defaulting to 0? 

Emmanuel Dreyfus

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