Re: A peek at the future of storage

[Bernd Petrovitsch <bernd@firmix.at>]

On Mit, 2007-12-12 at 10:02 -0800, Daniel Phillips wrote:
> On Wednesday 12 December 2007 09:46, J. Bruce Fields wrote:
[...]
> > People have proposed writing a daemon that just reads
> > /proc/net/rpc/nfsd periodically and uses that to adjust the number of
> > threads from userspace, probably subject to some limits in a config
> > file someplace. (Think that could do the job, or is there some reason
[...]
> So how would a userspace daemon know that kernel is blocking and new 
> threads are needed?  In kernel this is pretty easy: when a new request 
> arrives, look on the thread list and if none are available, generate a 
> new one.  Something special needs to be done to handle the case where 
> there are no threads available because they are all piled up on a 
> semaphore due to, for example, somebody unplugging the network cable 
> for a remote disk.  We have to avoid generating infinite threads in 
> that case.  Ideas?

Add a sysctl configurable maximum number of NFS threads and default it
to 8 (or whatever now the default value is).
And one wants probably some logic to kill them again if they are not
used long enough. And then you need/want another variable for the
minimum number of NFS threads around.

	Bernd
-- 
Firmix Software GmbH                   http://www.firmix.at/
mobil: +43 664 4416156                 fax: +43 1 7890849-55
          Embedded Linux Development and Services


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/