Garbage collection?

David W. Hankins dhankins at
Wed Sep 9 17:00:41 UTC 2009

On Wed, Sep 09, 2009 at 09:30:47AM -0500, Peter Laws wrote:
> Exactly what we did - 3600 to 1800.  May yet drop it to 900.

be careful driving the lease time too low.  the lower the lease time,
the greater the dhcp activity due to renewals.

dhcpd is still one-fsync-per-dhcprequest unless you explicitly enable
the somewhat experimental delayed-fsync feature in 4.1, so with enough
clients and a low enough lease time, you can quickly resource starve
your dhcpd.  pay attention to 'clients * 2 / avg-lease-time', this
should never approach your theoretical upper limit on fsync()/s (along
with other activity on the drive).

if you can identify the problematic clients (iphones) in a class
statement, you can lower the lease time for those clients
specifically, keeping your avg-lease-time higher.

David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins
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