DragonFly users List (threaded) for 2006-01
Re: copying pkgsrc tree around jails on beefy machine - fast on 2nd iteration, a bit slower than first on 3rd iteration
:If the machine has 3-4GB of memory why shouldn't the vnode and buffer
:cache do some better auto tunning. If the kernel has a VM system
:shouldn't the kernel be aware of how much memory is in use for the
:entire system and make all of the system caches larger ?
The kernel is fairly conservative with regards to the number of vnodes
it allows to be cached because the memory required to hold the vnodes
and related VM structures can exceed the kernel's own fairly limited
address space. When doing copy operations on large numbers of small
files, the vnode limit will often be hit before the memory limit.
(When copying larger files the memory limit is hit before the vnode
You can adjust the number of vnodes the kernel caches with the
'kern.maxvnodes' sysctl. So, e.g. /usr/pkgsrc has around 105000
files so if you want to support caching of a cpdup you would need
to be able to cache ~210000 vnodes. If you make the number too
big, however, you run a serious risk of running the kernel out of
Unless you actually *NEED* to cache whole file structures for
performance reasons in a production environment, I would *NOT*
recommend that the system default be changed.