Some ideas for FreeBSD

Jerry McAllister jerrymc at
Wed Feb 6 18:14:00 UTC 2008

On Wed, Feb 06, 2008 at 09:23:28AM -0800, millueradfa at wrote:

> Dear FreeBSD Developers,
> I have a few suggestions for how FreeBSD can be
> improved in an upcoming release. 

Sounds like you have your work cut out for you.


> My first is to allow for dynamically resizeable swap
> file of some sort, and via kqueue, a notification
> facility to notify a program when swap is about to run
> out, when a program has made a memory request which
> requires more swap space than is avialable, and when
> swap space is run out. There should also be commands
> that can shrink the swap files, and see how much is
> being used in the swap files. This allows for the user
> to write customised programs that can manage and
> allocate new swap space as needed. The OS can come
> with a standard version of such a program that allows
> a user to specify a maximum swap file size (including
> infinite).
> I have also run into problems with making multiple
> space files on the same disk, in trying to address
> these swap exhaust problems, which caused thrashing. I
> believe this happened to when the swap partition and a
> swap file were on the same drive. Perhaps a way should
> be looked at to have multiple swap partititions and
> files on the same disk. That could also allow another
> way for additional swap space to be allocated, but I
> dont know if having the possibility of a large number
> of swap files is less efficient than a dynamically
> growing swap file. There should also be a feature to
> see how much of the swap file is used.
> I would much rather have dynamically allocated and
> deallocated swap space so I do not have large unused
> swap space eating up the disk, than having to
> predefine the swap size. 
> Another idea I have is for setting the Do Not Fragment
> flag on a  per connection option for UDP connections,
> and a per connection option to disable UDP checksum. 
> The third idea is for more of a move to Linux and, SUS
> , and POSIX source compatability in regards to
> additional features supported by these systems. I
> still in 6.0 run into some calls that are not
> supported by FreeBSD that is a real headache. I ran
> into this with posix_memalign in some software.
> Although posix_memalign is more modern, If it would be
> trivial to add support for linux specific valloc and
> memalign why not do so as well, to maintain
> compatability with older Linux software. It is better
> to just make FreeBSD be as compatable and for stuff to
> compile out of box, as possible than to haggle over
> conditional ifdefs and changing lines of code in
> software. 
> thank you for your reading these suggestions, it is
> greatly appreciated.
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