Some ideas for FreeBSD

millueradfa at millueradfa at
Wed Feb 6 17:50:10 UTC 2008

Dear FreeBSD Developers,

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

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

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

thank you for your reading these suggestions, it is
greatly appreciated.

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