MFS question - FreeBSD 5.2-CURRENT

[Peter Jeremy]

On Thu, Jan 22, 2004 at 09:16:14PM +0000, Rob MacGregor wrote:
>>Note that softupdates will not perform any physical writes for short-
>>lived (say less than 30 seconds) files.
>
>That's worth knowing - do you know how big the buffer is likely to be?  I'm 
>thinking worst case of a 10 MB zip in an email, maybe expanding to 20 MB.

As someone else mentioned, there is no fixed size.  The kernel will
allocate RAM to the buffer as well as running processes.  For some
background on softupdates, have a look at:

Gregory R. Ganger's original paper on SoftUpdates:
http://www.ece.cmu.edu/~ganger/papers/CSE-TR-254-95/

Kirk McKusick's papers on SoftUpdates (which discusses the FreeBSD
implementation:
http://www.mckusick.com/softdep/index.html

Peter