Using INN with shared writable memory in Linux 1.3.3

Brian Blackmore (
24 Jun 1995 20:46:00 +0100

Linus did say a while back that he would like somebody brave to try
out using INN with shared writable memory mappings and since I run INN
for my own purposes and my own purposes only I thought I'd give it a
try. I present the following observations which may or may not be of
interest to Linus and anyone else reading here..

1. With shared memory creating new groups doesn't seem to work properly,
all you get in the active file is the approprate number of NUL's at the
end. I remember Linus saying he wasn't quite sure what to do when you
ran off the end of the mapping, well INN seems to want to extend it,
Linux at present doesn't.

2. It takes too long to update the active file from the copy in memory, we
seem to need an msync or the availablity of a syncronus (sp?) mapping. I
couldn't find anything that looked like msync in libc or a system call in
the kernel (although I wasn't really sure what to look for).