Re: Help with netlink needed

[Tom Zanussi <zanussi at us dot ibm dot com>]

Martin Hunt writes:
 > We really need to start getting the kernel <-> user space data transport
 > code into the runtime library soon.  I have not done any work with this,
 > so help would be greatly appreciated.
 > 
 > We have several immediate requirements:
 > 
 > 1. High-speed transfer of large amounts of collected data.  I was
 > thinking of having 2 large trace buffers, one active and one inactive.
 > When the active one fills up, it is marked inactive and a task is put on
 > the work queue to send it.  The inactive buffer becomes active and will
 > be used while the inactive one is written to user-space. A command could
 > also be provided to flush the active buffer.
 > 
 > 2. A separate channel for immediate messages.  Used to signal error
 > conditions, print warnings, etc.  Anything that is not normal trace
 > output.
 > 
 > Any thoughts? Code?

relayfs might be useful for 1), depending on how much data you
typically have to send to user space - it's sort of tailored for
applications that need to large amounts of data.  It definitely
wouldn't be good for 2).  The latest version of relayfs is in the -mm
tree, and there are example applications and documention here:

http://prdownloads.sourceforge.net/dprobes/relay-apps-0.2.tar.gz?download

Tom