Re: Minutes of 6/2/05 meeting

[Karim Yaghmour <karim at opersys dot com>]

Jim Keniston wrote:
> Martin has been working on runtime support for aggregations and
> statistics.  He has not yet done any relayfs-vs.-netlink performance
> testing.

Note that there are authors of the netlink RFC that readily acknowledge
that netlink and relayfs serve very different purposes. Such a
comparison entertains a confusion which has been dissipated quite some
time ago.

Here's a direct quote from Andi Kleen back when Andrew first put relayfs
in 2.6.11-rc1-mm1:
> imho relayfs and netlink are for completely problem spaces.
> relayfs is for relaying a lot of data quickly (e.g. for kernel
> instrumentation). There it fills a niche that printk doesn't fill
> (since it's too slow). netlink is quite slow (allocates data for each
> event, does lots of other gunk), but an useful extensible format
> for low frequency events.

Andi then goes on to list a couple of things he thinks need to be
fixed with relayfs. Since then, these things have been fixed thanks
to Tom Zanussi's continued work.

Original found here:
http://marc.theaimsgroup.com/?l=linux-kernel&m=110569261401528&w=2

At present, ltt is using relayfs, but it will also use netlink in
order to replace all the kernel/user-space communication which is
currently implemented in all sorts of ways which are not very
elegant (/proc, ioctls, etc.)

Best regards,

Karim
-- 
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