22 Jun
2009
22 Jun
'09
1:50 p.m.
On Mon, 22.06.09 16:34, Adam Sampson (ats(a)offog.org) wrote:
No.
rtkit is just an option. If distros install it, then you can use
it. If they don't then don't. The reference client code will magically
start to work if rtkit is around. If it isn't then there's still
RLIMIT_RTPRIO.
Really, there is no dependency.
The reference implementation is relatively verbose, because it is
... a reference implementation. You can implement the real-time method
invocation in one call to dbus_message_new_method_call() followed by
dbus_message_append_args(), followed by
dbus_connection_send_with_reply_and_block(). Done.
There is not
compile time dependency on rtkit and no runtime
dependency either.
Yes, there is a runtime dependency on RealtimeKit -- else there would be
no point in having it in the first place! If I'm building an operating
system package for an application that wants realtime priority, then my
package has to have an explicit dependency on RealtimeKit as well as
D-Bus. Also, the
client reference implementation is tiny. it just wraps two
method calls. Trivial stuff.
It's neither trivial nor tiny -- rtkit.c is a bit over a hundred
non-comment/blank lines of code. The entirety of thread.c in libjack
(which handles getting realtime priority on a variety of operating
systems, among other things) is less than two hundred. This should be in
a library, *not* copied-and-pasted into multiple places; that's a
maintenance nightmare waiting to happen. I should be clearer here that I think the RealtimeKit
approach is
actually pretty sensible on Linux, and I don't have any objections to
using D-Bus. I just think it's important to recognise that this approach
is not appropriate for all platforms, and providing a more conventional
library interface would be more convenient for programmers, more
portable, and generally better software engineering practice.
I guess we have to agree to disagree here then.
Lennart
--
Lennart Poettering Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/ GnuPG 0x1A015CC4