many small messages over kdbus

[Lennart Poettering]

On Mon, 12.05.14 10:53, Urs Fässler (urs at bytesatwork.ch) wrote:

> Hi all,
> I need an IPC system which supports broadcasts. It would be nice if we
> can send many small messages (~64 bytes every 5 ms to ~12 receiver).
> 
> On a BeagleBone @ 720 MHz (Linux 3.12, kdbus e62195ac as module) I get
> nearly 100% CPU usage with the mentioned setup. Most time is spent in
> kdbus, allocating and zeroing pages to deliver messages.
> 
> Now my questions are:
> 1. Are my results sane?
> 2. Is this a sane usage of kdbus or a kind of stupid idea?
> 3. Is it possible that the receiver provides a buffer for the messages,
>    so that no allocation and zeroing is needed (or is it planned /
>    welcome if someone implements it)?

Well, the receiver owns and maps the buffer. The kernel then allocates
sections within it, and writes to it.

Please send queries regarding kdbus to the systemd ML.

Lennart

-- 
Lennart Poettering, Red Hat