Greg KH wrote: > On Fri, Nov 04, 2005 at 09:34:20AM -0800, Tim Bird wrote: > >>I have trace data that I export to user space via procfs, using >>seq_file operations. I copied this technique from Ingo Molnar's >>code to trace preemption issues, and it has been working well >>for my tracing system. >> >>Patches are available at: >>http://tree.celinuxforum.org/CelfPubWiki/KernelFunctionTrace >>(follow the link under Downloads to the CELF patch archive, >>and look for kft-all-in-one-2.6.12.patch. Sorry, patches >>for later kernels are not available yet.) > > For later kernels, you should use relayfs, as this is exactly what it > was made for. Hm, I think there is a trace patch for this exact reason > that uses relayfs too :) > I've been waiting for relayfs to stabilize and get mainlined. Now that it has, I'll take a look at it again. One thing that didn't work for me before was that it ONLY supported per-cpu buffering. I prefer a single buffer (I know it causes cache thrashing, but I have my reasons). Also, having to mount it is really a pain. > > Please please please do not abuse procfs for this kind of thing anymore, > we are _really_ trying to clean this stuff up and even with > out-of-the-tree patches like this, it sends the wrong message (and > people copy code for this stuff from everywhere...) Like I did from Ingo? Sheesh, I thought he was a reliable source. ;-) I agree proliferation of the wrong thing is bad. I realized I had a lot of cleanup work to do before submitting my own tracing thing to mainline, which is why I've never sent it in. But we've been using it at Sony for years now and it's proven very useful. I'm about to start work on 2.6.14 myself, so I'll check out the status of relayfs and see if I can make it work for me. I hate to replace a very simple system that's working for me with a complicated one that doesn't quite, though. As an aside, what trace patch that uses relayfs are you referring - an updated LTT or something else? There appear to be no in-kernel users of relayfs to use for an example. Thanks, -- Tim ============================= Tim Bird Architecture Group Chair, CE Linux Forum Senior Staff Engineer, Sony Electronics ============================= -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
