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Subject: Re: Unified tracing buffer
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Martin Bligh <mbligh@google.com>
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       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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Date: Mon, 22 Sep 2008 18:36:41 +0200
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On Mon, 2008-09-22 at 09:29 -0700, Martin Bligh wrote:
> >> In conjunction with the previous email on this thread
> >> (http://lkml.org/lkml/2008/9/22/160), may I suggest
> >> the equivalent interfaces in -mm tree (2.6.27-rc5-mm1) to be:
> >>
> >> relay_printk(<some struct with default filenames/pathnames>, <string>,
> >> ....) ;
> >> relay_dump(<some struct with default filenames/pathnames>, <binary
> >> data>);
> >> and
> >> relay_cleanup_all(<the struct name>); - Single interface that cleans up
> >> all files/directories/output data created under a logical entity.
> >
> > Dude, relayfs is such a bad performing mess that extending it seems like
> > a bad idea. Better to write something new and delete everything relayfs
> > related.
> 
> There did seem to be pretty universal agreement that we'd rather not
> use relayfs.
> 
> > Also, it seems prudent to separate the ring-buffer implementation from
> > the event encoding/decoding facilities.
> 
> Right - in conversation I had with Mathieu later, he suggested cleaning up
> relayfs - I fear this will delay us far too long, and get bogged down.
> If we can get one clean circular buffer implementation, then both
> relayfs and the tracing could share that common solution,

Currently only blktrace and kvmtrace use relayfs, and I've heard people
talk about converting both to use lttng/ftrace infrastructure. At which
point relayfs is orphaned and ready for removal.