Re: [rfc] Describe events in a structured way via sysfs

From: Johannes Berg <johannes@sipsolutions.net>
To: Lin Ming <ming.m.lin@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	Peter Zijlstra <peterz@infradead.org>, Greg KH <greg@kroah.com>,
	Corey Ashford <cjashfor@linux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Paul Mundt <lethal@linux-sh.org>,
	"eranian@gmail.com" <eranian@gmail.com>,
	"Gary.Mohr@Bull.com" <Gary.Mohr@bull.com>,
	"arjan@linux.intel.com" <arjan@linux.intel.com>,
	"Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
	Paul Mackerras <paulus@samba.org>,
	"David S. Miller" <davem@davemloft.net>,
	Russell King <rmk+kernel@arm.linux.org.uk>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Will Deacon <will.deacon@arm.com>,
	Maynard Johnson <mpjohn@us.ibm.com>, Carl Love <carll@us.ibm.com>,
	Kay Sievers <kay.sievers@vrfy.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [rfc] Describe events in a structured way via sysfs
Date: Tue, 22 Jun 2010 09:39:24 +0200	[thread overview]
Message-ID: <1277192364.3637.10.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <1277192007.3637.8.camel@jlt3.sipsolutions.net>

On Tue, 2010-06-22 at 09:33 +0200, Johannes Berg wrote:

> > > > net/wlan0/events/
> > > > net/waln1/events/
> > > > ....
> > > > net/walnN/events/
> > > 
> > > That's not appropriate either though since you may have multiple network
> > > interfaces on the same hardware :)
> > 
> > Doesn't net/wlan0...wlanN mean multiple network interfaces on the same
> > hardware?
> 
> Yes, but the trace points aren't per network interface but rather per
> hardware piece.

Which really just means that whoever writes the tracepoint needs to
provide a struct device for where to put it (at least in the case of
driver tracepoints), and then ideally some description of the device
also gets put into the ringbuffer.

Assuming you actually want to have the event show up in sysfs twice if
it has multiple producers? I'd like that, it would make sense for a lot
of cases since you might only care about one of the producers.

johannes