Date:	Fri, 6 Mar 2009 13:41:05 -0500 (EST)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	ltt-dev@...ts.casi.polymtl.ca,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Arjan van de Ven <arjan@...radead.org>,
	Pekka Paalanen <pq@....fi>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Martin Bligh <mbligh@...gle.com>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	Tom Zanussi <tzanussi@...il.com>,
	Masami Hiramatsu <mhiramat@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Jason Baron <jbaron@...hat.com>,
	Christoph Hellwig <hch@...radead.org>,
	Jiaying Zhang <jiayingz@...gle.com>,
	Eduard - Gabriel Munteanu <eduard.munteanu@...ux360.ro>,
	mrubin@...gle.com, md@...gle.com
Subject: Re: [RFC patch 02/41] LTTng - core data structures



On Thu, 5 Mar 2009, Mathieu Desnoyers wrote:

> Home of the traces data structures. Needs to be built into the kernel.
> 
> LTT heartbeat is a module specialized into firing periodical interrupts to
> record events in traces (so cycle counter rollover can be detected) and to
> update the 64 bits "synthetic TSC" (extended from the CPU 32 bits TSC on MIPS).
> Also needs to be built into the kernel.

Why is patch 1 and 2 separate. They look like they should be a single 
patch. Patch 1 is pretty useless by itself. This patch depends on patch 1.

-- Steve



> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
> ---
>  MAINTAINERS              |    7 +++
>  include/linux/ltt-core.h |   10 ++++
>  ltt/ltt-core.c           |  101 +++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 118 insertions(+)
> 
> Index: linux-2.6-lttng/MAINTAINERS
> ===================================================================
> --- linux-2.6-lttng.orig/MAINTAINERS	2009-03-04 13:24:38.000000000 -0500
> +++ linux-2.6-lttng/MAINTAINERS	2009-03-04 13:24:59.000000000 -0500
> @@ -2766,6 +2766,13 @@ P:	Eric Piel
>  M:	eric.piel@...mplin-utc.net
>  S:	Maintained
>  
> +LINUX TRACE TOOLKIT NEXT GENERATION
> +P:	Mathieu Desnoyers
> +M:	mathieu.desnoyers@...ymtl.ca
> +L:	ltt-dev@...ng.org
> +W:	http://ltt.polymtl.ca
> +S:	Maintained
> +
>  LM83 HARDWARE MONITOR DRIVER
>  P:	Jean Delvare
>  M:	khali@...ux-fr.org
> Index: linux-2.6-lttng/ltt/ltt-core.c
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ linux-2.6-lttng/ltt/ltt-core.c	2009-03-04 13:36:17.000000000 -0500
> @@ -0,0 +1,101 @@
> +/*
> + * LTT core in-kernel infrastructure.
> + *
> + * Copyright 2006 - Mathieu Desnoyers mathieu.desnoyers@...ymtl.ca
> + *
> + * Distributed under the GPL license
> + */
> +
> +#include <linux/ltt-core.h>
> +#include <linux/percpu.h>
> +#include <linux/module.h>
> +#include <linux/debugfs.h>
> +#include <linux/kref.h>
> +
> +/* Traces structures */
> +struct ltt_traces ltt_traces = {
> +	.setup_head = LIST_HEAD_INIT(ltt_traces.setup_head),
> +	.head = LIST_HEAD_INIT(ltt_traces.head),
> +};
> +EXPORT_SYMBOL(ltt_traces);
> +
> +/* Traces list writer locking */
> +static DEFINE_MUTEX(ltt_traces_mutex);
> +
> +/* root dentry mutex */
> +static DEFINE_MUTEX(ltt_root_mutex);
> +/* dentry of ltt's root dir */
> +static struct dentry *ltt_root_dentry;
> +static struct kref ltt_root_kref = {
> +	.refcount = ATOMIC_INIT(0),
> +};
> +
> +static void ltt_root_release(struct kref *ref)
> +{
> +	debugfs_remove(ltt_root_dentry);
> +	ltt_root_dentry = NULL;
> +}
> +
> +void put_ltt_root(void)
> +{
> +	mutex_lock(&ltt_root_mutex);
> +	if (ltt_root_dentry)
> +		kref_put(&ltt_root_kref, ltt_root_release);
> +	mutex_unlock(&ltt_root_mutex);
> +}
> +EXPORT_SYMBOL_GPL(put_ltt_root);
> +
> +struct dentry *get_ltt_root(void)
> +{
> +	mutex_lock(&ltt_root_mutex);
> +	if (!ltt_root_dentry) {
> +		ltt_root_dentry = debugfs_create_dir(LTT_ROOT, NULL);
> +		if (!ltt_root_dentry) {
> +			printk(KERN_ERR "LTT : create ltt root dir failed\n");
> +			goto out;
> +		}
> +		kref_init(&ltt_root_kref);
> +		goto out;
> +	}
> +	kref_get(&ltt_root_kref);
> +out:
> +	mutex_unlock(&ltt_root_mutex);
> +	return ltt_root_dentry;
> +}
> +EXPORT_SYMBOL_GPL(get_ltt_root);
> +
> +void ltt_lock_traces(void)
> +{
> +	mutex_lock(&ltt_traces_mutex);
> +}
> +EXPORT_SYMBOL_GPL(ltt_lock_traces);
> +
> +void ltt_unlock_traces(void)
> +{
> +	mutex_unlock(&ltt_traces_mutex);
> +}
> +EXPORT_SYMBOL_GPL(ltt_unlock_traces);
> +
> +DEFINE_PER_CPU(unsigned int, ltt_nesting);
> +EXPORT_PER_CPU_SYMBOL(ltt_nesting);
> +
> +int ltt_run_filter_default(void *trace, uint16_t eID)
> +{
> +	return 1;
> +}
> +
> +/* This function pointer is protected by a trace activation check */
> +ltt_run_filter_functor ltt_run_filter = ltt_run_filter_default;
> +EXPORT_SYMBOL_GPL(ltt_run_filter);
> +
> +void ltt_filter_register(ltt_run_filter_functor func)
> +{
> +	ltt_run_filter = func;
> +}
> +EXPORT_SYMBOL_GPL(ltt_filter_register);
> +
> +void ltt_filter_unregister(void)
> +{
> +	ltt_run_filter = ltt_run_filter_default;
> +}
> +EXPORT_SYMBOL_GPL(ltt_filter_unregister);
> 
> -- 
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> 
--
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