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* [PATCH] ftace: remove struct list_head in struct dyn_ftrace
@ 2009-03-13  9:51 Lai Jiangshan
  2009-03-13 10:39 ` [tip:tracing/ftrace] ftrace: remove struct list_head from " Lai Jiangshan
  0 siblings, 1 reply; 6+ messages in thread
From: Lai Jiangshan @ 2009-03-13  9:51 UTC (permalink / raw)
  To: Steven Rostedt, Ingo Molnar, LKML


Impact: save memory

The struct dyn_ftrace table is very large, this patch will save about
50%

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index e1583f2..4dc32c8 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -145,7 +145,6 @@ enum {
 };
 
 struct dyn_ftrace {
-	struct list_head	list;
 	unsigned long		ip; /* address of mcount call-site */
 	unsigned long		flags;
 	struct dyn_arch_ftrace	arch;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d33d306..40eaaae 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -272,7 +272,7 @@ enum {
 
 static int ftrace_filtered;
 
-static LIST_HEAD(ftrace_new_addrs);
+static struct dyn_ftrace *ftrace_new_addrs;
 
 static DEFINE_MUTEX(ftrace_regex_lock);
 
@@ -408,8 +408,8 @@ ftrace_record_ip(unsigned long ip)
 		return NULL;
 
 	rec->ip = ip;
-
-	list_add(&rec->list, &ftrace_new_addrs);
+	rec->flags = (unsigned long)ftrace_new_addrs;
+	ftrace_new_addrs = rec;
 
 	return rec;
 }
@@ -714,19 +714,21 @@ unsigned long		ftrace_update_tot_cnt;
 
 static int ftrace_update_code(struct module *mod)
 {
-	struct dyn_ftrace *p, *t;
+	struct dyn_ftrace *p;
 	cycle_t start, stop;
 
 	start = ftrace_now(raw_smp_processor_id());
 	ftrace_update_cnt = 0;
 
-	list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) {
+	while (ftrace_new_addrs) {
 
 		/* If something went wrong, bail without enabling anything */
 		if (unlikely(ftrace_disabled))
 			return -1;
 
-		list_del_init(&p->list);
+		p = ftrace_new_addrs;
+		ftrace_new_addrs = (struct dyn_ftrace *)p->flags;
+		p->flags = 0L;
 
 		/* convert record (i.e, patch mcount-call with NOP) */
 		if (ftrace_code_disable(mod, p)) {



^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [tip:tracing/ftrace] ftrace: remove struct list_head from struct dyn_ftrace
  2009-03-13  9:51 [PATCH] ftace: remove struct list_head in struct dyn_ftrace Lai Jiangshan
@ 2009-03-13 10:39 ` Lai Jiangshan
  2009-03-13 13:16   ` Steven Rostedt
  2009-03-16 12:36   ` Frederic Weisbecker
  0 siblings, 2 replies; 6+ messages in thread
From: Lai Jiangshan @ 2009-03-13 10:39 UTC (permalink / raw)
  To: linux-tip-commits; +Cc: linux-kernel, hpa, mingo, srostedt, tglx, laijs, mingo

Commit-ID:  e94142a67f8bad494c593f0a07c9fc2fbec98c0e
Gitweb:     http://git.kernel.org/tip/e94142a67f8bad494c593f0a07c9fc2fbec98c0e
Author:     Lai Jiangshan <laijs@cn.fujitsu.com>
AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800
Commit:     Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 13 Mar 2009 11:36:20 +0100

ftrace: remove struct list_head from struct dyn_ftrace

Impact: save memory

The struct dyn_ftrace table is very large, this patch will save
about 50%.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49BA2C9F.8020009@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 include/linux/ftrace.h |    1 -
 kernel/trace/ftrace.c  |   14 ++++++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index c146c10..9d598bb 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -145,7 +145,6 @@ enum {
 };
 
 struct dyn_ftrace {
-	struct list_head	list;
 	unsigned long		ip; /* address of mcount call-site */
 	unsigned long		flags;
 	struct dyn_arch_ftrace	arch;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index bf78a4c..90d5729 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -272,7 +272,7 @@ enum {
 
 static int ftrace_filtered;
 
-static LIST_HEAD(ftrace_new_addrs);
+static struct dyn_ftrace *ftrace_new_addrs;
 
 static DEFINE_MUTEX(ftrace_regex_lock);
 
@@ -409,8 +409,8 @@ ftrace_record_ip(unsigned long ip)
 		return NULL;
 
 	rec->ip = ip;
-
-	list_add(&rec->list, &ftrace_new_addrs);
+	rec->flags = (unsigned long)ftrace_new_addrs;
+	ftrace_new_addrs = rec;
 
 	return rec;
 }
@@ -716,19 +716,21 @@ unsigned long		ftrace_update_tot_cnt;
 
 static int ftrace_update_code(struct module *mod)
 {
-	struct dyn_ftrace *p, *t;
+	struct dyn_ftrace *p;
 	cycle_t start, stop;
 
 	start = ftrace_now(raw_smp_processor_id());
 	ftrace_update_cnt = 0;
 
-	list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) {
+	while (ftrace_new_addrs) {
 
 		/* If something went wrong, bail without enabling anything */
 		if (unlikely(ftrace_disabled))
 			return -1;
 
-		list_del_init(&p->list);
+		p = ftrace_new_addrs;
+		ftrace_new_addrs = (struct dyn_ftrace *)p->flags;
+		p->flags = 0L;
 
 		/* convert record (i.e, patch mcount-call with NOP) */
 		if (ftrace_code_disable(mod, p)) {

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [tip:tracing/ftrace] ftrace: remove struct list_head from struct dyn_ftrace
  2009-03-13 10:39 ` [tip:tracing/ftrace] ftrace: remove struct list_head from " Lai Jiangshan
@ 2009-03-13 13:16   ` Steven Rostedt
  2009-03-16 12:36   ` Frederic Weisbecker
  1 sibling, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2009-03-13 13:16 UTC (permalink / raw)
  To: mingo, hpa, linux-kernel, tglx, laijs, mingo; +Cc: linux-tip-commits


On Fri, 2009-03-13 at 10:39 +0000, Lai Jiangshan wrote:
> Commit-ID:  e94142a67f8bad494c593f0a07c9fc2fbec98c0e
> Gitweb:     http://git.kernel.org/tip/e94142a67f8bad494c593f0a07c9fc2fbec98c0e
> Author:     Lai Jiangshan <laijs@cn.fujitsu.com>
> AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800
> Commit:     Ingo Molnar <mingo@elte.hu>
> CommitDate: Fri, 13 Mar 2009 11:36:20 +0100
> 
> ftrace: remove struct list_head from struct dyn_ftrace
> Impact: save memory
> 
> The struct dyn_ftrace table is very large, this patch will save
> about 50%.
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> Cc: Steven Rostedt <srostedt@redhat.com>
> LKML-Reference: <49BA2C9F.8020009@cn.fujitsu.com>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> 
> 
> ---
>  include/linux/ftrace.h |    1 -
>  kernel/trace/ftrace.c  |   14 ++++++++------
>  2 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index c146c10..9d598bb 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -145,7 +145,6 @@ enum {
>  };
>  
>  struct dyn_ftrace {
> -	struct list_head	list;
>  	unsigned long		ip; /* address of mcount call-site */
>  	unsigned long		flags;
>  	struct dyn_arch_ftrace	arch;
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index bf78a4c..90d5729 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -272,7 +272,7 @@ enum {
>  
>  static int ftrace_filtered;
>  
> -static LIST_HEAD(ftrace_new_addrs);
> +static struct dyn_ftrace *ftrace_new_addrs;
>  
>  static DEFINE_MUTEX(ftrace_regex_lock);
>  
> @@ -409,8 +409,8 @@ ftrace_record_ip(unsigned long ip)
>  		return NULL;
>  
>  	rec->ip = ip;
> -
> -	list_add(&rec->list, &ftrace_new_addrs);
> +	rec->flags = (unsigned long)ftrace_new_addrs;

Lets not play games with pointers. If we are going to do this, make it
into a union.

struct dyn_arch_ftrace {
	unsigned long ip;
	union {
		unsigned long flags;
		struct dyn_arch_ftrace *next;
	}
	struct dyn_arch_ftrace arch;
};


This way it is much clearer to what is going on.


> +	ftrace_new_addrs = rec;
>  
>  	return rec;
>  }
> @@ -716,19 +716,21 @@ unsigned long		ftrace_update_tot_cnt;
>  
>  static int ftrace_update_code(struct module *mod)
>  {
> -	struct dyn_ftrace *p, *t;
> +	struct dyn_ftrace *p;
>  	cycle_t start, stop;
>  
>  	start = ftrace_now(raw_smp_processor_id());
>  	ftrace_update_cnt = 0;
>  
> -	list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) {
> +	while (ftrace_new_addrs) {
>  
>  		/* If something went wrong, bail without enabling anything */
>  		if (unlikely(ftrace_disabled))
>  			return -1;
>  
> -		list_del_init(&p->list);
> +		p = ftrace_new_addrs;
> +		ftrace_new_addrs = (struct dyn_ftrace *)p->flags;

This confused me (and scared me) for a bit. Having a union would not
have.

Make the change to a union, and then you have my:

Acked-by: Steven Rostedt <srostedt@redhat.com>

Thanks,

-- Steve



> +		p->flags = 0L;
>  
>  		/* convert record (i.e, patch mcount-call with NOP) */
>  		if (ftrace_code_disable(mod, p)) {


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [tip:tracing/ftrace] ftrace: remove struct list_head from struct dyn_ftrace
  2009-03-13 10:39 ` [tip:tracing/ftrace] ftrace: remove struct list_head from " Lai Jiangshan
  2009-03-13 13:16   ` Steven Rostedt
@ 2009-03-16 12:36   ` Frederic Weisbecker
  2009-03-16 12:42     ` Frederic Weisbecker
  1 sibling, 1 reply; 6+ messages in thread
From: Frederic Weisbecker @ 2009-03-16 12:36 UTC (permalink / raw)
  To: mingo, hpa, linux-kernel, srostedt, tglx, laijs, mingo; +Cc: linux-tip-commits

On Fri, Mar 13, 2009 at 10:39:36AM +0000, Lai Jiangshan wrote:
> Commit-ID:  e94142a67f8bad494c593f0a07c9fc2fbec98c0e
> Gitweb:     http://git.kernel.org/tip/e94142a67f8bad494c593f0a07c9fc2fbec98c0e
> Author:     Lai Jiangshan <laijs@cn.fujitsu.com>
> AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800
> Commit:     Ingo Molnar <mingo@elte.hu>
> CommitDate: Fri, 13 Mar 2009 11:36:20 +0100
> 
> ftrace: remove struct list_head from struct dyn_ftrace
> 
> Impact: save memory
> 
> The struct dyn_ftrace table is very large, this patch will save
> about 50%.
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> Cc: Steven Rostedt <srostedt@redhat.com>
> LKML-Reference: <49BA2C9F.8020009@cn.fujitsu.com>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> 
> 
> ---
>  include/linux/ftrace.h |    1 -
>  kernel/trace/ftrace.c  |   14 ++++++++------
>  2 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index c146c10..9d598bb 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -145,7 +145,6 @@ enum {
>  };
>  
>  struct dyn_ftrace {
> -	struct list_head	list;
>  	unsigned long		ip; /* address of mcount call-site */
>  	unsigned long		flags;
>  	struct dyn_arch_ftrace	arch;
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index bf78a4c..90d5729 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -272,7 +272,7 @@ enum {
>  
>  static int ftrace_filtered;
>  
> -static LIST_HEAD(ftrace_new_addrs);
> +static struct dyn_ftrace *ftrace_new_addrs;
>  
>  static DEFINE_MUTEX(ftrace_regex_lock);
>  
> @@ -409,8 +409,8 @@ ftrace_record_ip(unsigned long ip)
>  		return NULL;
>  
>  	rec->ip = ip;
> -
> -	list_add(&rec->list, &ftrace_new_addrs);
> +	rec->flags = (unsigned long)ftrace_new_addrs;
> +	ftrace_new_addrs = rec;


But... you are overwritting all the ftrace flags infrastructure by
using it as a list pointer.

This is breaking dynamic tracing.

>  
>  	return rec;
>  }
> @@ -716,19 +716,21 @@ unsigned long		ftrace_update_tot_cnt;
>  
>  static int ftrace_update_code(struct module *mod)
>  {
> -	struct dyn_ftrace *p, *t;
> +	struct dyn_ftrace *p;
>  	cycle_t start, stop;
>  
>  	start = ftrace_now(raw_smp_processor_id());
>  	ftrace_update_cnt = 0;
>  
> -	list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) {
> +	while (ftrace_new_addrs) {
>  
>  		/* If something went wrong, bail without enabling anything */
>  		if (unlikely(ftrace_disabled))
>  			return -1;
>  
> -		list_del_init(&p->list);
> +		p = ftrace_new_addrs;
> +		ftrace_new_addrs = (struct dyn_ftrace *)p->flags;
> +		p->flags = 0L;
>  
>  		/* convert record (i.e, patch mcount-call with NOP) */
>  		if (ftrace_code_disable(mod, p)) {
> --
> To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [tip:tracing/ftrace] ftrace: remove struct list_head from struct dyn_ftrace
  2009-03-16 12:36   ` Frederic Weisbecker
@ 2009-03-16 12:42     ` Frederic Weisbecker
  2009-03-18  2:50       ` Lai Jiangshan
  0 siblings, 1 reply; 6+ messages in thread
From: Frederic Weisbecker @ 2009-03-16 12:42 UTC (permalink / raw)
  To: mingo, hpa, linux-kernel, srostedt, tglx, laijs, mingo; +Cc: linux-tip-commits

On Mon, Mar 16, 2009 at 01:36:09PM +0100, Frederic Weisbecker wrote:
> On Fri, Mar 13, 2009 at 10:39:36AM +0000, Lai Jiangshan wrote:
> > Commit-ID:  e94142a67f8bad494c593f0a07c9fc2fbec98c0e
> > Gitweb:     http://git.kernel.org/tip/e94142a67f8bad494c593f0a07c9fc2fbec98c0e
> > Author:     Lai Jiangshan <laijs@cn.fujitsu.com>
> > AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800
> > Commit:     Ingo Molnar <mingo@elte.hu>
> > CommitDate: Fri, 13 Mar 2009 11:36:20 +0100
> > 
> > ftrace: remove struct list_head from struct dyn_ftrace
> > 
> > Impact: save memory
> > 
> > The struct dyn_ftrace table is very large, this patch will save
> > about 50%.
> > 
> > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> > Cc: Steven Rostedt <srostedt@redhat.com>
> > LKML-Reference: <49BA2C9F.8020009@cn.fujitsu.com>
> > Signed-off-by: Ingo Molnar <mingo@elte.hu>
> > 
> > 
> > ---
> >  include/linux/ftrace.h |    1 -
> >  kernel/trace/ftrace.c  |   14 ++++++++------
> >  2 files changed, 8 insertions(+), 7 deletions(-)
> > 
> > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> > index c146c10..9d598bb 100644
> > --- a/include/linux/ftrace.h
> > +++ b/include/linux/ftrace.h
> > @@ -145,7 +145,6 @@ enum {
> >  };
> >  
> >  struct dyn_ftrace {
> > -	struct list_head	list;
> >  	unsigned long		ip; /* address of mcount call-site */
> >  	unsigned long		flags;
> >  	struct dyn_arch_ftrace	arch;
> > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > index bf78a4c..90d5729 100644
> > --- a/kernel/trace/ftrace.c
> > +++ b/kernel/trace/ftrace.c
> > @@ -272,7 +272,7 @@ enum {
> >  
> >  static int ftrace_filtered;
> >  
> > -static LIST_HEAD(ftrace_new_addrs);
> > +static struct dyn_ftrace *ftrace_new_addrs;
> >  
> >  static DEFINE_MUTEX(ftrace_regex_lock);
> >  
> > @@ -409,8 +409,8 @@ ftrace_record_ip(unsigned long ip)
> >  		return NULL;
> >  
> >  	rec->ip = ip;
> > -
> > -	list_add(&rec->list, &ftrace_new_addrs);
> > +	rec->flags = (unsigned long)ftrace_new_addrs;
> > +	ftrace_new_addrs = rec;
> 
> 
> But... you are overwritting all the ftrace flags infrastructure by
> using it as a list pointer.
> 
> This is breaking dynamic tracing.


May be I'm wrong. May be I misunderstood this patch.
But I don't understand how flags can be used at the same time as a pointer
and as a flag value.

 
> >  
> >  	return rec;
> >  }
> > @@ -716,19 +716,21 @@ unsigned long		ftrace_update_tot_cnt;
> >  
> >  static int ftrace_update_code(struct module *mod)
> >  {
> > -	struct dyn_ftrace *p, *t;
> > +	struct dyn_ftrace *p;
> >  	cycle_t start, stop;
> >  
> >  	start = ftrace_now(raw_smp_processor_id());
> >  	ftrace_update_cnt = 0;
> >  
> > -	list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) {
> > +	while (ftrace_new_addrs) {
> >  
> >  		/* If something went wrong, bail without enabling anything */
> >  		if (unlikely(ftrace_disabled))
> >  			return -1;
> >  
> > -		list_del_init(&p->list);
> > +		p = ftrace_new_addrs;
> > +		ftrace_new_addrs = (struct dyn_ftrace *)p->flags;
> > +		p->flags = 0L;
> >  
> >  		/* convert record (i.e, patch mcount-call with NOP) */
> >  		if (ftrace_code_disable(mod, p)) {
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [tip:tracing/ftrace] ftrace: remove struct list_head from struct dyn_ftrace
  2009-03-16 12:42     ` Frederic Weisbecker
@ 2009-03-18  2:50       ` Lai Jiangshan
  0 siblings, 0 replies; 6+ messages in thread
From: Lai Jiangshan @ 2009-03-18  2:50 UTC (permalink / raw)
  To: Frederic Weisbecker
  Cc: mingo, hpa, linux-kernel, srostedt, tglx, mingo, linux-tip-commits

Frederic Weisbecker wrote:
> 
> 
> May be I'm wrong. May be I misunderstood this patch.
> But I don't understand how flags can be used at the same time as a pointer
> and as a flag value.
> 

When a new dyn_ftrace is added to ftrace_new_addrs list, the flag is 0,
it's always 0 until this dyn_ftrace is removed from the list, so we can
reuse the flag field. As Steven's suggest, using an union is better.

ftrace_convert_nops()
  ftrace_record_ip() // allocate dyn_ftrace, and add it
                     // to ftrace_new_addrs list
  ftrace_update_code() // remove it from ftrace_new_addrs.

Lai.


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2009-03-18  2:51 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-03-13  9:51 [PATCH] ftace: remove struct list_head in struct dyn_ftrace Lai Jiangshan
2009-03-13 10:39 ` [tip:tracing/ftrace] ftrace: remove struct list_head from " Lai Jiangshan
2009-03-13 13:16   ` Steven Rostedt
2009-03-16 12:36   ` Frederic Weisbecker
2009-03-16 12:42     ` Frederic Weisbecker
2009-03-18  2:50       ` Lai Jiangshan

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