Impact: save memory
The struct dyn_ftrace table is very large, this patch will save about
50%
Signed-off-by: Lai Jiangshan <[email protected]>
---
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)) {
Commit-ID: e94142a67f8bad494c593f0a07c9fc2fbec98c0e
Gitweb: http://git.kernel.org/tip/e94142a67f8bad494c593f0a07c9fc2fbec98c0e
Author: Lai Jiangshan <[email protected]>
AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800
Commit: Ingo Molnar <[email protected]>
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 <[email protected]>
Cc: Steven Rostedt <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
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)) {
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 <[email protected]>
> AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800
> Commit: Ingo Molnar <[email protected]>
> 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 <[email protected]>
> Cc: Steven Rostedt <[email protected]>
> LKML-Reference: <[email protected]>
> Signed-off-by: Ingo Molnar <[email protected]>
>
>
> ---
> 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 <[email protected]>
Thanks,
-- Steve
> + p->flags = 0L;
>
> /* convert record (i.e, patch mcount-call with NOP) */
> if (ftrace_code_disable(mod, p)) {
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 <[email protected]>
> AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800
> Commit: Ingo Molnar <[email protected]>
> 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 <[email protected]>
> Cc: Steven Rostedt <[email protected]>
> LKML-Reference: <[email protected]>
> Signed-off-by: Ingo Molnar <[email protected]>
>
>
> ---
> 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 [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
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 <[email protected]>
> > AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800
> > Commit: Ingo Molnar <[email protected]>
> > 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 <[email protected]>
> > Cc: Steven Rostedt <[email protected]>
> > LKML-Reference: <[email protected]>
> > Signed-off-by: Ingo Molnar <[email protected]>
> >
> >
> > ---
> > 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 [email protected]
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>
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.