* linux/kernel/sched.c: context_switch().
@ 2010-09-08 13:08 fabio de francesco
2010-09-08 13:10 ` chxanders
[not found] ` <201009081518.21569.fabio@metanix.org>
0 siblings, 2 replies; 5+ messages in thread
From: fabio de francesco @ 2010-09-08 13:08 UTC (permalink / raw)
To: LKML
There must be something I am missing in sched.c at context_switch() function
definition.
There I can read the following code:
static inline void
context_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next)
{
...
struct mm_struct *mm;
mm = next->mm;
if (likely(!mm)) {
next->active_mm = oldmm;
atomic_inc(&oldmm->mm_count);
enter_lazy_tlb(oldmm, next);
} else
switch_mm(oldmm, mm, next);
...
}
May someone please explain why the mm pointer is likely supposed to be NULL?
Thanks in advance.
fabio
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: linux/kernel/sched.c: context_switch().
2010-09-08 13:08 linux/kernel/sched.c: context_switch() fabio de francesco
@ 2010-09-08 13:10 ` chxanders
2010-09-08 13:23 ` fabio de francesco
[not found] ` <201009081518.21569.fabio@metanix.org>
1 sibling, 1 reply; 5+ messages in thread
From: chxanders @ 2010-09-08 13:10 UTC (permalink / raw)
To: fabio de francesco; +Cc: LKML
Long day? Do you mean likely(!mm) actually means unlikely(0)?
On 8 September 2010 20:08, fabio de francesco <fabio@metanix.org> wrote:
> There must be something I am missing in sched.c at context_switch() function
> definition.
>
> There I can read the following code:
>
> static inline void
> context_switch(struct rq *rq, struct task_struct *prev,
> struct task_struct *next)
> {
> ...
> struct mm_struct *mm;
> mm = next->mm;
> if (likely(!mm)) {
> next->active_mm = oldmm;
> atomic_inc(&oldmm->mm_count);
> enter_lazy_tlb(oldmm, next);
> } else
> switch_mm(oldmm, mm, next);
> ...
> }
>
> May someone please explain why the mm pointer is likely supposed to be NULL?
>
> Thanks in advance.
>
> fabio
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: linux/kernel/sched.c: context_switch().
2010-09-08 13:10 ` chxanders
@ 2010-09-08 13:23 ` fabio de francesco
0 siblings, 0 replies; 5+ messages in thread
From: fabio de francesco @ 2010-09-08 13:23 UTC (permalink / raw)
To: LKML
On Wednesday 08 September 2010 15:10:49 you wrote:
> Long day? Do you mean likely(!mm) actually means unlikely(0)?
No, no. I am sorry for my poor English. I mean:"likely(!mm)" is like
"likely(0)".
> On 8 September 2010 20:08, fabio de francesco <fabio@metanix.org> wrote:
> > There must be something I am missing in sched.c at context_switch()
> > function definition.
> >
> > There I can read the following code:
> >
> > static inline void
> > context_switch(struct rq *rq, struct task_struct *prev,
> > struct task_struct *next)
> > {
> > ...
> > struct mm_struct *mm;
> > mm = next->mm;
> > if (likely(!mm)) {
> > next->active_mm = oldmm;
> > atomic_inc(&oldmm->mm_count);
> > enter_lazy_tlb(oldmm, next);
> > } else
> > switch_mm(oldmm, mm, next);
> > ...
> > }
> >
> > May someone please explain why the mm pointer is likely supposed to be
> > NULL?
> >
> > Thanks in advance.
> >
> > fabio
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel"
> > in the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: linux/kernel/sched.c: context_switch().
[not found] ` <AANLkTi=mNJhoODzZqLpTC8QqqnwLgWxVXEJzXviF64mV@mail.gmail.com>
@ 2010-09-08 13:54 ` fabio de francesco
0 siblings, 0 replies; 5+ messages in thread
From: fabio de francesco @ 2010-09-08 13:54 UTC (permalink / raw)
To: chxanders, LKML
On Wednesday 08 September 2010 15:22:07 you wrote:
> but there is a ! not operator, !mm means mm != 0 , or the other way it
> is saying it is unlikey(mm is NULL)
Ok. Let me point to Linux-2.6.32. You may see that there the opposite is
written. Can you please explain why they changed unlikely with likely passing
from 2.6.32 to 2.6.33?
> On 8 September 2010 20:18, fabio de francesco <fabio@metanix.org> wrote:
> > On Wednesday 08 September 2010 15:10:49 you wrote:
> >> Long day? Do you mean likely(!mm) actually means unlikely(0)?
> >
> > No, no. I am sorry for my poor English. I mean:"likely(!mm) is like
> > "likely(0)".
> >
> >> On 8 September 2010 20:08, fabio de francesco <fabio@metanix.org> wrote:
> >> > There must be something I am missing in sched.c at context_switch()
> >> > function definition.
> >> >
> >> > There I can read the following code:
> >> >
> >> > static inline void
> >> > context_switch(struct rq *rq, struct task_struct *prev,
> >> > struct task_struct *next)
> >> > {
> >> > ...
> >> > struct mm_struct *mm;
> >> > mm = next->mm;
> >> > if (likely(!mm)) {
> >> > next->active_mm = oldmm;
> >> > atomic_inc(&oldmm->mm_count);
> >> > enter_lazy_tlb(oldmm, next);
> >> > } else
> >> > switch_mm(oldmm, mm, next);
> >> > ...
> >> > }
> >> >
> >> > May someone please explain why the mm pointer is likely supposed to be
> >> > NULL?
> >> >
> >> > Thanks in advance.
> >> >
> >> > fabio
> >> > --
> >> > To unsubscribe from this list: send the line "unsubscribe
> >> > linux-kernel" in the body of a message to majordomo@vger.kernel.org
> >> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> >> > Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 5+ messages in thread
* linux/kernel/sched.c: context_switch().
@ 2010-09-08 12:33 fabio de francesco
0 siblings, 0 replies; 5+ messages in thread
From: fabio de francesco @ 2010-09-08 12:33 UTC (permalink / raw)
To: LKML
There must be something I am missing in sched.c at context_switch() function
definition.
There I can read the following code:
static inline void
context_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next)
{
...
struct mm_struct *mm;
mm = next->mm;
if (likely(!mm)) {
next->active_mm = oldmm;
atomic_inc(&oldmm->mm_count);
enter_lazy_tlb(oldmm, next);
} else
switch_mm(oldmm, mm, next);
...
}
May someone please explain why the mm pointer is likely supposed to be NULL?
Thanks in advance.
fabio
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2010-09-08 13:54 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2010-09-08 13:08 linux/kernel/sched.c: context_switch() fabio de francesco
2010-09-08 13:10 ` chxanders
2010-09-08 13:23 ` fabio de francesco
[not found] ` <201009081518.21569.fabio@metanix.org>
[not found] ` <AANLkTi=mNJhoODzZqLpTC8QqqnwLgWxVXEJzXviF64mV@mail.gmail.com>
2010-09-08 13:54 ` fabio de francesco
-- strict thread matches above, loose matches on Subject: below --
2010-09-08 12:33 fabio de francesco
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.