From: Shan Wei <[email protected]>
Signed-off-by: Shan Wei <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
---
no changes vs v3,v2.
---
kernel/rcutree.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 74df86b..441b945 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1960,7 +1960,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
struct rcu_node *rnp_old = NULL;
/* Funnel through hierarchy to reduce memory contention. */
- rnp = per_cpu_ptr(rsp->rda, raw_smp_processor_id())->mynode;
+ rnp = __this_cpu_read(rsp->rda->mynode);
for (; rnp != NULL; rnp = rnp->parent) {
ret = (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) ||
!raw_spin_trylock(&rnp->fqslock);
--
1.7.1
Shan Wei said, at 2012/11/13 9:52:
> From: Shan Wei <[email protected]>
>
> Signed-off-by: Shan Wei <[email protected]>
> Acked-by: Christoph Lameter <[email protected]>
Paul, would you like to pick it up to your tree?
> ---
> no changes vs v3,v2.
> ---
> kernel/rcutree.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 74df86b..441b945 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -1960,7 +1960,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
> struct rcu_node *rnp_old = NULL;
>
> /* Funnel through hierarchy to reduce memory contention. */
> - rnp = per_cpu_ptr(rsp->rda, raw_smp_processor_id())->mynode;
> + rnp = __this_cpu_read(rsp->rda->mynode);
> for (; rnp != NULL; rnp = rnp->parent) {
> ret = (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) ||
> !raw_spin_trylock(&rnp->fqslock);
>
On Fri, Nov 16, 2012 at 04:32:50PM +0800, Shan Wei wrote:
> Shan Wei said, at 2012/11/13 9:52:
> > From: Shan Wei <[email protected]>
> >
> > Signed-off-by: Shan Wei <[email protected]>
> > Acked-by: Christoph Lameter <[email protected]>
>
> Paul, would you like to pick it up to your tree?
Hello, Shan Wei,
If you either show me some significant performance benefits or get me
an independent Tested-by, in both cases on a range of hardware (e.g.,
x86 on the one hand and ARM or Power on the other), then I will queue it.
I wasn't prioritizing this one very high because it does not appear
to be on any sort of fastpath. If I am wrong about that, then you
have a good performance-benefit case, right? ;-)
Thanx, Paul
> > ---
> > no changes vs v3,v2.
> > ---
> > kernel/rcutree.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> > index 74df86b..441b945 100644
> > --- a/kernel/rcutree.c
> > +++ b/kernel/rcutree.c
> > @@ -1960,7 +1960,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
> > struct rcu_node *rnp_old = NULL;
> >
> > /* Funnel through hierarchy to reduce memory contention. */
> > - rnp = per_cpu_ptr(rsp->rda, raw_smp_processor_id())->mynode;
> > + rnp = __this_cpu_read(rsp->rda->mynode);
> > for (; rnp != NULL; rnp = rnp->parent) {
> > ret = (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) ||
> > !raw_spin_trylock(&rnp->fqslock);
> >
>
On Fri, 16 Nov 2012, Paul E. McKenney wrote:
> If you either show me some significant performance benefits or get me
> an independent Tested-by, in both cases on a range of hardware (e.g.,
> x86 on the one hand and ARM or Power on the other), then I will queue it.
Just putting the code generated for x86 before and after side
by side would be enough to convince you I think.
> I wasn't prioritizing this one very high because it does not appear
> to be on any sort of fastpath. If I am wrong about that, then you
> have a good performance-benefit case, right? ;-)
I do not think this needs to be a priority item. Just stick it in the tree
somewhere to merge for the next merge period.
On Fri, Nov 16, 2012 at 05:42:14PM +0000, Christoph Lameter wrote:
>
> On Fri, 16 Nov 2012, Paul E. McKenney wrote:
>
> > If you either show me some significant performance benefits or get me
> > an independent Tested-by, in both cases on a range of hardware (e.g.,
> > x86 on the one hand and ARM or Power on the other), then I will queue it.
>
> Just putting the code generated for x86 before and after side
> by side would be enough to convince you I think.
If accompanied by similar before/after code for ARM or Power, sure.
Thanx, Paul
> > I wasn't prioritizing this one very high because it does not appear
> > to be on any sort of fastpath. If I am wrong about that, then you
> > have a good performance-benefit case, right? ;-)
>
> I do not think this needs to be a priority item. Just stick it in the tree
> somewhere to merge for the next merge period.
>