On Sat, May 04, 2013 at 10:23:31AM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Fri, 3 May 2013, Paul E. McKenney wrote:
>
> > static inline int cond_resched_rcu(void)
> > {
> > #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
> > rcu_read_unlock();
> > co
Hello,
On Fri, 3 May 2013, Paul E. McKenney wrote:
> static inline int cond_resched_rcu(void)
> {
> #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
> rcu_read_unlock();
> cond_resched();
> rcu_read_lock();
> #endif
> }
>
> This adds absolutely no
> This happens in only two cases:
>
> 1.CONFIG_PREEMPT_RCU=n kernels. But in this case, rcu_read_unlock()
> and rcu_read_lock() are free, at least for CONFIG_PROVE_LOCKING=n
> kernels. And if you have CONFIG_PROVE_LOCKING=y, any contribution
> from rcu_read_unlock() and rcu
Hello,
On Fri, 3 May 2013, Paul E. McKenney wrote:
> OK, after getting some sleep, I might have located the root cause of
> my confusion yesterday.
>
> The key point is that I don't understand why we cannot get the effect
> we are looking for with the following in sched.h (or wherever):
On Fri, May 03, 2013 at 07:04:47PM +0200, Peter Zijlstra wrote:
> > The key point is that I don't understand why we cannot get the effect
> > we are looking for with the following in sched.h (or wherever):
> >
> > static inline int cond_resched_rcu(void)
> > {
> > #if defined(CONFIG_DEBUG_ATOMIC_S
> The key point is that I don't understand why we cannot get the effect
> we are looking for with the following in sched.h (or wherever):
>
> static inline int cond_resched_rcu(void)
> {
> #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
> rcu_read_unlock();
> con
On Fri, May 03, 2013 at 10:52:36AM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Thu, 2 May 2013, Paul E. McKenney wrote:
>
> > mainline, and missed the one that you added. Revisiting that, a
> > question:
> >
> > > +#ifdef CONFIG_PREEMPT_RCU
> > > +#define PREEMPT_RCU_OFFSET 1
>
Hello,
On Thu, 2 May 2013, Paul E. McKenney wrote:
> mainline, and missed the one that you added. Revisiting that, a
> question:
>
> > +#ifdef CONFIG_PREEMPT_RCU
> > +#define PREEMPT_RCU_OFFSET 1
>
> Does this really want to be "1" instead of PREEMPT_OFFSET?
In this case
On Thu, May 02, 2013 at 11:19:12PM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Thu, 2 May 2013, Paul E. McKenney wrote:
>
> > > Only the new cond_resched_rcu() macro provides
> > > PREEMPT_ACTIVE flag to skip the rcu_preempt_sleep_check()
> > > call. The old macros provide locked=0
Hello,
On Thu, 2 May 2013, Paul E. McKenney wrote:
> > Only the new cond_resched_rcu() macro provides
> > PREEMPT_ACTIVE flag to skip the rcu_preempt_sleep_check()
> > call. The old macros provide locked=0 as you noticed. Does it
> > answer your question or I'm missing something?
>
On Thu, May 02, 2013 at 09:55:54PM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Thu, 2 May 2013, Paul E. McKenney wrote:
>
> > On Thu, May 02, 2013 at 06:54:05PM +0300, Julian Anastasov wrote:
> > >
> > > I tested the following patch in 2 variants,
> > > TINY_RCU and CONFIG_TREE_PRE
Hello,
On Thu, 2 May 2013, Julian Anastasov wrote:
> Note that I'm testing on some 9-year old
> UP system, i.e. 1 CPU. Now I enabled SMP to test CONFIG_TREE_RCU
> and the results are same. I think, it should be just like
> the TINY_RCU in terms of these debuggings (non-preempt). Ex
Hello,
On Thu, 2 May 2013, Paul E. McKenney wrote:
> On Thu, May 02, 2013 at 06:54:05PM +0300, Julian Anastasov wrote:
> >
> > I tested the following patch in 2 variants,
> > TINY_RCU and CONFIG_TREE_PREEMPT_RCU. I see the
>
> Could you please also try CONFIG_TREE_RCU?
Not
On Thu, May 02, 2013 at 06:54:05PM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Thu, 2 May 2013, Peter Zijlstra wrote:
>
> > On Wed, May 01, 2013 at 09:22:08PM +0300, Julian Anastasov wrote:
> > > > +extern int __cond_resched_rcu(void);
> > > > +
> > > > +#define cond_resched_rcu() ({
Hello,
On Thu, 2 May 2013, Peter Zijlstra wrote:
> On Wed, May 01, 2013 at 09:22:08PM +0300, Julian Anastasov wrote:
> > > +extern int __cond_resched_rcu(void);
> > > +
> > > +#define cond_resched_rcu() ({\
> > > + __might_sleep(__FILE__, __LINE__, 0); \
> >
> >
Hello,
On Thu, 2 May 2013, Peter Zijlstra wrote:
> On Wed, May 01, 2013 at 09:22:08PM +0300, Julian Anastasov wrote:
> > > +extern int __cond_resched_rcu(void);
> > > +
> > > +#define cond_resched_rcu() ({\
> > > + __might_sleep(__FILE__, __LINE__, 0); \
> >
> >
On Wed, May 01, 2013 at 07:32:58AM -0700, Paul E. McKenney wrote:
> Here is how to detect this:
>
> static void inline cond_resched_rcu_lock(void)
> {
> rcu_read_unlock();
> WARN_ON_ONCE(rcu_read_lock_held());
> #ifndef CONFIG_PREEMPT_RCU
>
On Wed, May 01, 2013 at 09:22:08PM +0300, Julian Anastasov wrote:
> > +extern int __cond_resched_rcu(void);
> > +
> > +#define cond_resched_rcu() ({ \
> > + __might_sleep(__FILE__, __LINE__, 0); \
>
> I see your goal. But digging into __might_sleep()
> I see that rcu
On Wed, May 01, 2013 at 09:22:08PM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Wed, 1 May 2013, Peter Zijlstra wrote:
>
> > On Wed, May 01, 2013 at 05:22:05PM +0300, Julian Anastasov wrote:
> >
> > > 2. Same without need_resched because cond_resched already
> > > performs the same ch
Hello,
On Wed, 1 May 2013, Peter Zijlstra wrote:
> On Wed, May 01, 2013 at 05:22:05PM +0300, Julian Anastasov wrote:
>
> > 2. Same without need_resched because cond_resched already
> > performs the same checks:
> >
> > static void inline cond_resched_rcu_lock(void)
> > {
> > #ifndef CO
On Wed, May 01, 2013 at 06:57:49PM +0200, Peter Zijlstra wrote:
> On Wed, May 01, 2013 at 09:02:18AM -0700, Paul E. McKenney wrote:
> > My guess would be for the case where sched_preempt_enable_no_resched()
> > is followed some time later by cond_resched().
>
> I might hope not.. preempt_enable_no
On Wed, May 01, 2013 at 09:02:18AM -0700, Paul E. McKenney wrote:
> My guess would be for the case where sched_preempt_enable_no_resched()
> is followed some time later by cond_resched().
I might hope not.. preempt_enable_no_resched() is nasty and you're likely to be
hit with a frozen fish of sort
On Wed, May 01, 2013 at 08:29:55AM -0700, Eric Dumazet wrote:
> On Wed, 2013-05-01 at 17:17 +0200, Peter Zijlstra wrote:
> > On Wed, May 01, 2013 at 05:46:37AM -0700, Paul E. McKenney wrote:
> >
> > > If the only goal is to allow preemption, and if long grace periods are
> > > not a concern, then
On Wed, May 01, 2013 at 08:29:55AM -0700, Eric Dumazet wrote:
> On Wed, 2013-05-01 at 17:17 +0200, Peter Zijlstra wrote:
> > On Wed, May 01, 2013 at 05:46:37AM -0700, Paul E. McKenney wrote:
> >
> > > If the only goal is to allow preemption, and if long grace periods are
> > > not a concern, then
On Wed, May 01, 2013 at 05:22:05PM +0300, Julian Anastasov wrote:
> > static void inline cond_resched_rcu_lock(void)
> > {
> > #ifdef CONFIG_PREEMPT_RCU
>
> You mean '#ifndef' here, right? But in the non-preempt
> case is using the need_resched() needed? rcu_read_unlock
> and rcu_read_lock
On Wed, 2013-05-01 at 17:17 +0200, Peter Zijlstra wrote:
> On Wed, May 01, 2013 at 05:46:37AM -0700, Paul E. McKenney wrote:
>
> > If the only goal is to allow preemption, and if long grace periods are
> > not a concern, then this alternate approach would work fine as well.
>
> Hmm.. if that were
On Wed, May 01, 2013 at 05:46:37AM -0700, Paul E. McKenney wrote:
> If the only goal is to allow preemption, and if long grace periods are
> not a concern, then this alternate approach would work fine as well.
Hmm.. if that were the goal I'd like it to have a different name;
cond_resched*() has a
On Wed, May 01, 2013 at 05:46:37AM -0700, Paul E. McKenney wrote:
> On Wed, May 01, 2013 at 11:10:12AM +0200, Peter Zijlstra wrote:
> > On Tue, Apr 30, 2013 at 10:52:38AM +0300, Julian Anastasov wrote:
> > >
> > > Hello,
> > >
> > > On Tue, 30 Apr 2013, Simon Horman wrote:
> > >
> > > > > > +s
Hello,
On Wed, 1 May 2013, Peter Zijlstra wrote:
> On Tue, Apr 30, 2013 at 10:52:38AM +0300, Julian Anastasov wrote:
> >
> > Hello,
> >
> > On Tue, 30 Apr 2013, Simon Horman wrote:
> >
> > > Thanks, to clarify, just this:
> > >
> > > static void inline cond_resched_rcu_lock(void)
On Wed, May 01, 2013 at 11:10:12AM +0200, Peter Zijlstra wrote:
> On Tue, Apr 30, 2013 at 10:52:38AM +0300, Julian Anastasov wrote:
> >
> > Hello,
> >
> > On Tue, 30 Apr 2013, Simon Horman wrote:
> >
> > > > > +static void inline cond_resched_rcu_lock(void)
> > > > > +{
> > > > > + if (n
On Tue, Apr 30, 2013 at 10:52:38AM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Tue, 30 Apr 2013, Simon Horman wrote:
>
> > > > +static void inline cond_resched_rcu_lock(void)
> > > > +{
> > > > + if (need_resched()) {
> > >
> > > Ops, it should be without above need_resched.
Hello,
On Tue, 30 Apr 2013, Simon Horman wrote:
> > > +static void inline cond_resched_rcu_lock(void)
> > > +{
> > > + if (need_resched()) {
> >
> > Ops, it should be without above need_resched.
>
> Thanks, to clarify, just this:
>
> static void inline cond_resched_rcu_lock(void)
On Tue, Apr 30, 2013 at 10:12:38AM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Tue, 30 Apr 2013, Simon Horman wrote:
>
> > This is intended for use in loops which read data protected by RCU and may
> > have a large number of iterations. Such an example is dumping the list of
> > conn
Hello,
On Tue, 30 Apr 2013, Simon Horman wrote:
> This is intended for use in loops which read data protected by RCU and may
> have a large number of iterations. Such an example is dumping the list of
> connections known to IPVS: ip_vs_conn_array() and ip_vs_conn_seq_next().
>
> The ca
This is intended for use in loops which read data protected by RCU and may
have a large number of iterations. Such an example is dumping the list of
connections known to IPVS: ip_vs_conn_array() and ip_vs_conn_seq_next().
The call to cond_resched() is guarded by #ifndef CONFIG_PREEMPT_RCU as in
t
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