On Mon, 2014-02-03 at 20:25 +0100, Peter Zijlstra wrote:
> +void m_spin_unlock(struct m_spinlock **lock)
> +{
> + struct m_spinlock *node = this_cpu_ptr(&m_node);
> + struct m_spinlock *next;
> +
> + if (likely(cmpxchg(lock, node, NULL) == node))
> + return;
At this curren
On Wed, 2014-02-05 at 16:44 -0500, Waiman Long wrote:
> On 01/29/2014 06:51 AM, Peter Zijlstra wrote:
> > On Tue, Jan 28, 2014 at 02:51:35PM -0800, Jason Low wrote:
> >>> But urgh, nasty problem. Lemme ponder this a bit.
> > OK, please have a very careful look at th
und that it was able to
reduce the overhead of the function by up to a factor of 20x.
Cc: Yuyang Du
Cc: Waiman Long
Cc: Mel Gorman
Cc: Mike Galbraith
Cc: Rik van Riel
Cc: Aswin Chandramouleeswaran
Cc: Chegu Vinod
Cc: Scott J Norton
Signed-off-by: Jason Low
---
kernel/sched/fair.c | 10
On Tue, 2014-08-26 at 16:24 -0700, Paul Turner wrote:
> On Tue, Aug 26, 2014 at 4:11 PM, Jason Low wrote:
> > Based on perf profiles, the update_cfs_rq_blocked_load function constantly
> > shows up as taking up a noticeable % of system run time. This is especially
> > ap
On Wed, 2014-08-27 at 16:32 -0700, Tim Chen wrote:
> On Wed, 2014-08-27 at 10:34 -0700, Jason Low wrote:
> > On Tue, 2014-08-26 at 16:24 -0700, Paul Turner wrote:
> > > On Tue, Aug 26, 2014 at 4:11 PM, Jason Low wrote:
> > > > Based on perf profiles, the updat
reduces the
cacheline contention that would be unnecessary.
Cc: Yuyang Du
Cc: Aswin Chandramouleeswaran
Cc: Chegu Vinod
Cc: Scott J Norton
Reviewed-by: Ben Segall
Reviewed-by: Waiman Long
Signed-off-by: Jason Low
---
kernel/sched/fair.c |3 +++
1 files changed, 3 insertions(+), 0 delet
On Tue, 2014-08-05 at 03:15 +0800, Yuyang Du wrote:
> Hi Jason,
>
> I am not sure whether you noticed my latest work: rewriting per entity load
> average
>
> http://article.gmane.org/gmane.linux.kernel/1760754
> http://article.gmane.org/gmane.linux.kernel/1760755
> http://article.gmane.org/gmane
On Tue, 2014-08-05 at 03:15 +0800, Yuyang Du wrote:
> Hi Jason,
>
> I am not sure whether you noticed my latest work: rewriting per entity load
> average
>
> http://article.gmane.org/gmane.linux.kernel/1760754
> http://article.gmane.org/gmane.linux.kernel/1760755
> http://article.gmane.org/gmane
On Fri, 2014-08-08 at 02:02 +0800, Yuyang Du wrote:
> On Wed, Aug 06, 2014 at 11:21:35AM -0700, Jason Low wrote:
> > I ran these tests with most of the AIM7 workloads to compare its
> > performance between a 3.16 kernel and the kernel with these patches
> > applied.
>
> __visible __used noinline
> @@ -730,6 +744,23 @@ __mutex_unlock_common_slowpath(struct mutex *lock, int
> nested)
> if (__mutex_slowpath_needs_to_unlock())
> atomic_set(&lock->count, 1);
>
> +/*
> + * Skipping the mutex_has_owner() check when DEBUG, allows us to
> + * avo
On Fri, 2014-08-08 at 13:21 -0700, Davidlohr Bueso wrote:
> On Fri, 2014-08-08 at 12:50 -0700, Jason Low wrote:
> > > __visible __used noinline
> > > @@ -730,6 +744,23 @@ __mutex_unlock_common_slowpath(struct mutex *lock,
> > > int nested)
> > >
On Mon, 2014-08-04 at 13:52 -0700, bseg...@google.com wrote:
>
> That said, it might be better to remove force_update for this function,
> or make it just reduce the minimum to /64 or something. If the test is
> easy to run it would be good to see what it's like just removing the
> force_update pa
On Sun, 2014-08-03 at 22:36 -0400, Waiman Long wrote:
> The rwsem_can_spin_on_owner() function currently allows optimistic
> spinning only if the owner field is defined and is running. That is
> too conservative as it will cause some tasks to miss the opportunity
> of doing spinning in case the own
a factor of 3x:
1.18%reaim [kernel.kallsyms][k] update_cfs_rq_blocked_load
Signed-off-by: Jason Low
---
kernel/sched/fair.c |3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index bfa3c86..8d4cc72 100644
---
On Mon, 2014-08-04 at 22:48 +0200, Peter Zijlstra wrote:
> On Mon, Aug 04, 2014 at 02:36:35PM -0400, Waiman Long wrote:
> > On 08/04/2014 03:55 AM, Peter Zijlstra wrote:
> > >On Sun, Aug 03, 2014 at 10:36:16PM -0400, Waiman Long wrote:
> > >>For a fully preemptive kernel, a call to preempt_enable()
On Sun, 2014-08-03 at 22:36 -0400, Waiman Long wrote:
> On a highly contended rwsem, spinlock contention due to the slow
> rwsem_wake() call can be a significant portion of the total CPU cycles
> used. With writer lock stealing and writer optimistic spinning, there
> is also a pretty good chance th
On Mon, 2014-08-04 at 13:52 -0700, bseg...@google.com wrote:
> Jason Low writes:
>
> > When running workloads on 2+ socket systems, based on perf profiles, the
> > update_cfs_rq_blocked_load function constantly shows up as taking up a
> > noticeable % of run time. This i
ore than 30%.
This patch addresses this by having the thread_group_cputimer structure
maintain a boolean to signify when a thread in the group is already
checking for process wide timers, and adds extra logic in the fastpath
to check the boolean.
Signed-off-by: Jason Low
---
include/linux/init_task.h
On Wed, 2015-08-05 at 11:37 +0200, Peter Zijlstra wrote:
> On Tue, Aug 04, 2015 at 05:29:44PM -0700, Jason Low wrote:
>
> > @@ -1137,6 +1148,13 @@ static inline int fastpath_timer_check(struct
> > task_struct *tsk)
> > if (READ_ONCE(sig->cputimer.runni
there are no per-thread timers.
Signed-off-by: Jason Low
---
kernel/time/posix-cpu-timers.c | 10 ++
1 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 02596ff..535bef5 100644
--- a/kernel/time/posix-cpu
timers set.
Signed-off-by: Jason Low
---
kernel/time/posix-cpu-timers.c | 15 +++
1 files changed, 7 insertions(+), 8 deletions(-)
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 892e3da..02596ff 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b
time is spent
trying to acquire the sighand lock. It was found in some cases that
200+ threads were simultaneously contending for the same sighand lock,
reducing throughput by more than 30%.
Jason Low (3):
timer: Optimize fastpath_timer_check()
timer: Check thread timers only when there are
tain a boolean to signify when a thread in the group is already
checking for process wide timers, and adds extra logic in the fastpath
to check the boolean.
Signed-off-by: Jason Low
---
include/linux/init_task.h |1 +
include/linux/sched.h |3 +++
kernel/time/
Hi Andrew,
On Tue, 2015-08-25 at 20:27 -0700, Andrew Morton wrote:
> On Tue, 25 Aug 2015 20:17:45 -0700 Jason Low wrote:
>
> > When running a database workload on a 16 socket machine, there were
> > scalability issues related to itimers.
> >
> > Commit 1018016c706
On Wed, 2015-08-26 at 12:57 -0400, George Spelvin wrote:
> > if (!task_cputime_zero(&tsk->cputime_expires)) {
> >+struct task_cputime task_sample;
> >+cputime_t utime, stime;
> >+
> >+task_cputime(tsk, &utime, &stime);
> >+task_sample.utime = utim
On Wed, 2015-08-26 at 13:04 -0400, George Spelvin wrote:
> - check_thread_timers(tsk, &firing);
> + if (!task_cputime_zero(&tsk->cputime_expires))
> + check_thread_timers(tsk, &firing);
>
> Sincere question; I'm not certain myself: would it make more sense to put
> this shortcu
On Wed, 2015-08-26 at 19:08 +0200, Oleg Nesterov wrote:
> On 08/26, Jason Low wrote:
> >
> > Hi Andrew,
> >
> > On Tue, 2015-08-25 at 20:27 -0700, Andrew Morton wrote:
> > > On Tue, 25 Aug 2015 20:17:45 -0700 Jason Low wrote:
> > >
> > > >
On Thu, 2015-08-27 at 00:31 +0200, Frederic Weisbecker wrote:
> On Wed, Aug 26, 2015 at 10:53:35AM -0700, Linus Torvalds wrote:
> > On Tue, Aug 25, 2015 at 8:17 PM, Jason Low wrote:
> > >
> > > This patch addresses this by having the thread_group_cputimer structure
On Thu, 2015-08-27 at 00:56 +0200, Frederic Weisbecker wrote:
> On Tue, Aug 25, 2015 at 08:17:48PM -0700, Jason Low wrote:
> > It was found while running a database workload on large systems that
> > significant time was spent trying to acquire the sighand lock.
> >
&
On Wed, 2015-08-26 at 15:33 -0400, George Spelvin wrote:
> And some more comments on the series...
>
> > @@ -626,6 +628,7 @@ struct task_cputime_atomic {
> > struct thread_group_cputimer {
> > struct task_cputime_atomic cputime_atomic;
> > int running;
> >+int checking_timer;
> > };
>
On Wed, 2015-08-26 at 16:32 -0700, Jason Low wrote:
> Perhaps to be safer, we use something like load_acquire() and
> store_release() for accessing both the ->running and ->checking_timer
> fields?
Regarding using barriers, one option could be to pair them between
sig->cputi
> >
> > nohz_idle_balance must set the nohz.next_balance without taking into
> > account this_rq->next_balance which is not updated yet. Then, this_rq will
> > update nohz.next_update with its next_balance once updated and if necessary.
> >
> > Signed-off-by:
On Thu, 2015-08-27 at 14:53 +0200, Frederic Weisbecker wrote:
> On Wed, Aug 26, 2015 at 04:32:34PM -0700, Jason Low wrote:
> > On Thu, 2015-08-27 at 00:56 +0200, Frederic Weisbecker wrote:
> > > On Tue, Aug 25, 2015 at 08:17:48PM -0700, Jason Low wrote:
> > > >
On Wed, 2015-08-26 at 21:28 -0400, George Spelvin wrote:
> > I can include your patch in the series and then use boolean for the new
> > checking_timer field. However, it looks like this applies on an old
> > kernel. For example, the spin_lock field has already been removed from
> > the structure.
On Thu, 2015-08-06 at 16:18 +0200, Oleg Nesterov wrote:
> On 08/04, Jason Low wrote:
> >
> > @@ -973,13 +981,6 @@ static void check_process_timers(struct task_struct
> > *tsk,
> > virt_expires = check_timers_list(++timers, firing, utime);
> > sched_exp
On Wed, 2016-04-13 at 10:43 -0700, Will Deacon wrote:
> On Tue, Apr 12, 2016 at 08:02:17PM -0700, Jason Low wrote:
> > For qspinlocks on ARM64, we would like to use WFE instead
> > of purely spinning. Qspinlocks internally have lock
> > contenders spin on an MCS
Use WFE to avoid most spinning with MCS spinlocks. This is implemented
with the new cmpwait() mechanism for comparing and waiting for the MCS
locked value to change using LDXR + WFE.
Signed-off-by: Jason Low
---
arch/arm64/include/asm/mcs_spinlock.h | 21 +
1 file changed
>
>19.95% 5.88% fio [kernel.vmlinux] [k] rwsem_down_write_failed
>14.20% 1.52% fio [kernel.vmlinux] [k] rwsem_down_write_failed
>
> The actual CPU cycles spend in rwsem_down_write_failed() dropped from
> 5.88% to 1.52% after the patch.
>
> The xfstests was also run and no regression was observed.
>
> Signed-off-by: Waiman Long
Acked-by: Jason Low
operations.
We can instead make the list_is_singular() check first, and then
set the count accordingly, so that we issue at most 1 atomic
operation when acquiring the write lock and reduce unnecessary
cacheline contention.
Signed-off-by: Jason Low
---
kernel/locking/rwsem-xadd.c | 20
On Wed, 2016-05-04 at 13:27 -0400, Waiman Long wrote:
> On 05/03/2016 08:21 PM, Davidlohr Bueso wrote:
> > On Wed, 27 Apr 2016, Waiman Long wrote:
> >> static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
> >> @@ -378,7 +367,8 @@ static bool rwsem_optimistic_spin(struct
> >> rw_semaphore *s
On Wed, 2016-05-11 at 13:49 +0200, Peter Zijlstra wrote:
> On Mon, May 09, 2016 at 12:16:37PM -0700, Jason Low wrote:
> > When acquiring the rwsem write lock in the slowpath, we first try
> > to set count to RWSEM_WAITING_BIAS. When that is successful,
> > we th
On Wed, 2016-05-11 at 11:33 -0700, Davidlohr Bueso wrote:
> On Wed, 11 May 2016, Peter Zijlstra wrote:
>
> >On Mon, May 09, 2016 at 12:16:37PM -0700, Jason Low wrote:
> >> When acquiring the rwsem write lock in the slowpath, we first try
> >> to set count to RW
On Fri, 2016-05-20 at 16:27 -0400, Waiman Long wrote:
> On 05/19/2016 06:23 PM, Jason Low wrote:
> > The mutex owner can get read and written to without the wait_lock.
> > Use WRITE_ONCE when setting and clearing the owner field in order
> > to avoid optimizations such a
use a partially written owner value.
Signed-off-by: Jason Low
Acked-by: Davidlohr Bueso
---
kernel/locking/mutex-debug.h | 4 ++--
kernel/locking/mutex.h | 10 --
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/kernel/locking/mutex-debug.h b/kernel/locking/mutex
On Sat, 2016-05-21 at 09:04 -0700, Peter Hurley wrote:
> On 05/18/2016 12:58 PM, Jason Low wrote:
> > It should be fine to use the standard READ_ONCE here, even if it's just
> > for documentation, as it's probably not going to cost anything in
> > practice. It woul
On Fri, 2016-05-20 at 18:00 -0700, Davidlohr Bueso wrote:
> On Fri, 20 May 2016, Waiman Long wrote:
>
> >I think mutex-debug.h also needs similar changes for completeness.
>
> Maybe, but given that with debug the wait_lock is unavoidable, doesn't
> this send the wrong message?
The mutex_set_owne
On Mon, 2016-05-23 at 14:31 -0700, Davidlohr Bueso wrote:
> On Mon, 23 May 2016, Jason Low wrote:
>
> >On Fri, 2016-05-20 at 18:00 -0700, Davidlohr Bueso wrote:
> >> On Fri, 20 May 2016, Waiman Long wrote:
> >>
> >> >I think mutex-debug.h a
use a partially written owner value.
This is not necessary in the debug case where the owner gets
modified with the wait_lock held.
Signed-off-by: Jason Low
Acked-by: Davidlohr Bueso
Acked-by: Waiman Long
---
kernel/locking/mutex-debug.h | 5 +
kernel/locking/mutex.h | 10
On Tue, 2016-05-17 at 13:09 +0200, Peter Zijlstra wrote:
> On Mon, May 16, 2016 at 06:12:25PM -0700, Linus Torvalds wrote:
> > On Mon, May 16, 2016 at 5:37 PM, Jason Low wrote:
> > >
> > > This rest of the series converts the rwsem count variable to an
> > >
On Wed, 2016-05-18 at 07:04 -0700, Davidlohr Bueso wrote:
> On Tue, 17 May 2016, Waiman Long wrote:
>
> >Without using WRITE_ONCE(), the compiler can potentially break a
> >write into multiple smaller ones (store tearing). So a read from the
> >same data by another task concurrently may return a p
D_ONCE() may
> >not be needed for rwsem->owner as long as the value is only used for
> >comparison and not dereferencing.
> >
> >Signed-off-by: Waiman Long
>
> Yes, ->owner can obviously be handled locklessly during optimistic
> spinning.
>
> Acked-by: Davidlohr Bueso
Acked-by: Jason Low
On Wed, 2016-05-18 at 14:29 -0400, Waiman Long wrote:
> On 05/18/2016 01:21 PM, Jason Low wrote:
> > On Wed, 2016-05-18 at 07:04 -0700, Davidlohr Bueso wrote:
> >> On Tue, 17 May 2016, Waiman Long wrote:
> >>
> >>> Without using WRITE_ONCE(), the compiler c
On Wed, 2016-05-18 at 12:58 -0700, Jason Low wrote:
> On Wed, 2016-05-18 at 14:29 -0400, Waiman Long wrote:
> > On 05/18/2016 01:21 PM, Jason Low wrote:
> > > On Wed, 2016-05-18 at 07:04 -0700, Davidlohr Bueso wrote:
> > >> On Tue, 17 May 2016, Waiman Long wrote
read and use a
partially written owner value.
Signed-off-by: Jason Low
---
kernel/locking/mutex.h | 10 --
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/kernel/locking/mutex.h b/kernel/locking/mutex.h
index 5cda397..469b61e 100644
--- a/kernel/locking/mutex.h
+++ b/kernel
operations.
We can instead make the list_is_singular() check first, and then
set the count accordingly, so that we issue at most 1 atomic
operation when acquiring the write lock and reduce unnecessary
cacheline contention.
Signed-off-by: Jason Low
Acked-by: Waiman Long
Acked-by: Davidlohr Bueso
The first patch contains an optimization for acquiring the rwsem write lock
in the slowpath.
This rest of the series converts the rwsem count variable to an atomic_long_t
since it is used it as an atomic variable. This allows us to also remove
the rwsem_atomic_{add,update} abstraction and reduce 1
add,update} definitions across the various architectures.
Suggested-by: Peter Zijlstra
Signed-off-by: Jason Low
---
include/linux/rwsem.h | 6 +++---
kernel/locking/rwsem-xadd.c | 31 ---
2 files changed, 19 insertions(+), 18 deletions(-)
diff --git a/include/linux
operations.
We can instead make the list_is_singular() check first, and then
set the count accordingly, so that we issue at most 1 atomic
operation when acquiring the write lock and reduce unnecessary
cacheline contention.
Signed-off-by: Jason Low
Acked-by: Waiman Long
Acked-by: Davidlohr Bueso
The rwsem count has been converted to an atomic variable and the rwsem
code now directly uses atomic_long_add() and atomic_long_add_return(),
so we can remove the x86 implementation of rwsem_atomic_add() and
rwsem_atomic_update().
Signed-off-by: Jason Low
---
arch/x86/include/asm/rwsem.h | 18
The rwsem count has been converted to an atomic variable and the rwsem
code now directly uses atomic_long_add() and atomic_long_add_return(),
so we can remove the alpha implementation of rwsem_atomic_add() and
rwsem_atomic_update().
Signed-off-by: Jason Low
---
arch/alpha/include/asm/rwsem.h
The rwsem count has been converted to an atomic variable and the rwsem
code now directly uses atomic_long_add() and atomic_long_add_return(),
so we can remove the ia64 implementation of rwsem_atomic_add() and
rwsem_atomic_update().
Signed-off-by: Jason Low
---
arch/ia64/include/asm/rwsem.h | 7
The rwsem count has been converted to an atomic variable and the rwsem
code now directly uses atomic_long_add() and atomic_long_add_return(),
so we can remove the s390 implementation of rwsem_atomic_add() and
rwsem_atomic_update().
Signed-off-by: Jason Low
---
arch/s390/include/asm/rwsem.h | 37
The rwsem count has been converted to an atomic variable and we
now directly use atomic_long_add() and atomic_long_add_return()
on the count, so we can remove the asm-generic implementation of
rwsem_atomic_add() and rwsem_atomic_update().
Signed-off-by: Jason Low
---
include/asm-generic/rwsem.h
On Fri, 2016-01-22 at 09:54 +0100, Peter Zijlstra wrote:
> On Thu, Jan 21, 2016 at 06:02:34PM -0500, Waiman Long wrote:
> > This patch attempts to fix this live-lock condition by enabling the
> > a woken task in the wait list to enter optimistic spinning loop itself
> > with precedence over the one
7;s patch:
>
> 1) Ding Tianhong still find that hanging task could happen in some cases.
> 2) Jason Low found that there was performance regression for some AIM7
> workloads.
This might help address the hang that Ding reported.
Performance wise, this patchset reduced AI
On Fri, 2016-02-12 at 14:14 -0800, Davidlohr Bueso wrote:
> On Fri, 12 Feb 2016, Peter Zijlstra wrote:
>
> >On Fri, Feb 12, 2016 at 12:32:12PM -0500, Waiman Long wrote:
> >> static bool mutex_optimistic_spin(struct mutex *lock,
> >> +struct ww_acquire_ctx *ww_ctx,
> >>
On Mon, 2016-02-15 at 18:15 -0800, Jason Low wrote:
> On Fri, 2016-02-12 at 14:14 -0800, Davidlohr Bueso wrote:
> > On Fri, 12 Feb 2016, Peter Zijlstra wrote:
> >
> > >On Fri, Feb 12, 2016 at 12:32:12PM -0500, Waiman Long wrote:
> > >> static bool mute
On Mon, 2016-02-15 at 18:55 -0500, Waiman Long wrote:
> On 02/12/2016 03:40 PM, Peter Zijlstra wrote:
> > On Fri, Feb 12, 2016 at 12:32:12PM -0500, Waiman Long wrote:
> >> @@ -358,8 +373,8 @@ static bool mutex_optimistic_spin(struct mutex *lock,
> >>}
> >>
> >>
On Fri, 2015-05-08 at 06:22 -0700, tip-bot for Jason Low wrote:
> Commit-ID: 1018016c706f7ff9f56fde3a649789c47085a293
> Gitweb: http://git.kernel.org/tip/1018016c706f7ff9f56fde3a649789c47085a293
> Author: Jason Low
> AuthorDate: Tue, 28 Apr 2015 13:00:22 -0700
> Committe
On Fri, 2015-05-01 at 08:21 -0700, Paul E. McKenney wrote:
> On Thu, Apr 30, 2015 at 02:13:07PM -0700, Jason Low wrote:
> > On Thu, 2015-04-30 at 14:42 -0400, Waiman Long wrote:
> >
> > > I do have a question of what kind of tearing you are talking about. Do
> > &g
On Sat, 2015-03-07 at 10:21 +0100, Peter Zijlstra wrote:
> On Fri, Mar 06, 2015 at 11:45:31PM -0800, Jason Low wrote:
> > static noinline
> > bool rwsem_spin_on_owner(struct rw_semaphore *sem, struct task_struct
> > *owner)
> > {
> > long count;
> >
On Sat, 2015-03-07 at 13:17 -0500, Sasha Levin wrote:
> On 03/07/2015 02:45 AM, Jason Low wrote:
> > Fixes tip commit b3fd4f03ca0b (locking/rwsem: Avoid deceiving lock
> > spinners).
> >
> > Ming reported soft lockups occurring when running xfstest due to
> > c
oop
directly check for while (lock->owner == owner). This improves the
readability of the code.
Signed-off-by: Jason Low
---
kernel/locking/mutex.c | 17 +
1 files changed, 5 insertions(+), 12 deletions(-)
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 1
On Tue, 2015-03-10 at 09:11 +0100, Ingo Molnar wrote:
> * Jason Low wrote:
>
> > This patch applies on top of tip.
> >
> > ---
> > Similar to what Linus suggested for rwsem_spin_on_owner(), in
> &g
s a chance to load balance. Else we may
> + * load balance only within the local sched_domain hierarchy
> + * and abort nohz_idle_balance altogether if we pull some load.
>*/
> nohz_idle_balance(this_rq, idle);
> + rebalance_domains(this_rq, idle);
Reviewe
On Fri, 2015-03-27 at 10:03 +0530, Preeti U Murthy wrote:
> Hi Wanpeng
>
> On 03/27/2015 07:42 AM, Wanpeng Li wrote:
> > Hi Preeti,
> > On Thu, Mar 26, 2015 at 06:32:44PM +0530, Preeti U Murthy wrote:
> >>
> >> 1. An ILB CPU was chosen from the first numa domain to trigger nohz idle
> >> load bala
On Fri, 2015-03-27 at 10:12 +0800, Wanpeng Li wrote:
> Hi Preeti,
> On Thu, Mar 26, 2015 at 06:32:44PM +0530, Preeti U Murthy wrote:
> >
> >1. An ILB CPU was chosen from the first numa domain to trigger nohz idle
> >load balancing [Given the experiment, upto 6 CPUs per core could be
> >potentially
need_resched())
> goto end;
How about having:
if (idle != CPU_IDLE || need_resched() ||
!test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
which wouldn't require adding a new line.
Besides that:
Reviewed-by: Jason Low
--
To unsubscribe from this list: se
using separate/multiple sets of APIs.
Signed-off-by: Jason Low
---
mm/gup.c |4 ++--
mm/huge_memory.c |4 ++--
mm/internal.h|4 ++--
mm/ksm.c | 10 +-
mm/memcontrol.c | 18 +-
mm/memory.c |2 +-
mm/mmap.c|8 ---
On Tue, 2015-03-24 at 15:42 +0100, Christian Borntraeger wrote:
> Am 23.03.2015 um 23:44 schrieb Jason Low:
> > Commit 38c5ce936a08 converted ACCESS_ONCE usage in gup_pmd_range() to
> > READ_ONCE, since ACCESS_ONCE doesn't work reliably on non-scalar types.
> >
> >
On Tue, 2015-03-24 at 11:30 +0100, Michal Hocko wrote:
> On Mon 23-03-15 15:44:40, Jason Low wrote:
> > Commit 38c5ce936a08 converted ACCESS_ONCE usage in gup_pmd_range() to
> > READ_ONCE, since ACCESS_ONCE doesn't work reliably on non-scalar types.
> >
> > Th
es_fast() in mm/gup.c
Signed-off-by: Jason Low
Acked-by: Michal Hocko
Acked-by: Davidlohr Bueso
Acked-by: Rik van Riel
Reviewed-by: Christian Borntraeger
---
mm/gup.c |4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index ca7b607..6297f6b 100644
--- a
arate/multiple sets of APIs.
Signed-off-by: Jason Low
Acked-by: Michal Hocko
Acked-by: Davidlohr Bueso
Acked-by: Rik van Riel
Reviewed-by: Christian Borntraeger
---
mm/huge_memory.c |4 ++--
mm/internal.h|4 ++--
mm/ksm.c | 10 +-
mm/memcontrol.c |
v1->v2:
As suggested by Michal, we can split up the v1 patch into 2 patches.
The first patch addresses potentially incorrect usages of ACCESS_ONCE().
The second patch is more of a "cleanup" patch to convert the rest of
the ACCESS_ONCE() reads in mm/ to use the new READ_ONCE() API.
This makes
On Thu, 2015-03-05 at 16:20 +0100, Frederic Weisbecker wrote:
> On Mon, Mar 02, 2015 at 01:44:04PM -0800, Linus Torvalds wrote:
> > On Mon, Mar 2, 2015 at 1:16 PM, Jason Low wrote:
> > >
> > > In original code, we set cputimer->running first so it is running while
&
On Thu, 2015-03-05 at 16:35 +0100, Frederic Weisbecker wrote:
> On Mon, Mar 02, 2015 at 10:42:11AM -0800, Jason Low wrote:
> > +/* Sample thread_group_cputimer values in "cputimer", copy results to
> > "times" */
> > +static inline void sample_
On Fri, 2015-03-06 at 09:19 -0800, Davidlohr Bueso wrote:
> On Fri, 2015-03-06 at 13:32 +0100, Ingo Molnar wrote:
> > * Sasha Levin wrote:
> >
> > > I've bisected this to "locking/rwsem: Check for active lock before
> > > bailing on spinning". Relevant parties Cc'ed.
> >
> > That would be:
> >
On Fri, 2015-03-06 at 11:05 -0800, Linus Torvalds wrote:
> On Fri, Mar 6, 2015 at 10:57 AM, Jason Low wrote:
> >
> > Right, the can_spin_on_owner() was originally added to the mutex
> > spinning code for optimization purposes, particularly so that we can
> > avoid ad
On Fri, 2015-03-06 at 11:29 -0800, Jason Low wrote:
> Hi Linus,
>
> Agreed, this is an issue we need to address, though we're just trying to
> figure out if the change to rwsem_can_spin_on_owner() in "commit:
> 37e9562453b" is really the one that's causing th
On Fri, 2015-03-06 at 13:24 -0800, Linus Torvalds wrote:
> On Fri, Mar 6, 2015 at 1:12 PM, Jason Low wrote:
> >
> > + while (true) {
> > + if (sem->owner != owner)
> > + break;
>
> That looks *really* odd.
>
&g
On Fri, 2015-03-06 at 14:15 -0800, Davidlohr Bueso wrote:
> On Fri, 2015-03-06 at 13:12 -0800, Jason Low wrote:
> > In owner_running() there are 2 conditions that would make it return
> > false: if the owner changed or if the owner is not running. However,
> > that patch
On Sat, 2015-03-07 at 10:10 +0800, Ming Lei wrote:
> On Sat, Mar 7, 2015 at 10:07 AM, Davidlohr Bueso wrote:
> > On Sat, 2015-03-07 at 09:55 +0800, Ming Lei wrote:
> >> On Fri, 06 Mar 2015 14:15:37 -0800
> >> Davidlohr Bueso wrote:
> >>
> >> > On
On Sat, 2015-03-07 at 11:08 +0800, Ming Lei wrote:
> On Sat, Mar 7, 2015 at 10:56 AM, Jason Low wrote:
> > On Sat, 2015-03-07 at 10:10 +0800, Ming Lei wrote:
> >> On Sat, Mar 7, 2015 at 10:07 AM, Davidlohr Bueso wrote:
> >> > On Sat, 2015-03-07 at 09:55 +0800, Ming
On Sat, 2015-03-07 at 11:39 +0800, Ming Lei wrote:
> On Sat, Mar 7, 2015 at 11:17 AM, Jason Low wrote:
> > On Sat, 2015-03-07 at 11:08 +0800, Ming Lei wrote:
> >> On Sat, Mar 7, 2015 at 10:56 AM, Jason Low wrote:
> >> > On Sat, 2015-03-07 at 10:10 +0800, Ming Le
On Fri, 2015-03-06 at 13:12 -0800, Jason Low wrote:
Just in case, here's the updated patch which addresses Linus's comments
and with a changelog.
Note: The changelog says that it fixes (locking/rwsem: Avoid deceiving
lock spinners), though I still haven't seen full confirmation th
On Fri, 2015-03-06 at 20:44 -0800, Davidlohr Bueso wrote:
> On Fri, 2015-03-06 at 20:31 -0800, Jason Low wrote:
> > On Fri, 2015-03-06 at 13:12 -0800, Jason Low wrote:
> >
> > Just in case, here's the updated patch which addresses Linus's comments
> > and
On Sat, 2015-03-07 at 13:54 +0800, Ming Lei wrote:
> On Sat, Mar 7, 2015 at 12:31 PM, Jason Low wrote:
> > On Fri, 2015-03-06 at 13:12 -0800, Jason Low wrote:
> > Cc: Ming Lei
> > Cc: Davidlohr Bueso
> > Signed-off-by: Jason Low
>
> Reported-and-tested-by
ot;guess" why we broke out of the loop to make
this more readable.
Reported-and-tested-by: Ming Lei
Acked-by: Davidlohr Bueso
Signed-off-by: Jason Low
---
kernel/locking/rwsem-xadd.c | 31 +++
1 files changed, 11 insertions(+), 20 deletions(-)
diff --git a/kernel
This patchset contains a few modifications to mutex_spin_on_owner().
The first patch makes the optimistic spinner continue spinning whenever
the owner changes, and the second patch refactors mutex_spin_on_owner()
to micro optimize the code as well as make it simpler.
Jason Low (2):
mutex: In
with
this patch.
Signed-off-by: Jason Low
---
kernel/locking/mutex.c |8
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 4541951..04ea9ce 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -237,1
301 - 400 of 490 matches
Mail list logo
