On 2017/9/6 16:36, Thomas Gleixner write:
Ok. Still that patch has issues.
1) It's white space damaged. Please use TAB not spaces for
indentation. checkpatch.pl would have told you.
2) Why are you using _cond_resched() instead of plain cond_resched().
cond_resched() is what you want to
On Wed, Sep 06, 2017 at 10:56:08AM +0200, Peter Zijlstra wrote:
> Right, but even if it was a coherent patch, I'm not sure it makes sense.
>
> futex_wait() / futex_wake() don't make ordering guarantees and in
> general you don't get to have wakeup preemption if you don't run a
> PREEMPT kernel.
>
On Wed, Sep 06, 2017 at 10:36:29AM +0200, Thomas Gleixner wrote:
> On Wed, 6 Sep 2017, chengjian (D) wrote:
>
> > > > diff --git a/kernel/futex.c b/kernel/futex.c
> > > > index 3d38eaf..0b2d17a 100644
> > > > --- a/kernel/futex.c
> > > > +++ b/kernel/futex.c
> > > > @@ -1545,6 +1545,7 @@ static in
On Wed, 6 Sep 2017, chengjian (D) wrote:
> > > diff --git a/kernel/futex.c b/kernel/futex.c
> > > index 3d38eaf..0b2d17a 100644
> > > --- a/kernel/futex.c
> > > +++ b/kernel/futex.c
> > > @@ -1545,6 +1545,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32
> > > uval,
> > > struct futex_pi_state
diff --git a/kernel/futex.c b/kernel/futex.c
index 3d38eaf..0b2d17a 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1545,6 +1545,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval,
struct futex_pi_state *pi_
spin_unlock(&hb->lock);
wake_up_q(&wake_q);
+_cond_res
On Tue, 5 Sep 2017, chengjian (D) wrote:
> int main(int argc, char** argv)
> {
> pthread_t id1;
> pthread_t id2;
>
> printf("main pid = %d\n", getpid( ));
>
> pthread_mutex_init(&mutex, NULL);
So this is a plain mutex, which maps to a plain futex.
> use perf ftr
A competition happend when some thread use pthread_mutex(futex in
kernel). I make a demo about this : two thread get a lock and then sleep
for a few time, finally unlock when waked up.
```cpp
pthread_mutex_lock(&mutex);
//printf("tid = %lu, count = %d\n", pthread_self( ), i);
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