On 9/4/19 1:39 PM, Steven Rostedt wrote:
On Tue, 3 Sep 2019 15:25:59 +0200
Viktor Rosendahl wrote:
+void latency_fsnotify_stop(void)
+{
+ /* Make sure all CPUs see caller's previous actions to stop tracer */
+ smp_wmb();
These memory barriers just look wrong. What exactly are
On 9/4/19 10:19 AM, Peter Zijlstra wrote:
Adding Paul since RCU faces similar situations, i.e. raising softirq risks
scheduler deadlock in rcu_read_unlock_special() -- but RCU's solution is to
avoid raising the softirq and instead use irq_work.
Which is right.
Thanks Joel and Peter for
On Wed, Sep 04, 2019 at 10:19:19AM +0200, Peter Zijlstra wrote:
> On Wed, Sep 04, 2019 at 12:00:39AM -0400, Joel Fernandes wrote:
> > [ Resending since I messed up my last email's headers! ]
> >
> > On Tue, Sep 03, 2019 at 03:25:59PM +0200, Viktor Rosendahl wrote:
> > > This patch implements the
On Tue, 3 Sep 2019 15:25:59 +0200
Viktor Rosendahl wrote:
> +void latency_fsnotify_stop(void)
> +{
> + /* Make sure all CPUs see caller's previous actions to stop tracer */
> + smp_wmb();
These memory barriers just look wrong. What exactly are you trying to protect
here?
Where's the
On Wed, 4 Sep 2019 10:20:46 +0200
Peter Zijlstra wrote:
> On Tue, Sep 03, 2019 at 03:25:59PM +0200, Viktor Rosendahl wrote:
>
> > It seems like it would be possible to simply replace the calls to
> > latency_fsnotify_enable/disable() with calls to
> > start/stop_critical_timings(). However, the
On Wed, Sep 04, 2019 at 12:00:39AM -0400, Joel Fernandes wrote:
> [ Resending since I messed up my last email's headers! ]
>
> On Tue, Sep 03, 2019 at 03:25:59PM +0200, Viktor Rosendahl wrote:
> > This patch implements the feature that the tracing_max_latency file,
> > e.g.
On Tue, Sep 03, 2019 at 03:25:59PM +0200, Viktor Rosendahl wrote:
> It seems like it would be possible to simply replace the calls to
> latency_fsnotify_enable/disable() with calls to
> start/stop_critical_timings(). However, the main problem is that it
> would not work for the wakup tracer. The
On Wed, Sep 04, 2019 at 12:00:39AM -0400, Joel Fernandes wrote:
> [ Resending since I messed up my last email's headers! ]
>
> On Tue, Sep 03, 2019 at 03:25:59PM +0200, Viktor Rosendahl wrote:
> > This patch implements the feature that the tracing_max_latency file,
> > e.g.
[ Resending since I messed up my last email's headers! ]
On Tue, Sep 03, 2019 at 03:25:59PM +0200, Viktor Rosendahl wrote:
> This patch implements the feature that the tracing_max_latency file,
> e.g. /sys/kernel/debug/tracing/tracing_max_latency will receive
> notifications through the fsnotify
This patch implements the feature that the tracing_max_latency file,
e.g. /sys/kernel/debug/tracing/tracing_max_latency will receive
notifications through the fsnotify framework when a new latency is
available.
One particularly interesting use of this facility is when enabling
threshold tracing,
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