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    SubjectRe: [PATCH V4 01/19] trace/osnoise: Do not follow tracing_cpumask
    On Thu, 21 Oct 2021 14:56:39 +0200
    Daniel Bristot de Oliveira <bristot@kernel.org> wrote:

    > In preparation to support multiple instances, decople the

    "decouple"

    > osnoise/timelat workload from instance specific tracing_cpumask.
    >
    > Different instances can have conflicing cpumasks, making osnoise

    "conflicting"

    May I suggest a spell check for your commit logs? ;-)

    > workload management needlessly complex. Osnoise already have its
    > global cpu mask.
    >
    > I also thought about using the first instance mask, but the
    > "first" instance could be removed before the others.
    >
    > This also fixes the problem that changing the tracing_mask was not
    > re-starting the trace.
    >
    > Cc: Steven Rostedt <rostedt@goodmis.org>
    > Cc: Ingo Molnar <mingo@redhat.com>
    > Cc: Tom Zanussi <zanussi@kernel.org>
    > Cc: Masami Hiramatsu <mhiramat@kernel.org>
    > Cc: Juri Lelli <juri.lelli@redhat.com>
    > Cc: Clark Williams <williams@redhat.com>
    > Cc: John Kacur <jkacur@redhat.com>
    > Cc: Peter Zijlstra <peterz@infradead.org>
    > Cc: Thomas Gleixner <tglx@linutronix.de>
    > Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    > Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
    > Cc: linux-rt-users@vger.kernel.org
    > Cc: linux-trace-devel@vger.kernel.org
    > Cc: linux-kernel@vger.kernel.org
    > Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
    > ---
    > kernel/trace/trace_osnoise.c | 25 +++++++------------------
    > 1 file changed, 7 insertions(+), 18 deletions(-)
    >
    > diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
    > index ce053619f289..7b1f8187764c 100644
    > --- a/kernel/trace/trace_osnoise.c
    > +++ b/kernel/trace/trace_osnoise.c
    > @@ -1553,13 +1553,10 @@ static int start_per_cpu_kthreads(struct trace_array *tr)
    >
    > cpus_read_lock();
    > /*
    > - * Run only on CPUs in which trace and osnoise are allowed to run.
    > + * Run only on online CPUs in which trace and osnoise are allowed to

    which trace and osnise? I thought we were removing "trace"?

    -- Steve

    > + * run.
    > */
    > - cpumask_and(current_mask, tr->tracing_cpumask, &osnoise_cpumask);
    > - /*
    > - * And the CPU is online.
    > - */
    > - cpumask_and(current_mask, cpu_online_mask, current_mask);
    > + cpumask_and(current_mask, cpu_online_mask, &osnoise_cpumask);
    >
    > for_each_possible_cpu(cpu)
    > per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
    > @@ -1580,10 +1577,8 @@ static int start_per_cpu_kthreads(struct trace_array *tr)
    > #ifdef CONFIG_HOTPLUG_CPU
    > static void osnoise_hotplug_workfn(struct work_struct *dummy)
    > {
    > - struct trace_array *tr = osnoise_trace;
    > unsigned int cpu = smp_processor_id();
    >
    > -
    > mutex_lock(&trace_types_lock);
    >
    > if (!osnoise_busy)
    > @@ -1595,9 +1590,6 @@ static void osnoise_hotplug_workfn(struct work_struct *dummy)
    > if (!cpumask_test_cpu(cpu, &osnoise_cpumask))
    > goto out_unlock;
    >
    > - if (!cpumask_test_cpu(cpu, tr->tracing_cpumask))
    > - goto out_unlock;
    > -
    > start_kthread(cpu);
    >
    > out_unlock:
    > @@ -1700,13 +1692,10 @@ static void osnoise_tracer_stop(struct trace_array *tr);
    > * interface to the osnoise trace. By default, it lists all CPUs,
    > * in this way, allowing osnoise threads to run on any online CPU
    > * of the system. It serves to restrict the execution of osnoise to the
    > - * set of CPUs writing via this interface. Note that osnoise also
    > - * respects the "tracing_cpumask." Hence, osnoise threads will run only
    > - * on the set of CPUs allowed here AND on "tracing_cpumask." Why not
    > - * have just "tracing_cpumask?" Because the user might be interested
    > - * in tracing what is running on other CPUs. For instance, one might
    > - * run osnoise in one HT CPU while observing what is running on the
    > - * sibling HT CPU.
    > + * set of CPUs writing via this interface. Why not use "tracing_cpumask"?
    > + * Because the user might be interested in tracing what is running on
    > + * other CPUs. For instance, one might run osnoise in one HT CPU
    > + * while observing what is running on the sibling HT CPU.
    > */
    > static ssize_t
    > osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,

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