2020-07-30 08:31:43

by Kevin Hao

Subject: [PATCH 1/2] tracing/hwlat: Drop the duplicate assignment in start_kthread()

We have set 'current_mask' to '&save_cpumask' in its declaration,
so there is no need to assign again.

Signed-off-by: Kevin Hao <[email protected]>
---
kernel/trace/trace_hwlat.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index e2be7bb7ef7e..ddb528a6cd51 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -371,7 +371,6 @@ static int start_kthread(struct trace_array *tr)
return 0;

/* Just pick the first CPU on first iteration */
- current_mask = &save_cpumask;
get_online_cpus();
cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);
put_online_cpus();
--
2.26.2

2020-07-30 08:31:48

by Kevin Hao

Subject: [PATCH 2/2] tracing/hwlat: Honor the tracing_cpumask

In calculation of the cpu mask for the hwlat kernel thread, the wrong
cpu mask is used instead of the tracing_cpumask, this causes the
tracing/tracing_cpumask useless for hwlat tracer. Fixes it.

Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Kevin Hao <[email protected]>
---
kernel/trace/trace_hwlat.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index ddb528a6cd51..17873e5d0353 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -283,6 +283,7 @@ static bool disable_migrate;
static void move_to_next_cpu(void)
{
struct cpumask *current_mask = &save_cpumask;
+ struct trace_array *tr = hwlat_trace;
int next_cpu;

if (disable_migrate)
@@ -296,7 +297,7 @@ static void move_to_next_cpu(void)
goto disable;

get_online_cpus();
- cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);
+ cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
next_cpu = cpumask_next(smp_processor_id(), current_mask);
put_online_cpus();

@@ -372,7 +373,7 @@ static int start_kthread(struct trace_array *tr)

/* Just pick the first CPU on first iteration */
get_online_cpus();
- cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);
+ cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
put_online_cpus();
next_cpu = cpumask_first(current_mask);

--
2.26.2