[PATCH 1/4] dma-buf/fence-chain: Report time spent in wait_* test cases

From: Janusz Krzysztofik
Date: Thu Aug 14 2025 - 05:53:57 EST


CI results indicate excessive time spent on processing of wait_backward
selftest. For easy comparison, report processing time of each wait_* test
case.

Suggested-by: Chris Wilson <chris.p.wilson@xxxxxxxxxxxxxxx>
Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@xxxxxxxxxxxxxxx>
---
drivers/dma-buf/st-dma-fence-chain.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/drivers/dma-buf/st-dma-fence-chain.c b/drivers/dma-buf/st-dma-fence-chain.c
index ed4b323886e43..80598da9237af 100644
--- a/drivers/dma-buf/st-dma-fence-chain.c
+++ b/drivers/dma-buf/st-dma-fence-chain.c
@@ -572,6 +572,7 @@ static int wait_forward(void *arg)
{
struct fence_chains fc;
struct task_struct *tsk;
+ ktime_t dt;
int err;
int i;

@@ -587,8 +588,12 @@ static int wait_forward(void *arg)
get_task_struct(tsk);
yield_to(tsk, true);

+ dt = -ktime_get();
for (i = 0; i < fc.chain_length; i++)
dma_fence_signal(fc.fences[i]);
+ dt += ktime_get();
+
+ pr_info("%s: %d signals in %llu ns\n", __func__, fc.chain_length, ktime_to_ns(dt));

err = kthread_stop_put(tsk);

@@ -601,6 +606,7 @@ static int wait_backward(void *arg)
{
struct fence_chains fc;
struct task_struct *tsk;
+ ktime_t dt;
int err;
int i;

@@ -616,8 +622,12 @@ static int wait_backward(void *arg)
get_task_struct(tsk);
yield_to(tsk, true);

+ dt = -ktime_get();
for (i = fc.chain_length; i--; )
dma_fence_signal(fc.fences[i]);
+ dt += ktime_get();
+
+ pr_info("%s: %d signals in %llu ns\n", __func__, fc.chain_length, ktime_to_ns(dt));

err = kthread_stop_put(tsk);

@@ -646,6 +656,7 @@ static int wait_random(void *arg)
{
struct fence_chains fc;
struct task_struct *tsk;
+ ktime_t dt;
int err;
int i;

@@ -663,8 +674,12 @@ static int wait_random(void *arg)
get_task_struct(tsk);
yield_to(tsk, true);

+ dt = -ktime_get();
for (i = 0; i < fc.chain_length; i++)
dma_fence_signal(fc.fences[i]);
+ dt += ktime_get();
+
+ pr_info("%s: %d signals in %llu ns\n", __func__, fc.chain_length, ktime_to_ns(dt));

err = kthread_stop_put(tsk);

--
2.50.1