Collect tid, period, callchain, and cgroup id and dump them when off-cpu
time threshold is reached.
We don't collect the off-cpu time twice (the delta), it's either in
direct samples, or accumulated samples that are dumped at the end of
perf.data.
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
---
tools/perf/util/bpf_skel/off_cpu.bpf.c | 83 ++++++++++++++++++++++++--
1 file changed, 78 insertions(+), 5 deletions(-)
diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
index dc6acafb9353..bf652c30b1c9 100644
--- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
+++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
@@ -18,10 +18,18 @@
#define MAX_STACKS 32
#define MAX_ENTRIES 102400
+#define MAX_CPUS 4096
+#define MAX_OFFCPU_LEN 37
+
+struct stack {
+ u64 array[MAX_STACKS];
+};
+
struct tstamp_data {
__u32 stack_id;
__u32 state;
__u64 timestamp;
+ struct stack stack;
};
struct offcpu_key {
@@ -39,6 +47,24 @@ struct {
__uint(max_entries, MAX_ENTRIES);
} stacks SEC(".maps");
+struct offcpu_data {
+ u64 array[MAX_OFFCPU_LEN];
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(__u32));
+ __uint(max_entries, MAX_CPUS);
+} offcpu_output SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(struct offcpu_data));
+ __uint(max_entries, 1);
+} offcpu_payload SEC(".maps");
+
struct {
__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
@@ -185,6 +211,39 @@ static inline int can_record(struct task_struct *t, int state)
return 1;
}
+static inline int copy_stack(struct stack *from, struct offcpu_data *to, int n)
+{
+ int len = 0;
+
+ for (int i = 0; i < MAX_STACKS && from->array[i]; ++i, ++len)
+ to->array[n + 2 + i] = from->array[i];
+
+ return len;
+}
+
+static int off_cpu_dump(void *ctx, struct offcpu_data *data, struct offcpu_key *key,
+ struct stack *stack, __u64 delta, __u64 timestamp)
+{
+ /* dump tid, period, callchain, and cgroup id */
+ int n = 0, len = 0;
+
+ data->array[n++] = (u64)key->tgid << 32 | key->pid;
+ data->array[n++] = delta;
+
+ /* data->array[n] is callchain->nr (updated later) */
+ data->array[n + 1] = PERF_CONTEXT_USER;
+ data->array[n + 2] = 0;
+ len = copy_stack(stack, data, n);
+
+ /* update length of callchain */
+ data->array[n] = len + 1;
+ n += len + 2;
+
+ data->array[n++] = key->cgroup_id;
+
+ return bpf_perf_event_output(ctx, &offcpu_output, BPF_F_CURRENT_CPU, data, n * sizeof(u64));
+}
+
static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
struct task_struct *next, int state)
{
@@ -209,6 +268,12 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
pelem->state = state;
pelem->stack_id = stack_id;
+ /*
+ * If stacks are successfully collected by bpf_get_stackid(), collect them once more
+ * in task_storage for direct off-cpu sample dumping
+ */
+ if (stack_id > 0 && bpf_get_stack(ctx, &pelem->stack, MAX_STACKS * sizeof(u64), BPF_F_USER_STACK)) {
+ }
+
next:
pelem = bpf_task_storage_get(&tstamp, next, NULL, 0);
@@ -223,11 +288,19 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
__u64 delta = ts - pelem->timestamp;
__u64 *total;
- total = bpf_map_lookup_elem(&off_cpu, &key);
- if (total)
- *total += delta;
- else
- bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
+ if (delta >= offcpu_thresh) {
+ int zero = 0;
+ struct offcpu_data *data = bpf_map_lookup_elem(&offcpu_payload, &zero);
+
+ if (data)
+ off_cpu_dump(ctx, data, &key, &pelem->stack, delta, pelem->timestamp);
+ } else {
+ total = bpf_map_lookup_elem(&off_cpu, &key);
+ if (total)
+ *total += delta;
+ else
+ bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
+ }
/* prevent to reuse the timestamp later */
pelem->timestamp = 0;
--
2.43.0On Fri, Nov 8, 2024 at 12:41 PM Howard Chu <howardchu95@gmail.com> wrote:
>
> Collect tid, period, callchain, and cgroup id and dump them when off-cpu
> time threshold is reached.
>
> We don't collect the off-cpu time twice (the delta), it's either in
> direct samples, or accumulated samples that are dumped at the end of
> perf.data.
>
> Suggested-by: Namhyung Kim <namhyung@kernel.org>
> Signed-off-by: Howard Chu <howardchu95@gmail.com>
> ---
> tools/perf/util/bpf_skel/off_cpu.bpf.c | 83 ++++++++++++++++++++++++--
> 1 file changed, 78 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> index dc6acafb9353..bf652c30b1c9 100644
> --- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
> +++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> @@ -18,10 +18,18 @@
> #define MAX_STACKS 32
> #define MAX_ENTRIES 102400
>
> +#define MAX_CPUS 4096
> +#define MAX_OFFCPU_LEN 37
> +
> +struct stack {
> + u64 array[MAX_STACKS];
> +};
> +
> struct tstamp_data {
> __u32 stack_id;
> __u32 state;
> __u64 timestamp;
> + struct stack stack;
> };
>
> struct offcpu_key {
> @@ -39,6 +47,24 @@ struct {
> __uint(max_entries, MAX_ENTRIES);
> } stacks SEC(".maps");
>
> +struct offcpu_data {
> + u64 array[MAX_OFFCPU_LEN];
> +};
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> + __uint(key_size, sizeof(__u32));
> + __uint(value_size, sizeof(__u32));
> + __uint(max_entries, MAX_CPUS);
> +} offcpu_output SEC(".maps");
Does patch 4 build without this definition? (we're in patch 5 here). I
think this should be in patch 4.
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
> + __uint(key_size, sizeof(__u32));
> + __uint(value_size, sizeof(struct offcpu_data));
> + __uint(max_entries, 1);
> +} offcpu_payload SEC(".maps");
> +
> struct {
> __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
> __uint(map_flags, BPF_F_NO_PREALLOC);
> @@ -185,6 +211,39 @@ static inline int can_record(struct task_struct *t, int state)
> return 1;
> }
>
> +static inline int copy_stack(struct stack *from, struct offcpu_data *to, int n)
> +{
> + int len = 0;
> +
> + for (int i = 0; i < MAX_STACKS && from->array[i]; ++i, ++len)
> + to->array[n + 2 + i] = from->array[i];
> +
> + return len;
> +}
> +
Dump is something of a generic name. Could you kernel-doc this
function to describe the behavior?
> +static int off_cpu_dump(void *ctx, struct offcpu_data *data, struct offcpu_key *key,
> + struct stack *stack, __u64 delta, __u64 timestamp)
> +{
> + /* dump tid, period, callchain, and cgroup id */
> + int n = 0, len = 0;
> +
> + data->array[n++] = (u64)key->tgid << 32 | key->pid;
> + data->array[n++] = delta;
> +
> + /* data->array[n] is callchain->nr (updated later) */
> + data->array[n + 1] = PERF_CONTEXT_USER;
> + data->array[n + 2] = 0;
> + len = copy_stack(stack, data, n);
> +
> + /* update length of callchain */
> + data->array[n] = len + 1;
> + n += len + 2;
> +
> + data->array[n++] = key->cgroup_id;
> +
> + return bpf_perf_event_output(ctx, &offcpu_output, BPF_F_CURRENT_CPU, data, n * sizeof(u64));
> +}
> +
> static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
> struct task_struct *next, int state)
> {
> @@ -209,6 +268,12 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
> pelem->state = state;
> pelem->stack_id = stack_id;
>
> + /*
> + * If stacks are successfully collected by bpf_get_stackid(), collect them once more
> + * in task_storage for direct off-cpu sample dumping
> + */
> + if (stack_id > 0 && bpf_get_stack(ctx, &pelem->stack, MAX_STACKS * sizeof(u64), BPF_F_USER_STACK)) {
> + }
Why the empty if?
> +
> next:
> pelem = bpf_task_storage_get(&tstamp, next, NULL, 0);
>
> @@ -223,11 +288,19 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
> __u64 delta = ts - pelem->timestamp;
> __u64 *total;
>
> - total = bpf_map_lookup_elem(&off_cpu, &key);
> - if (total)
> - *total += delta;
> - else
> - bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
> + if (delta >= offcpu_thresh) {
> + int zero = 0;
> + struct offcpu_data *data = bpf_map_lookup_elem(&offcpu_payload, &zero);
> +
> + if (data)
> + off_cpu_dump(ctx, data, &key, &pelem->stack, delta, pelem->timestamp);
> + } else {
> + total = bpf_map_lookup_elem(&off_cpu, &key);
> + if (total)
> + *total += delta;
> + else
> + bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
> + }
Looks good! :-)
Thanks,
Ian
>
> /* prevent to reuse the timestamp later */
> pelem->timestamp = 0;
> --
> 2.43.0
>
Hi Ian,
On Mon, Nov 11, 2024 at 9:54 AM Ian Rogers <irogers@google.com> wrote:
>
> On Fri, Nov 8, 2024 at 12:41 PM Howard Chu <howardchu95@gmail.com> wrote:
> >
> > Collect tid, period, callchain, and cgroup id and dump them when off-cpu
> > time threshold is reached.
> >
> > We don't collect the off-cpu time twice (the delta), it's either in
> > direct samples, or accumulated samples that are dumped at the end of
> > perf.data.
> >
> > Suggested-by: Namhyung Kim <namhyung@kernel.org>
> > Signed-off-by: Howard Chu <howardchu95@gmail.com>
> > ---
> > tools/perf/util/bpf_skel/off_cpu.bpf.c | 83 ++++++++++++++++++++++++--
> > 1 file changed, 78 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> > index dc6acafb9353..bf652c30b1c9 100644
> > --- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
> > +++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> > @@ -18,10 +18,18 @@
> > #define MAX_STACKS 32
> > #define MAX_ENTRIES 102400
> >
> > +#define MAX_CPUS 4096
> > +#define MAX_OFFCPU_LEN 37
> > +
> > +struct stack {
> > + u64 array[MAX_STACKS];
> > +};
> > +
> > struct tstamp_data {
> > __u32 stack_id;
> > __u32 state;
> > __u64 timestamp;
> > + struct stack stack;
> > };
> >
> > struct offcpu_key {
> > @@ -39,6 +47,24 @@ struct {
> > __uint(max_entries, MAX_ENTRIES);
> > } stacks SEC(".maps");
> >
> > +struct offcpu_data {
> > + u64 array[MAX_OFFCPU_LEN];
> > +};
> > +
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> > + __uint(key_size, sizeof(__u32));
> > + __uint(value_size, sizeof(__u32));
> > + __uint(max_entries, MAX_CPUS);
> > +} offcpu_output SEC(".maps");
>
> Does patch 4 build without this definition? (we're in patch 5 here). I
> think this should be in patch 4.
Okay sure thanks :)
>
> > +
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
> > + __uint(key_size, sizeof(__u32));
> > + __uint(value_size, sizeof(struct offcpu_data));
> > + __uint(max_entries, 1);
> > +} offcpu_payload SEC(".maps");
> > +
> > struct {
> > __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
> > __uint(map_flags, BPF_F_NO_PREALLOC);
> > @@ -185,6 +211,39 @@ static inline int can_record(struct task_struct *t, int state)
> > return 1;
> > }
> >
> > +static inline int copy_stack(struct stack *from, struct offcpu_data *to, int n)
> > +{
> > + int len = 0;
> > +
> > + for (int i = 0; i < MAX_STACKS && from->array[i]; ++i, ++len)
> > + to->array[n + 2 + i] = from->array[i];
> > +
> > + return len;
> > +}
> > +
>
> Dump is something of a generic name. Could you kernel-doc this
> function to describe the behavior?
Sure.
>
> > +static int off_cpu_dump(void *ctx, struct offcpu_data *data, struct offcpu_key *key,
> > + struct stack *stack, __u64 delta, __u64 timestamp)
> > +{
> > + /* dump tid, period, callchain, and cgroup id */
> > + int n = 0, len = 0;
> > +
> > + data->array[n++] = (u64)key->tgid << 32 | key->pid;
> > + data->array[n++] = delta;
> > +
> > + /* data->array[n] is callchain->nr (updated later) */
> > + data->array[n + 1] = PERF_CONTEXT_USER;
> > + data->array[n + 2] = 0;
> > + len = copy_stack(stack, data, n);
> > +
> > + /* update length of callchain */
> > + data->array[n] = len + 1;
> > + n += len + 2;
> > +
> > + data->array[n++] = key->cgroup_id;
> > +
> > + return bpf_perf_event_output(ctx, &offcpu_output, BPF_F_CURRENT_CPU, data, n * sizeof(u64));
> > +}
> > +
> > static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
> > struct task_struct *next, int state)
> > {
> > @@ -209,6 +268,12 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
> > pelem->state = state;
> > pelem->stack_id = stack_id;
> >
> > + /*
> > + * If stacks are successfully collected by bpf_get_stackid(), collect them once more
> > + * in task_storage for direct off-cpu sample dumping
> > + */
> > + if (stack_id > 0 && bpf_get_stack(ctx, &pelem->stack, MAX_STACKS * sizeof(u64), BPF_F_USER_STACK)) {
> > + }
>
> Why the empty if?
Forgot to say in the commit message, bpf_get_stack() has a return
value and if I don't use it I'll get result unused warning from clang,
so either this or:
int __attribute__((unused)) len;
len = bpf_get_stack(ctx, stack_p->array, MAX_STACKS * sizeof(u64),
We don't need error handling, it goes to "next:" naturally, there's no
code in between.
>
> > +
> > next:
> > pelem = bpf_task_storage_get(&tstamp, next, NULL, 0);
> >
> > @@ -223,11 +288,19 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
> > __u64 delta = ts - pelem->timestamp;
> > __u64 *total;
> >
> > - total = bpf_map_lookup_elem(&off_cpu, &key);
> > - if (total)
> > - *total += delta;
> > - else
> > - bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
> > + if (delta >= offcpu_thresh) {
> > + int zero = 0;
> > + struct offcpu_data *data = bpf_map_lookup_elem(&offcpu_payload, &zero);
> > +
> > + if (data)
> > + off_cpu_dump(ctx, data, &key, &pelem->stack, delta, pelem->timestamp);
> > + } else {
> > + total = bpf_map_lookup_elem(&off_cpu, &key);
> > + if (total)
> > + *total += delta;
> > + else
> > + bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
> > + }
>
> Looks good! :-)
>
> Thanks,
> Ian
>
> >
> > /* prevent to reuse the timestamp later */
> > pelem->timestamp = 0;
> > --
> > 2.43.0
> >
Thanks,
Howard
On Mon, Nov 11, 2024 at 10:05 AM Howard Chu <howardchu95@gmail.com> wrote:
>
> Hi Ian,
>
> On Mon, Nov 11, 2024 at 9:54 AM Ian Rogers <irogers@google.com> wrote:
> >
> > On Fri, Nov 8, 2024 at 12:41 PM Howard Chu <howardchu95@gmail.com> wrote:
> > >
> > > Collect tid, period, callchain, and cgroup id and dump them when off-cpu
> > > time threshold is reached.
> > >
> > > We don't collect the off-cpu time twice (the delta), it's either in
> > > direct samples, or accumulated samples that are dumped at the end of
> > > perf.data.
> > >
> > > Suggested-by: Namhyung Kim <namhyung@kernel.org>
> > > Signed-off-by: Howard Chu <howardchu95@gmail.com>
> > > ---
> > > tools/perf/util/bpf_skel/off_cpu.bpf.c | 83 ++++++++++++++++++++++++--
> > > 1 file changed, 78 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> > > index dc6acafb9353..bf652c30b1c9 100644
> > > --- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
> > > +++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> > > @@ -18,10 +18,18 @@
> > > #define MAX_STACKS 32
> > > #define MAX_ENTRIES 102400
> > >
> > > +#define MAX_CPUS 4096
> > > +#define MAX_OFFCPU_LEN 37
> > > +
> > > +struct stack {
> > > + u64 array[MAX_STACKS];
> > > +};
> > > +
> > > struct tstamp_data {
> > > __u32 stack_id;
> > > __u32 state;
> > > __u64 timestamp;
> > > + struct stack stack;
> > > };
> > >
> > > struct offcpu_key {
> > > @@ -39,6 +47,24 @@ struct {
> > > __uint(max_entries, MAX_ENTRIES);
> > > } stacks SEC(".maps");
> > >
> > > +struct offcpu_data {
> > > + u64 array[MAX_OFFCPU_LEN];
> > > +};
> > > +
> > > +struct {
> > > + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> > > + __uint(key_size, sizeof(__u32));
> > > + __uint(value_size, sizeof(__u32));
> > > + __uint(max_entries, MAX_CPUS);
> > > +} offcpu_output SEC(".maps");
> >
> > Does patch 4 build without this definition? (we're in patch 5 here). I
> > think this should be in patch 4.
>
> Okay sure thanks :)
>
> >
> > > +
> > > +struct {
> > > + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
> > > + __uint(key_size, sizeof(__u32));
> > > + __uint(value_size, sizeof(struct offcpu_data));
> > > + __uint(max_entries, 1);
> > > +} offcpu_payload SEC(".maps");
> > > +
> > > struct {
> > > __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
> > > __uint(map_flags, BPF_F_NO_PREALLOC);
> > > @@ -185,6 +211,39 @@ static inline int can_record(struct task_struct *t, int state)
> > > return 1;
> > > }
> > >
> > > +static inline int copy_stack(struct stack *from, struct offcpu_data *to, int n)
> > > +{
> > > + int len = 0;
> > > +
> > > + for (int i = 0; i < MAX_STACKS && from->array[i]; ++i, ++len)
> > > + to->array[n + 2 + i] = from->array[i];
> > > +
> > > + return len;
> > > +}
> > > +
> >
> > Dump is something of a generic name. Could you kernel-doc this
> > function to describe the behavior?
>
> Sure.
>
> >
> > > +static int off_cpu_dump(void *ctx, struct offcpu_data *data, struct offcpu_key *key,
> > > + struct stack *stack, __u64 delta, __u64 timestamp)
> > > +{
> > > + /* dump tid, period, callchain, and cgroup id */
> > > + int n = 0, len = 0;
> > > +
> > > + data->array[n++] = (u64)key->tgid << 32 | key->pid;
> > > + data->array[n++] = delta;
> > > +
> > > + /* data->array[n] is callchain->nr (updated later) */
> > > + data->array[n + 1] = PERF_CONTEXT_USER;
> > > + data->array[n + 2] = 0;
> > > + len = copy_stack(stack, data, n);
> > > +
> > > + /* update length of callchain */
> > > + data->array[n] = len + 1;
> > > + n += len + 2;
> > > +
> > > + data->array[n++] = key->cgroup_id;
> > > +
> > > + return bpf_perf_event_output(ctx, &offcpu_output, BPF_F_CURRENT_CPU, data, n * sizeof(u64));
> > > +}
> > > +
> > > static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
> > > struct task_struct *next, int state)
> > > {
> > > @@ -209,6 +268,12 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
> > > pelem->state = state;
> > > pelem->stack_id = stack_id;
> > >
> > > + /*
> > > + * If stacks are successfully collected by bpf_get_stackid(), collect them once more
> > > + * in task_storage for direct off-cpu sample dumping
> > > + */
> > > + if (stack_id > 0 && bpf_get_stack(ctx, &pelem->stack, MAX_STACKS * sizeof(u64), BPF_F_USER_STACK)) {
> > > + }
> >
> > Why the empty if?
>
> Forgot to say in the commit message, bpf_get_stack() has a return
> value and if I don't use it I'll get result unused warning from clang,
> so either this or:
> int __attribute__((unused)) len;
> len = bpf_get_stack(ctx, stack_p->array, MAX_STACKS * sizeof(u64),
>
> We don't need error handling, it goes to "next:" naturally, there's no
> code in between.
Perhaps capture that as a comment in the `if` and/or add a continue,
just to show that the code doesn't care about errors.
Thanks,
Ian
> >
> > > +
> > > next:
> > > pelem = bpf_task_storage_get(&tstamp, next, NULL, 0);
> > >
> > > @@ -223,11 +288,19 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
> > > __u64 delta = ts - pelem->timestamp;
> > > __u64 *total;
> > >
> > > - total = bpf_map_lookup_elem(&off_cpu, &key);
> > > - if (total)
> > > - *total += delta;
> > > - else
> > > - bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
> > > + if (delta >= offcpu_thresh) {
> > > + int zero = 0;
> > > + struct offcpu_data *data = bpf_map_lookup_elem(&offcpu_payload, &zero);
> > > +
> > > + if (data)
> > > + off_cpu_dump(ctx, data, &key, &pelem->stack, delta, pelem->timestamp);
> > > + } else {
> > > + total = bpf_map_lookup_elem(&off_cpu, &key);
> > > + if (total)
> > > + *total += delta;
> > > + else
> > > + bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
> > > + }
> >
> > Looks good! :-)
> >
> > Thanks,
> > Ian
> >
> > >
> > > /* prevent to reuse the timestamp later */
> > > pelem->timestamp = 0;
> > > --
> > > 2.43.0
> > >
>
> Thanks,
> Howard
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