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Date:   Mon, 25 Jul 2022 18:39:26 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Yang Jihong <yangjihong1@huawei.com>
Cc:     peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com,
        alexander.shishkin@linux.intel.com, jolsa@kernel.org,
        namhyung@kernel.org, pc@us.ibm.com, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org
Subject: Re: [RFC v3 15/17] perf kwork: Add irq trace bpf support
Message-ID: <Yt8NjtZUnynstEXt@kernel.org>
References: <20220709015033.38326-1-yangjihong1@huawei.com>
 <20220709015033.38326-16-yangjihong1@huawei.com>
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Em Sat, Jul 09, 2022 at 09:50:31AM +0800, Yang Jihong escreveu:
> Implements irq trace bpf function.
> 
> Test cases:
> Trace irq without filter:
> 
>   # perf kwork -k irq rep -b
>   Starting trace, Hit <Ctrl+C> to stop and report

That is cool, works like a charm :-) Lemme go back testing the rest...

- Arnaldo

>   ^C
>     Kwork Name                     | Cpu  | Total Runtime | Count     | Max runtime   | Max runtime start   | Max runtime end     |
>    --------------------------------------------------------------------------------------------------------------------------------
>     virtio0-requests:25            | 0000 |     31.026 ms |       285 |      1.493 ms |     110326.049963 s |     110326.051456 s |
>     eth0:10                        | 0002 |      7.875 ms |        96 |      1.429 ms |     110313.916835 s |     110313.918264 s |
>     ata_piix:14                    | 0002 |      2.510 ms |        28 |      0.396 ms |     110331.367987 s |     110331.368383 s |
>    --------------------------------------------------------------------------------------------------------------------------------
> 
> Trace irq with cpu filter:
> 
>   # perf kwork -k irq rep -b -C 0
>   Starting trace, Hit <Ctrl+C> to stop and report
>   ^C
>     Kwork Name                     | Cpu  | Total Runtime | Count     | Max runtime   | Max runtime start   | Max runtime end     |
>    --------------------------------------------------------------------------------------------------------------------------------
>     virtio0-requests:25            | 0000 |     34.288 ms |       282 |      2.061 ms |     110358.078968 s |     110358.081029 s |
>    --------------------------------------------------------------------------------------------------------------------------------
> 
> Trace irq with name filter:
> 
>   # perf kwork -k irq rep -b -n eth0
>   Starting trace, Hit <Ctrl+C> to stop and report
>   ^C
>     Kwork Name                     | Cpu  | Total Runtime | Count     | Max runtime   | Max runtime start   | Max runtime end     |
>    --------------------------------------------------------------------------------------------------------------------------------
>     eth0:10                        | 0002 |      2.184 ms |        21 |      0.572 ms |     110386.541699 s |     110386.542271 s |
>    --------------------------------------------------------------------------------------------------------------------------------
> 
> Trace irq with summary:
> 
>   # perf kwork -k irq rep -b -S
>   Starting trace, Hit <Ctrl+C> to stop and report
>   ^C
>     Kwork Name                     | Cpu  | Total Runtime | Count     | Max runtime   | Max runtime start   | Max runtime end     |
>    --------------------------------------------------------------------------------------------------------------------------------
>     virtio0-requests:25            | 0000 |     42.923 ms |       285 |      1.181 ms |     110418.128867 s |     110418.130049 s |
>     eth0:10                        | 0002 |      2.085 ms |        20 |      0.668 ms |     110416.002935 s |     110416.003603 s |
>     ata_piix:14                    | 0002 |      0.970 ms |         4 |      0.656 ms |     110424.034482 s |     110424.035138 s |
>    --------------------------------------------------------------------------------------------------------------------------------
>     Total count            :       309
>     Total runtime   (msec) :    45.977 (0.003% load average)
>     Total time span (msec) : 17017.655
>    --------------------------------------------------------------------------------------------------------------------------------
> 
> Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
> ---
>  tools/perf/util/bpf_kwork.c                |  40 +++++-
>  tools/perf/util/bpf_skel/kwork_trace.bpf.c | 150 +++++++++++++++++++++
>  2 files changed, 189 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/bpf_kwork.c b/tools/perf/util/bpf_kwork.c
> index 433bfadd3af1..08252fcda1a4 100644
> --- a/tools/perf/util/bpf_kwork.c
> +++ b/tools/perf/util/bpf_kwork.c
> @@ -62,9 +62,47 @@ void perf_kwork__trace_finish(void)
>  	skel->bss->enabled = 0;
>  }
>  
> +static int get_work_name_from_map(struct work_key *key, char **ret_name)
> +{
> +	char name[MAX_KWORKNAME] = { 0 };
> +	int fd = bpf_map__fd(skel->maps.perf_kwork_names);
> +
> +	*ret_name = NULL;
> +
> +	if (fd < 0) {
> +		pr_debug("Invalid names map fd\n");
> +		return 0;
> +	}
> +
> +	if ((bpf_map_lookup_elem(fd, key, name) == 0) && (strlen(name) != 0)) {
> +		*ret_name = strdup(name);
> +		if (*ret_name == NULL) {
> +			pr_err("Failed to copy work name\n");
> +			return -1;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static void irq_load_prepare(struct perf_kwork *kwork)
> +{
> +	if (kwork->report == KWORK_REPORT_RUNTIME) {
> +		bpf_program__set_autoload(
> +			skel->progs.report_irq_handler_entry, true);
> +		bpf_program__set_autoload(
> +			skel->progs.report_irq_handler_exit, true);
> +	}
> +}
> +
> +static struct kwork_class_bpf kwork_irq_bpf = {
> +	.load_prepare  = irq_load_prepare,
> +	.get_work_name = get_work_name_from_map,
> +};
> +
>  static struct kwork_class_bpf *
>  kwork_class_bpf_supported_list[KWORK_CLASS_MAX] = {
> -	[KWORK_CLASS_IRQ]       = NULL,
> +	[KWORK_CLASS_IRQ]       = &kwork_irq_bpf,
>  	[KWORK_CLASS_SOFTIRQ]   = NULL,
>  	[KWORK_CLASS_WORKQUEUE] = NULL,
>  };
> diff --git a/tools/perf/util/bpf_skel/kwork_trace.bpf.c b/tools/perf/util/bpf_skel/kwork_trace.bpf.c
> index 36112be831e3..1925407d1c16 100644
> --- a/tools/perf/util/bpf_skel/kwork_trace.bpf.c
> +++ b/tools/perf/util/bpf_skel/kwork_trace.bpf.c
> @@ -71,4 +71,154 @@ int enabled = 0;
>  int has_cpu_filter = 0;
>  int has_name_filter = 0;
>  
> +static __always_inline int local_strncmp(const char *s1,
> +					 unsigned int sz, const char *s2)
> +{
> +	int ret = 0;
> +	unsigned int i;
> +
> +	for (i = 0; i < sz; i++) {
> +		ret = (unsigned char)s1[i] - (unsigned char)s2[i];
> +		if (ret || !s1[i] || !s2[i])
> +			break;
> +	}
> +
> +	return ret;
> +}
> +
> +static __always_inline int trace_event_match(struct work_key *key, char *name)
> +{
> +	__u8 *cpu_val;
> +	char *name_val;
> +	__u32 zero = 0;
> +	__u32 cpu = bpf_get_smp_processor_id();
> +
> +	if (!enabled)
> +		return 0;
> +
> +	if (has_cpu_filter) {
> +		cpu_val = bpf_map_lookup_elem(&perf_kwork_cpu_filter, &cpu);
> +		if (!cpu_val)
> +			return 0;
> +	}
> +
> +	if (has_name_filter && (name != NULL)) {
> +		name_val = bpf_map_lookup_elem(&perf_kwork_name_filter, &zero);
> +		if (name_val &&
> +		    (local_strncmp(name_val, MAX_KWORKNAME, name) != 0)) {
> +			return 0;
> +		}
> +	}
> +
> +	return 1;
> +}
> +
> +static __always_inline void do_update_time(void *map, struct work_key *key,
> +					   __u64 time_start, __u64 time_end)
> +{
> +	struct report_data zero, *data;
> +	__s64 delta = time_end - time_start;
> +
> +	if (delta < 0)
> +		return;
> +
> +	data = bpf_map_lookup_elem(map, key);
> +	if (!data) {
> +		__builtin_memset(&zero, 0, sizeof(zero));
> +		bpf_map_update_elem(map, key, &zero, BPF_NOEXIST);
> +		data = bpf_map_lookup_elem(map, key);
> +		if (!data)
> +			return;
> +	}
> +
> +	if ((delta > data->max_time) ||
> +	    (data->max_time == 0)) {
> +		data->max_time       = delta;
> +		data->max_time_start = time_start;
> +		data->max_time_end   = time_end;
> +	}
> +
> +	data->total_time += delta;
> +	data->nr++;
> +}
> +
> +static __always_inline void do_update_timestart(void *map, struct work_key *key)
> +{
> +	__u64 ts = bpf_ktime_get_ns();
> +
> +	bpf_map_update_elem(map, key, &ts, BPF_ANY);
> +}
> +
> +static __always_inline void do_update_timeend(void *report_map, void *time_map,
> +					      struct work_key *key)
> +{
> +	__u64 *time = bpf_map_lookup_elem(time_map, key);
> +
> +	if (time) {
> +		bpf_map_delete_elem(time_map, key);
> +		do_update_time(report_map, key, *time, bpf_ktime_get_ns());
> +	}
> +}
> +
> +static __always_inline void do_update_name(void *map,
> +					   struct work_key *key, char *name)
> +{
> +	if (!bpf_map_lookup_elem(map, key))
> +		bpf_map_update_elem(map, key, name, BPF_ANY);
> +}
> +
> +static __always_inline int update_timestart_and_name(void *time_map,
> +						     void *names_map,
> +						     struct work_key *key,
> +						     char *name)
> +{
> +	if (!trace_event_match(key, name))
> +		return 0;
> +
> +	do_update_timestart(time_map, key);
> +	do_update_name(names_map, key, name);
> +
> +	return 0;
> +}
> +
> +static __always_inline int update_timeend(void *report_map,
> +					  void *time_map, struct work_key *key)
> +{
> +	if (!trace_event_match(key, NULL))
> +		return 0;
> +
> +	do_update_timeend(report_map, time_map, key);
> +
> +	return 0;
> +}
> +
> +SEC("tracepoint/irq/irq_handler_entry")
> +int report_irq_handler_entry(struct trace_event_raw_irq_handler_entry *ctx)
> +{
> +	char name[MAX_KWORKNAME];
> +	struct work_key key = {
> +		.type = KWORK_CLASS_IRQ,
> +		.cpu  = bpf_get_smp_processor_id(),
> +		.id   = (__u64)ctx->irq,
> +	};
> +	void *name_addr = (void *)ctx + (ctx->__data_loc_name & 0xffff);
> +
> +	bpf_probe_read_kernel_str(name, sizeof(name), name_addr);
> +
> +	return update_timestart_and_name(&perf_kwork_time,
> +					 &perf_kwork_names, &key, name);
> +}
> +
> +SEC("tracepoint/irq/irq_handler_exit")
> +int report_irq_handler_exit(struct trace_event_raw_irq_handler_exit *ctx)
> +{
> +	struct work_key key = {
> +		.type = KWORK_CLASS_IRQ,
> +		.cpu  = bpf_get_smp_processor_id(),
> +		.id   = (__u64)ctx->irq,
> +	};
> +
> +	return update_timeend(&perf_kwork_report, &perf_kwork_time, &key);
> +}
> +
>  char LICENSE[] SEC("license") = "Dual BSD/GPL";
> -- 
> 2.30.GIT

-- 

- Arnaldo