Re: [PATCH 2/4] perf lock contention: Use lock_stat_find{,new}

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Wed, Feb 01, 2023 at 09:04:53PM -0800, Namhyung Kim escreveu:
> This is a preparation work to support complex keys of BPF maps.  Now it
> has single value key according to the aggregation mode like stack_id or
> pid.  But we want to use a combination of those keys.
> 
> Then lock_contention_read() should still aggregate the result based on
> the key that was requested by user.  The other key info will be used for
> filtering.
> 
> So instead of creating a lock_stat entry always, Check if it's already
> there using lock_stat_find() first.

Hey, try building without libtraceevent-devel installed, should be
equivalent to NO_LIBTRACEEVENT=1.

At this point I think you should move bpf_lock_contention.o to inside
that CONFIG_LIBTRACEEVENT if block.

perf-$(CONFIG_PERF_BPF_SKEL) += bpf_lock_contention.o

ifeq ($(CONFIG_LIBTRACEEVENT),y)
  perf-$(CONFIG_PERF_BPF_SKEL) += bpf_kwork.o
endif

I'm removing this series from tmp.perf/core for now.

- Arnaldo
 
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/perf/builtin-lock.c             |  4 +--
>  tools/perf/util/bpf_lock_contention.c | 41 ++++++++++++++++-----------
>  tools/perf/util/lock-contention.h     |  3 ++
>  3 files changed, 30 insertions(+), 18 deletions(-)
> 
> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> index 216a9a252bf4..0593c6e636c6 100644
> --- a/tools/perf/builtin-lock.c
> +++ b/tools/perf/builtin-lock.c
> @@ -465,7 +465,7 @@ static struct lock_stat *pop_from_result(void)
>  	return container_of(node, struct lock_stat, rb);
>  }
>  
> -static struct lock_stat *lock_stat_find(u64 addr)
> +struct lock_stat *lock_stat_find(u64 addr)
>  {
>  	struct hlist_head *entry = lockhashentry(addr);
>  	struct lock_stat *ret;
> @@ -477,7 +477,7 @@ static struct lock_stat *lock_stat_find(u64 addr)
>  	return NULL;
>  }
>  
> -static struct lock_stat *lock_stat_findnew(u64 addr, const char *name, int flags)
> +struct lock_stat *lock_stat_findnew(u64 addr, const char *name, int flags)
>  {
>  	struct hlist_head *entry = lockhashentry(addr);
>  	struct lock_stat *ret, *new;
> diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
> index 967ce168f163..c6f2db603d5a 100644
> --- a/tools/perf/util/bpf_lock_contention.c
> +++ b/tools/perf/util/bpf_lock_contention.c
> @@ -254,12 +254,34 @@ int lock_contention_read(struct lock_contention *con)
>  	prev_key = NULL;
>  	while (!bpf_map_get_next_key(fd, prev_key, &key)) {
>  		s32 stack_id;
> +		const char *name;
>  
>  		/* to handle errors in the loop body */
>  		err = -1;
>  
>  		bpf_map_lookup_elem(fd, &key, &data);
> -		st = zalloc(sizeof(*st));
> +
> +		if (con->save_callstack) {
> +			stack_id = key.aggr_key;
> +			bpf_map_lookup_elem(stack, &stack_id, stack_trace);
> +		}
> +
> +		st = lock_stat_find(key.aggr_key);
> +		if (st != NULL) {
> +			st->wait_time_total += data.total_time;
> +			if (st->wait_time_max < data.max_time)
> +				st->wait_time_max = data.max_time;
> +			if (st->wait_time_min > data.min_time)
> +				st->wait_time_min = data.min_time;
> +
> +			st->nr_contended += data.count;
> +			if (st->nr_contended)
> +				st->avg_wait_time = st->wait_time_total / st->nr_contended;
> +			goto next;
> +		}
> +
> +		name = lock_contention_get_name(con, &key, stack_trace);
> +		st = lock_stat_findnew(key.aggr_key, name, data.flags);
>  		if (st == NULL)
>  			break;
>  
> @@ -272,14 +294,6 @@ int lock_contention_read(struct lock_contention *con)
>  			st->avg_wait_time = data.total_time / data.count;
>  
>  		st->flags = data.flags;
> -		st->addr = key.aggr_key;
> -
> -		stack_id = key.aggr_key;
> -		bpf_map_lookup_elem(stack, &stack_id, stack_trace);
> -
> -		st->name = strdup(lock_contention_get_name(con, &key, stack_trace));
> -		if (st->name == NULL)
> -			break;
>  
>  		if (con->save_callstack) {
>  			st->callstack = memdup(stack_trace, stack_size);
> @@ -287,19 +301,14 @@ int lock_contention_read(struct lock_contention *con)
>  				break;
>  		}
>  
> -		hlist_add_head(&st->hash_entry, con->result);
> +next:
>  		prev_key = &key;
>  
> -		/* we're fine now, reset the values */
> -		st = NULL;
> +		/* we're fine now, reset the error */
>  		err = 0;
>  	}
>  
>  	free(stack_trace);
> -	if (st) {
> -		free(st->name);
> -		free(st);
> -	}
>  
>  	return err;
>  }
> diff --git a/tools/perf/util/lock-contention.h b/tools/perf/util/lock-contention.h
> index 17e594d57a61..39d5bfc77f4e 100644
> --- a/tools/perf/util/lock-contention.h
> +++ b/tools/perf/util/lock-contention.h
> @@ -65,6 +65,9 @@ struct lock_stat {
>   */
>  #define MAX_LOCK_DEPTH 48
>  
> +struct lock_stat *lock_stat_find(u64 addr);
> +struct lock_stat *lock_stat_findnew(u64 addr, const char *name, int flags);
> +
>  /*
>   * struct lock_seq_stat:
>   * Place to put on state of one lock sequence
> -- 
> 2.39.1.456.gfc5497dd1b-goog
> 

-- 

- Arnaldo