linux-kernel - Re: [PATCH 05/17] perf tools: Add ordered_events

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Date:	Fri, 13 Jun 2014 21:05:05 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Jiri Olsa <jolsa@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Jean Pihet <jean.pihet@...aro.org>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 05/17] perf tools: Add ordered_events_(get|put)
 interface

2014-06-13 (금), 00:08 +0200, Jiri Olsa:
> +#define MAX_SAMPLE_BUFFER	(64 * 1024 / sizeof(struct ordered_event))
> +static struct ordered_event *alloc_event(struct ordered_events_queue *q)
> +{
> +	struct list_head *cache = &q->cache;
> +	struct ordered_event *new;
> +
> +	if (!list_empty(cache)) {
> +		new = list_entry(cache->next, struct ordered_event, list);
> +		list_del(&new->list);
> +	} else if (q->buffer) {
> +		new = q->buffer + q->buffer_idx;
> +		if (++q->buffer_idx == MAX_SAMPLE_BUFFER)
> +			q->buffer = NULL;
> +	} else {
> +		q->buffer = malloc(MAX_SAMPLE_BUFFER * sizeof(*new));
> +		if (!q->buffer)
> +			return NULL;
> +		list_add(&q->buffer->list, &q->to_free);
> +		q->buffer_idx = 2;
> +		new = q->buffer + 1;

Hmm.. can we add a comment that the first entry is abused to maintain
the to_free list?


> +	}
> +
> +	return new;
> +}
> +
> +static struct ordered_event*
> +ordered_events_get(struct ordered_events_queue *q, u64 timestamp)
> +{
> +	struct ordered_event *new;
> +
> +	new = alloc_event(q);
> +	if (new) {
> +		new->timestamp = timestamp;
> +		queue_event(q, new);
> +	}
> +
> +	return new;
> +}
> +
> +static void
> +ordered_event_put(struct ordered_events_queue *q, struct ordered_event *iter)
> +{
> +	list_del(&iter->list);
> +	list_add(&iter->list, &q->cache);

list_move(&iter->list, &q->cache) ?

> +	q->nr_events--;
> +}


[SNIP]
> @@ -639,29 +681,13 @@ int perf_session_queue_event(struct perf_session *s, union perf_event *event,
>  		return -EINVAL;
>  	}
>  
> -	if (!list_empty(cache)) {
> -		new = list_entry(cache->next, struct ordered_event, list);
> -		list_del(&new->list);
> -	} else if (q->buffer) {
> -		new = q->buffer + q->buffer_idx;
> -		if (++q->buffer_idx == MAX_SAMPLE_BUFFER)
> -			q->buffer = NULL;
> -	} else {
> -		q->buffer = malloc(MAX_SAMPLE_BUFFER * sizeof(*new));
> -		if (!q->buffer)
> -			return -ENOMEM;
> -		list_add(&q->buffer->list, &q->to_free);
> -		q->buffer_idx = 2;
> -		new = q->buffer + 1;
> +	new = ordered_events_get(q, timestamp);
> +	if (new) {
> +		new->file_offset = file_offset;
> +		new->event = event;
>  	}

What about make it like below:

	if (!new)
		return -ENOMEM;

This way we can share more of the original code.

Thanks,
Namhyung


>  
> -	new->timestamp = timestamp;
> -	new->file_offset = file_offset;
> -	new->event = event;
> -
> -	__queue_event(new, s);
> -
> -	return 0;
> +	return new ? 0 : -ENOMEM;
>  }
>  
>  static void callchain__printf(struct perf_sample *sample)



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