linux-kernel - Re: [PATCH v4 01/10] tools/libperf: introduce static poll file descriptors

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Message-ID: <20200531181912.GC881900@krava>
Date:   Sun, 31 May 2020 20:19:12 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 01/10] tools/libperf: introduce static poll file
 descriptors

On Mon, May 25, 2020 at 05:17:31PM +0300, Alexey Budankov wrote:

SBIP

> +int fdarray__add_stat(struct fdarray *fda, int fd, short revents)
> +{
> +	int pos = fda->nr_stat;
> +
> +	if (pos >= FDARRAY__STAT_ENTRIES_MAX)
> +		return -1;
> +
> +	fda->stat_entries[pos].fd = fd;
> +	fda->stat_entries[pos].events = revents;
> +	fda->nr_stat++;
> +
> +	return pos;
> +}
> +
>  int fdarray__filter(struct fdarray *fda, short revents,
>  		    void (*entry_destructor)(struct fdarray *fda, int fd, void *arg),
>  		    void *arg)
> @@ -113,7 +133,27 @@ int fdarray__filter(struct fdarray *fda, short revents,
>  
>  int fdarray__poll(struct fdarray *fda, int timeout)
>  {
> -	return poll(fda->entries, fda->nr, timeout);
> +	int nr, i, pos, res;
> +
> +	nr = fda->nr;
> +
> +	for (i = 0; i < fda->nr_stat; i++) {
> +		if (fda->stat_entries[i].fd != -1) {
> +			pos = fdarray__add(fda, fda->stat_entries[i].fd,
> +					   fda->stat_entries[i].events);
> +			if (pos >= 0)
> +				fda->priv[pos].idx = i;
> +		}
> +	}

hum, so every time we call evlist__poll we end up in here
adding more stuff to entries?

jirka

> +
> +	res = poll(fda->entries, fda->nr, timeout);
> +
> +	for (i = nr; i < fda->nr; i++)
> +		fda->stat_entries[fda->priv[i].idx] = fda->entries[i];
> +
> +	fda->nr = nr;
> +
> +	return res;
>  }

SNIP