linux-kernel - Re: [PATCH v7 2/2]: perf record: enable asynchronous trace writing

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Date:   Thu, 6 Sep 2018 13:04:00 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 2/2]: perf record: enable asynchronous trace writing

On Wed, Sep 05, 2018 at 10:39:25AM +0300, Alexey Budankov wrote:

SNIP

> -static int record__pushfn(void *to, void *bf, size_t size)
> +static int record__pushfn(void *to, struct aiocb *cblock, void *data, size_t size)
>  {
> +	off_t off;
>  	struct record *rec = to;
> +	int ret, trace_fd = rec->session->data->file.fd;
>  
>  	rec->samples++;
> -	return record__write(rec, bf, size);
> +
> +	off =
> +	lseek(trace_fd, 0, SEEK_CUR);
> +	lseek(trace_fd, off + size, SEEK_SET);
> +
> +	ret = record__aio_write(cblock, trace_fd, data, size, off);
> +	if (!ret) {
> +		rec->bytes_written += size;
> +		if (switch_output_size(rec))
> +			trigger_hit(&switch_output_trigger);

why do you need to call switch output from here?

jirka