linux-kernel - Re: [PATCH v5 08/10] perf report: implement record trace decompression

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Date:   Tue, 5 Mar 2019 13:25:29 +0100
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 v5 08/10] perf report: implement record trace
 decompression

On Fri, Mar 01, 2019 at 07:06:23PM +0300, Alexey Budankov wrote:

SNIP

> +static int __perf_session__process_decomp_events(struct perf_session *session)
> +{
> +	s64 skip;
> +	u64 size, file_pos = 0;
> +	union perf_event *event;
> +	struct decomp *decomp = session->decomp_last;
> +
> +	if (!decomp)
> +		return 0;
> +
> +	while (decomp->head < decomp->size && !session_done()) {
> +		event = fetch_mmaped_event(session, decomp->head, decomp->size, decomp->data);
> +		if (!event)
> +			break;
> +
> +		size = event->header.size;
> +		if (size < sizeof(struct perf_event_header) ||
> +		    (skip = perf_session__process_event(session, event, file_pos)) < 0) {
> +			pr_err("%#" PRIx64 " [%#x]: failed to process type: %d\n",
> +				decomp->file_pos + decomp->head, event->header.size, event->header.type);
> +			return -EINVAL;
> +		}
> +
> +		if (skip)
> +			size += skip;
> +
> +		decomp->head += size;
> +	}
> +
> +	return 0;
> +}
> +
>  /*
>   * On 64bit we can mmap the data file in one go. No need for tiny mmap
>   * slices. On 32bit we use 32MB.
> @@ -1933,6 +2051,10 @@ reader__process_events(struct reader *rd, struct perf_session *session,
>  	head += size;
>  	file_pos += size;
>  
> +	err = __perf_session__process_decomp_events(session);
> +	if (err)
> +		goto out;

why don't we process decompressed events directly from the 
perf_session__process_compressed_event callback?

there would be no need for 'struct decomp' list logic

jirka