linux-kernel - Re: [PATCH v2 3/4] perf record: enable runtime trace compression

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Message-ID: <20190212130902.GI775@krava>
Date:   Tue, 12 Feb 2019 14:09:02 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/4] perf record: enable runtime trace compression

On Mon, Feb 11, 2019 at 11:23:40PM +0300, Alexey Budankov wrote:

SNIP

> +	compress_fn = (record__comp_enabled(rec) ?
> +		perf_session__zstd_compress : perf_session__zstd_copy);
> +
>  	if (record__aio_enabled(rec))
>  		off = record__aio_get_pos(trace_fd);
>  
> @@ -799,11 +805,21 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
>  				map->flush = MMAP_FLUSH_DEFAULT;
>  			}
>  			if (!record__aio_enabled(rec)) {
> -				if (perf_mmap__push(map, rec, record__pushfn) != 0) {
> -					if (sync)
> -						map->flush = flush;
> -					rc = -1;
> -					goto out;
> +				if (!record__comp_enabled(rec)) {
> +					if (perf_mmap__push(map, rec, record__pushfn) != 0) {
> +						if (sync)
> +							map->flush = flush;
> +						rc = -1;
> +						goto out;
> +					}
> +				} else {
> +					if (perf_mmap__pack(map, rec, record__pushfn,
> +							compress_fn, session) != 0) {
> +						if (sync)
> +							map->flush = flush;
> +						rc = -1;
> +						goto out;
> +					}

I really dont like this.. the non-compression flow needs to stay untouched

why don't you overload the record__pushfn function for compression
processing and stash the data in there?

thanks,
jirka