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Date:   Mon, 4 Oct 2021 15:53:40 +0200
From:   Jiri Olsa <jolsa@redhat.com>
To:     Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Andi Kleen <ak@linux.intel.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Alexander Antonov <alexander.antonov@linux.intel.com>,
        Alexei Budankov <abudankov@huawei.com>,
        Riccardo Mancini <rickyman7@gmail.com>
Subject: Re: [PATCH 3/6] perf session: Introduce decompressor into reader
 object
Message-ID: <YVsHZCv6mGdO7jGv@krava>
References: <cover.1632900802.git.alexey.v.bayduraev@linux.intel.com>
 <92dd8a7b9cf92f856cdd38114fc33eda4c5aba1a.1632900802.git.alexey.v.bayduraev@linux.intel.com>
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On Wed, Sep 29, 2021 at 11:41:51AM +0300, Alexey Bayduraev wrote:
> Introduce decompressor into reader object so that decompression
> could be executed separately for each data file. Adding active_reader
> into perf_session object to select current decompressor.
> 
> Acked-by: Namhyung Kim <namhyung@gmail.com>
> Reviewed-by: Riccardo Mancini <rickyman7@gmail.com>
> Tested-by: Riccardo Mancini <rickyman7@gmail.com>
> Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
> ---
>  tools/perf/util/session.c | 48 +++++++++++++++++++++++++++++----------
>  tools/perf/util/session.h |  2 ++
>  2 files changed, 38 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 262efc18caac..3bea0830b3b8 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -71,6 +71,9 @@ struct reader {
>  	u64		 data_offset;
>  	reader_cb_t	 process;
>  	bool		 in_place_update;
> +	struct zstd_data zstd_data;
> +	struct decomp	 *decomp;
> +	struct decomp	 *decomp_last;

so reader and session share the same fields, I think it'd be better
if we put them to the new struct.. perhaps have something like:

  struct compress {
    struct zstd_data zstd_data;
    struct decomp    *decomp;
    struct decomp    *decomp_last;
  }

  struct session {
    ...
    struct compress *compress;   /* initialized to &compress_lcl */
    struct compress compress_lcl;
  }

  struct reader {
    ...
    struct compress compress;
  }


reader__process_events will set session->compress to &reader->compress

perf_session__process_compressed_event would always work with
compress pointer.. this would ease up following code as well

also I don't like the idea sharing the whole reader with session,
it'll be abused.. let's give up gradually ;-)

thanks,
jirka

>  	struct reader_state state;
>  };
>  
> @@ -82,7 +85,10 @@ static int perf_session__process_compressed_event(struct perf_session *session,
>  	size_t decomp_size, src_size;
>  	u64 decomp_last_rem = 0;
>  	size_t mmap_len, decomp_len = session->header.env.comp_mmap_len;
> -	struct decomp *decomp, *decomp_last = session->decomp_last;
> +	struct decomp *decomp, *decomp_last = session->active_reader ?
> +		session->active_reader->decomp_last : session->decomp_last;
> +	struct zstd_data *zstd_data = session->active_reader ?
> +		&session->active_reader->zstd_data : &session->zstd_data;
>  
>  	if (decomp_last) {
>  		decomp_last_rem = decomp_last->size - decomp_last->head;
> @@ -109,7 +115,7 @@ static int perf_session__process_compressed_event(struct perf_session *session,
>  	src = (void *)event + sizeof(struct perf_record_compressed);
>  	src_size = event->pack.header.size - sizeof(struct perf_record_compressed);
>  
> -	decomp_size = zstd_decompress_stream(&(session->zstd_data), src, src_size,
> +	decomp_size = zstd_decompress_stream(zstd_data, src, src_size,
>  				&(decomp->data[decomp_last_rem]), decomp_len - decomp_last_rem);
>  	if (!decomp_size) {
>  		munmap(decomp, mmap_len);
> @@ -119,12 +125,22 @@ static int perf_session__process_compressed_event(struct perf_session *session,
>  
>  	decomp->size += decomp_size;
>  
> -	if (session->decomp == NULL) {
> -		session->decomp = decomp;
> -		session->decomp_last = decomp;
> +	if (session->active_reader) {
> +		if (session->active_reader->decomp == NULL) {
> +			session->active_reader->decomp = decomp;
> +			session->active_reader->decomp_last = decomp;
> +		} else {
> +			session->active_reader->decomp_last->next = decomp;
> +			session->active_reader->decomp_last = decomp;
> +		}
>  	} else {
> -		session->decomp_last->next = decomp;
> -		session->decomp_last = decomp;
> +		if (session->decomp == NULL) {
> +			session->decomp = decomp;
> +			session->decomp_last = decomp;
> +		} else {
> +			session->decomp_last->next = decomp;
> +			session->decomp_last = decomp;
> +		}
>  	}
>  
>  	pr_debug("decomp (B): %zd to %zd\n", src_size, decomp_size);
> @@ -314,11 +330,11 @@ static void perf_session__delete_threads(struct perf_session *session)
>  	machine__delete_threads(&session->machines.host);
>  }
>  
> -static void perf_session__release_decomp_events(struct perf_session *session)
> +static void perf_decomp__release_events(struct decomp *next)
>  {
> -	struct decomp *next, *decomp;
> +	struct decomp *decomp;
>  	size_t mmap_len;
> -	next = session->decomp;
> +
>  	do {
>  		decomp = next;
>  		if (decomp == NULL)
> @@ -337,7 +353,7 @@ void perf_session__delete(struct perf_session *session)
>  	auxtrace_index__free(&session->auxtrace_index);
>  	perf_session__destroy_kernel_maps(session);
>  	perf_session__delete_threads(session);
> -	perf_session__release_decomp_events(session);
> +	perf_decomp__release_events(session->decomp);
>  	perf_env__exit(&session->header.env);
>  	machines__exit(&session->machines);
>  	if (session->data) {
> @@ -2155,7 +2171,8 @@ static int __perf_session__process_decomp_events(struct perf_session *session)
>  {
>  	s64 skip;
>  	u64 size, file_pos = 0;
> -	struct decomp *decomp = session->decomp_last;
> +	struct decomp *decomp = session->active_reader ?
> +		session->active_reader->decomp_last : session->decomp_last;
>  
>  	if (!decomp)
>  		return 0;
> @@ -2212,6 +2229,9 @@ reader__process_events(struct reader *rd, struct perf_session *session,
>  
>  	memset(mmaps, 0, sizeof(st->mmaps));
>  
> +	if (zstd_init(&rd->zstd_data, 0))
> +		return -1;
> +
>  	mmap_prot  = PROT_READ;
>  	mmap_flags = MAP_SHARED;
>  
> @@ -2255,6 +2275,7 @@ reader__process_events(struct reader *rd, struct perf_session *session,
>  		goto remap;
>  	}
>  
> +	session->active_reader = rd;
>  	size = event->header.size;
>  
>  	skip = -EINVAL;
> @@ -2287,6 +2308,9 @@ reader__process_events(struct reader *rd, struct perf_session *session,
>  		goto more;
>  
>  out:
> +	session->active_reader = NULL;
> +	perf_decomp__release_events(rd->decomp);
> +	zstd_fini(&rd->zstd_data);
>  	return err;
>  }
>  
> diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
> index 5d8bd14a0a39..45f9f652a12a 100644
> --- a/tools/perf/util/session.h
> +++ b/tools/perf/util/session.h
> @@ -19,6 +19,7 @@ struct thread;
>  
>  struct auxtrace;
>  struct itrace_synth_opts;
> +struct reader;
>  
>  struct perf_session {
>  	struct perf_header	header;
> @@ -41,6 +42,7 @@ struct perf_session {
>  	struct zstd_data	zstd_data;
>  	struct decomp		*decomp;
>  	struct decomp		*decomp_last;
> +	struct reader           *active_reader;
>  };
>  
>  struct decomp {
> -- 
> 2.19.0
>