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Message-ID: <CAM9d7cgehgF0pXm_7VME0jUo=8dHwRH7_EruGqP7D-CVaj5sEw@mail.gmail.com>
Date: Wed, 18 Oct 2023 16:21:35 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Nick Terrell <terrelln@...com>,
Kan Liang <kan.liang@...ux.intel.com>,
Song Liu <song@...nel.org>,
Sandipan Das <sandipan.das@....com>,
Anshuman Khandual <anshuman.khandual@....com>,
James Clark <james.clark@....com>,
Liam Howlett <liam.howlett@...cle.com>,
Miguel Ojeda <ojeda@...nel.org>, Leo Yan <leo.yan@...aro.org>,
German Gomez <german.gomez@....com>,
Ravi Bangoria <ravi.bangoria@....com>,
Artem Savkov <asavkov@...hat.com>,
Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
Andi Kleen <ak@...ux.intel.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH v2 12/13] perf mmap: Lazily initialize zstd streams
On Wed, Oct 11, 2023 at 11:24 PM Ian Rogers <irogers@...gle.com> wrote:
>
> Zstd streams create dictionaries that can require significant RAM,
> especially when there is one per-CPU. Tools like perf record won't use
> the streams without the -z option, and so the creation of the streams
> is pure overhead. Switch to creating the streams on first use.
>
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
> tools/perf/util/compress.h | 1 +
> tools/perf/util/mmap.c | 5 ++--
> tools/perf/util/mmap.h | 1 -
> tools/perf/util/zstd.c | 61 ++++++++++++++++++++------------------
> 4 files changed, 35 insertions(+), 33 deletions(-)
>
> diff --git a/tools/perf/util/compress.h b/tools/perf/util/compress.h
> index 0cd3369af2a4..9391850f1a7e 100644
> --- a/tools/perf/util/compress.h
> +++ b/tools/perf/util/compress.h
> @@ -21,6 +21,7 @@ struct zstd_data {
> #ifdef HAVE_ZSTD_SUPPORT
> ZSTD_CStream *cstream;
> ZSTD_DStream *dstream;
> + int comp_level;
> #endif
> };
>
> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> index 49093b21ee2d..122ee198a86e 100644
> --- a/tools/perf/util/mmap.c
> +++ b/tools/perf/util/mmap.c
> @@ -295,15 +295,14 @@ int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, struct perf_cpu
>
> map->core.flush = mp->flush;
>
> - map->comp_level = mp->comp_level;
> #ifndef PYTHON_PERF
> - if (zstd_init(&map->zstd_data, map->comp_level)) {
> + if (zstd_init(&map->zstd_data, mp->comp_level)) {
> pr_debug2("failed to init mmap compressor, error %d\n", errno);
> return -1;
> }
> #endif
>
> - if (map->comp_level && !perf_mmap__aio_enabled(map)) {
> + if (mp->comp_level && !perf_mmap__aio_enabled(map)) {
> map->data = mmap(NULL, mmap__mmap_len(map), PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
> if (map->data == MAP_FAILED) {
> diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
> index f944c3cd5efa..0df6e1621c7e 100644
> --- a/tools/perf/util/mmap.h
> +++ b/tools/perf/util/mmap.h
> @@ -39,7 +39,6 @@ struct mmap {
> #endif
> struct mmap_cpu_mask affinity_mask;
> void *data;
> - int comp_level;
> struct perf_data_file *file;
> struct zstd_data zstd_data;
> };
> diff --git a/tools/perf/util/zstd.c b/tools/perf/util/zstd.c
> index 48dd2b018c47..60f2d749b1c0 100644
> --- a/tools/perf/util/zstd.c
> +++ b/tools/perf/util/zstd.c
> @@ -7,35 +7,9 @@
>
> int zstd_init(struct zstd_data *data, int level)
> {
> - size_t ret;
> -
> - data->dstream = ZSTD_createDStream();
> - if (data->dstream == NULL) {
> - pr_err("Couldn't create decompression stream.\n");
> - return -1;
> - }
> -
> - ret = ZSTD_initDStream(data->dstream);
> - if (ZSTD_isError(ret)) {
> - pr_err("Failed to initialize decompression stream: %s\n", ZSTD_getErrorName(ret));
> - return -1;
> - }
> -
> - if (!level)
> - return 0;
> -
> - data->cstream = ZSTD_createCStream();
> - if (data->cstream == NULL) {
> - pr_err("Couldn't create compression stream.\n");
> - return -1;
> - }
> -
> - ret = ZSTD_initCStream(data->cstream, level);
> - if (ZSTD_isError(ret)) {
> - pr_err("Failed to initialize compression stream: %s\n", ZSTD_getErrorName(ret));
> - return -1;
> - }
> -
> + data->comp_level = level;
> + data->dstream = NULL;
> + data->cstream = NULL;
> return 0;
> }
>
> @@ -63,6 +37,21 @@ size_t zstd_compress_stream_to_records(struct zstd_data *data, void *dst, size_t
> ZSTD_outBuffer output;
> void *record;
>
> + if (!data->cstream) {
> + data->cstream = ZSTD_createCStream();
> + if (data->cstream == NULL) {
> + pr_err("Couldn't create compression stream.\n");
> + return -1;
> + }
> +
> + ret = ZSTD_initCStream(data->cstream, data->comp_level);
> + if (ZSTD_isError(ret)) {
> + pr_err("Failed to initialize compression stream: %s\n",
> + ZSTD_getErrorName(ret));
> + return -1;
I'm not sure if the callers are ready to handle the failure.
Thanks,
Namhyung
> + }
> + }
> +
> while (input.pos < input.size) {
> record = dst;
> size = process_header(record, 0);
> @@ -96,6 +85,20 @@ size_t zstd_decompress_stream(struct zstd_data *data, void *src, size_t src_size
> ZSTD_inBuffer input = { src, src_size, 0 };
> ZSTD_outBuffer output = { dst, dst_size, 0 };
>
> + if (!data->dstream) {
> + data->dstream = ZSTD_createDStream();
> + if (data->dstream == NULL) {
> + pr_err("Couldn't create decompression stream.\n");
> + return -1;
> + }
> +
> + ret = ZSTD_initDStream(data->dstream);
> + if (ZSTD_isError(ret)) {
> + pr_err("Failed to initialize decompression stream: %s\n",
> + ZSTD_getErrorName(ret));
> + return -1;
> + }
> + }
> while (input.pos < input.size) {
> ret = ZSTD_decompressStream(data->dstream, &output, &input);
> if (ZSTD_isError(ret)) {
> --
> 2.42.0.609.gbb76f46606-goog
>
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