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Date: Tue, 24 Oct 2023 12:21:23 -0700
From: Ian Rogers <irogers@...gle.com>
To: Namhyung Kim <namhyung@...nel.org>
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 18, 2023 at 4:21 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> 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, fixed in v3.
Ian
> 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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