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Date:	Wed, 24 Dec 2014 11:45:04 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 37/37] perf data: Implement 'split' subcommand

Em Wed, Dec 24, 2014 at 11:14:47PM +0900, Namhyung Kim escreveu:
> Hi Arnaldo,
> 
> On Wed, Dec 24, 2014 at 10:51 PM, Arnaldo Carvalho de Melo
> <acme@...nel.org> wrote:
> > Em Wed, Dec 24, 2014 at 04:15:33PM +0900, Namhyung Kim escreveu:
> >> The perf data split command is for splitting a (large) single data
> >> file into multiple files under a directory (perf.data.dir by default)
> >> so that it can be processed and reported using multiple threads.
> >
> > How is it split? By CPU?
> > Will the metadata stay in a different file?
> > Please be as verbose on the description as possible :-)
> 
> It depends on the data file - if it's recorded system-wide, the split
> will be done by cpu, otherwise by thread.  It's determined by checking
> sample type has PERF_SAMPLE_CPU.  And metadata is saved in a separate
> perf.header file like other multi-file data.  Will add it to the
> change log.

Thanks for the explanation!

Please try to add such more detailed information on the change logs, as
the reviewing process starts at the idea/design, and that is first read
in the changelog, only after understanding what you want to do is that
we should bother looking if you did what you say you would do :-)

- Arnaldo
 
> Thanks,
> Namhyung
> 
> 
> >> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> >> ---
> >>  tools/perf/Documentation/perf-data.txt |  28 +++++
> >>  tools/perf/builtin-data.c              | 223 +++++++++++++++++++++++++++++++++
> >>  2 files changed, 251 insertions(+)
> >>
> >> diff --git a/tools/perf/Documentation/perf-data.txt b/tools/perf/Documentation/perf-data.txt
> >> index b8c83947715c..42708702f10c 100644
> >> --- a/tools/perf/Documentation/perf-data.txt
> >> +++ b/tools/perf/Documentation/perf-data.txt
> >> @@ -13,3 +13,31 @@ SYNOPSIS
> >>  DESCRIPTION
> >>  -----------
> >>  Data file related processing.
> >> +
> >> +COMMANDS
> >> +--------
> >> +split::
> >> +     Split single data file (perf.data) into multiple files under a directory
> >> +     in order to be reported by multiple threads.
> >> +
> >> +OPTIONS for 'split'
> >> +---------------------
> >> +-i::
> >> +--input::
> >> +     Specify input perf data file path.
> >> +
> >> +-o::
> >> +--output::
> >> +     Specify output perf data directory path.
> >> +
> >> +-v::
> >> +--verbose::
> >> +        Be more verbose (show counter open errors, etc).
> >> +
> >> +-f::
> >> +--force::
> >> +        Don't complain, do it.
> >> +
> >> +SEE ALSO
> >> +--------
> >> +linkperf:perf[1], linkperf:perf-report[1]
> >> diff --git a/tools/perf/builtin-data.c b/tools/perf/builtin-data.c
> >> index 1eee97d020fa..5f3173826850 100644
> >> --- a/tools/perf/builtin-data.c
> >> +++ b/tools/perf/builtin-data.c
> >> @@ -2,10 +2,14 @@
> >>  #include "builtin.h"
> >>  #include "perf.h"
> >>  #include "debug.h"
> >> +#include "session.h"
> >> +#include "evlist.h"
> >>  #include "parse-options.h"
> >>
> >>  typedef int (*data_cmd_fn_t)(int argc, const char **argv, const char *prefix);
> >>
> >> +static const char *output_name;
> >> +
> >>  struct data_cmd {
> >>       const char      *name;
> >>       const char      *summary;
> >> @@ -41,10 +45,229 @@ static void print_usage(void)
> >>       printf("\n");
> >>  }
> >>
> >> +static int data_cmd_split(int argc, const char **argv, const char *prefix);
> >> +
> >>  static struct data_cmd data_cmds[] = {
> >> +     { "split", "split single data file into multi-file", data_cmd_split },
> >>       { NULL },
> >>  };
> >>
> >> +#define FD_HASH_BITS  7
> >> +#define FD_HASH_SIZE  (1 << FD_HASH_BITS)
> >> +#define FD_HASH_MASK  (FD_HASH_SIZE - 1)
> >> +
> >> +struct data_split {
> >> +     struct perf_tool        tool;
> >> +     struct perf_session     *session;
> >> +     enum {
> >> +             PER_CPU,
> >> +             PER_THREAD,
> >> +     } mode;
> >> +     int                     header_fd;
> >> +     u64                     header_written;
> >> +     struct hlist_head       fd_hash[FD_HASH_SIZE];
> >> +     int                     fd_hash_nr;
> >> +};
> >> +
> >> +struct fdhash_node {
> >> +     int                     id;
> >> +     int                     fd;
> >> +     struct hlist_node       list;
> >> +};
> >> +
> >> +static struct hlist_head *get_hash(struct data_split *split, int id)
> >> +{
> >> +     return &split->fd_hash[id % FD_HASH_MASK];
> >> +}
> >> +
> >> +static int perf_event__rewrite_header(struct perf_tool *tool,
> >> +                                   union perf_event *event)
> >> +{
> >> +     struct data_split *split = container_of(tool, struct data_split, tool);
> >> +     ssize_t size;
> >> +
> >> +     size = writen(split->header_fd, event, event->header.size);
> >> +     if (size < 0)
> >> +             return -errno;
> >> +
> >> +     split->header_written += size;
> >> +     return 0;
> >> +}
> >> +
> >> +static int split_other_events(struct perf_tool *tool,
> >> +                             union perf_event *event,
> >> +                             struct perf_sample *sample __maybe_unused,
> >> +                             struct machine *machine __maybe_unused)
> >> +{
> >> +     return perf_event__rewrite_header(tool, event);
> >> +}
> >> +
> >> +static int split_sample_event(struct perf_tool *tool,
> >> +                             union perf_event *event,
> >> +                             struct perf_sample *sample,
> >> +                             struct perf_evsel *evsel __maybe_unused,
> >> +                             struct machine *machine __maybe_unused)
> >> +{
> >> +     struct data_split *split = container_of(tool, struct data_split, tool);
> >> +     int id = split->mode == PER_CPU ? sample->cpu : sample->tid;
> >> +     int fd = -1;
> >> +     char buf[PATH_MAX];
> >> +     struct hlist_head *head;
> >> +     struct fdhash_node *node;
> >> +
> >> +     head = get_hash(split, id);
> >> +     hlist_for_each_entry(node, head, list) {
> >> +             if (node->id == id) {
> >> +                     fd = node->fd;
> >> +                     break;
> >> +             }
> >> +     }
> >> +
> >> +     if (fd == -1) {
> >> +             scnprintf(buf, sizeof(buf), "%s/perf.data.%d",
> >> +                       output_name, split->fd_hash_nr++);
> >> +
> >> +             fd = open(buf, O_RDWR|O_CREAT|O_TRUNC, 0600);
> >> +             if (fd < 0) {
> >> +                     pr_err("cannot open data file: %s: %m\n", buf);
> >> +                     return -1;
> >> +             }
> >> +
> >> +             node = malloc(sizeof(*node));
> >> +             if (node == NULL) {
> >> +                     pr_err("memory allocation failed\n");
> >> +                     return -1;
> >> +             }
> >> +
> >> +             node->id = id;
> >> +             node->fd = fd;
> >> +
> >> +             hlist_add_head(&node->list, head);
> >> +     }
> >> +
> >> +     return writen(fd, event, event->header.size) > 0 ? 0 : -errno;
> >> +}
> >> +
> >> +static int __data_cmd_split(struct data_split *split)
> >> +{
> >> +     struct perf_session *session = split->session;
> >> +     char *output = NULL;
> >> +     char buf[PATH_MAX];
> >> +     u64 sample_type;
> >> +     int header_fd;
> >> +     int ret = -1;
> >> +     int i;
> >> +
> >> +     if (!output_name) {
> >> +             if (asprintf(&output, "%s.dir", input_name) < 0) {
> >> +                     pr_err("memory allocation failed\n");
> >> +                     return -1;
> >> +             }
> >> +             output_name = output;
> >> +     }
> >> +
> >> +     mkdir(output_name, 0700);
> >> +
> >> +     /*
> >> +      * This is necessary to write (copy) build-id table.  After
> >> +      * processing header, dsos list will contain dso which was on
> >> +      * the original build-id table.
> >> +      */
> >> +     dsos__hit_all(session);
> >> +
> >> +     scnprintf(buf, sizeof(buf), "%s/perf.header", output_name);
> >> +     header_fd = open(buf, O_RDWR|O_CREAT|O_TRUNC, 0600);
> >> +     if (header_fd < 0) {
> >> +             pr_err("cannot open header file: %s: %m\n", buf);
> >> +             goto out;
> >> +     }
> >> +
> >> +     lseek(header_fd, session->header.data_offset, SEEK_SET);
> >> +
> >> +     sample_type = perf_evlist__combined_sample_type(session->evlist);
> >> +     if (sample_type & PERF_SAMPLE_CPU)
> >> +             split->mode = PER_CPU;
> >> +     else
> >> +             split->mode = PER_THREAD;
> >> +
> >> +     pr_debug("splitting data file for %s\n",
> >> +              split->mode == PER_CPU ? "CPUs" : "threads");
> >> +
> >> +     split->header_fd = header_fd;
> >> +     perf_session__process_events(session, &split->tool);
> >> +
> >> +     for (i = 0; i < FD_HASH_SIZE; i++) {
> >> +             struct fdhash_node *pos;
> >> +             struct hlist_node *tmp;
> >> +
> >> +             hlist_for_each_entry_safe(pos, tmp, &split->fd_hash[i], list) {
> >> +                     hlist_del(&pos->list);
> >> +                     close(pos->fd);
> >> +                     free(pos);
> >> +             }
> >> +     }
> >> +
> >> +     session->header.data_size = split->header_written;
> >> +     perf_session__write_header(session, session->evlist, header_fd, true);
> >> +
> >> +     close(header_fd);
> >> +     ret = 0;
> >> +out:
> >> +     free(output);
> >> +     return ret;
> >> +}
> >> +
> >> +int data_cmd_split(int argc, const char **argv, const char *prefix __maybe_unused)
> >> +{
> >> +     bool force = false;
> >> +     struct perf_session *session;
> >> +     struct perf_data_file file = {
> >> +             .mode  = PERF_DATA_MODE_READ,
> >> +     };
> >> +     struct data_split split = {
> >> +             .tool = {
> >> +                     .sample         = split_sample_event,
> >> +                     .fork           = split_other_events,
> >> +                     .comm           = split_other_events,
> >> +                     .exit           = split_other_events,
> >> +                     .mmap           = split_other_events,
> >> +                     .mmap2          = split_other_events,
> >> +                     .lost           = split_other_events,
> >> +                     .throttle       = split_other_events,
> >> +                     .unthrottle     = split_other_events,
> >> +             },
> >> +     };
> >> +     const char * const split_usage[] = {
> >> +             "perf data split [<options>]",
> >> +             NULL
> >> +     };
> >> +     const struct option split_options[] = {
> >> +     OPT_STRING('i', "input", &input_name, "file", "input file name"),
> >> +     OPT_STRING('o', "output", &output_name, "file", "output directory name"),
> >> +     OPT_BOOLEAN('f', "force", &force, "don't complain, do it"),
> >> +     OPT_INCR('v', "verbose", &verbose, "be more verbose"),
> >> +     OPT_END()
> >> +     };
> >> +
> >> +     argc = parse_options(argc, argv, split_options, split_usage, 0);
> >> +     if (argc)
> >> +             usage_with_options(split_usage, split_options);
> >> +
> >> +     file.path = input_name;
> >> +     file.force = force;
> >> +     session = perf_session__new(&file, false, &split.tool);
> >> +     if (session == NULL)
> >> +             return -1;
> >> +
> >> +     split.session = session;
> >> +     symbol__init(&session->header.env);
> >> +
> >> +     __data_cmd_split(&split);
> >> +
> >> +     perf_session__delete(session);
> >> +     return 0;
> >> +}
> >> +
> >>  int cmd_data(int argc, const char **argv, const char *prefix)
> >>  {
> >>       struct data_cmd *cmd;
> >> --
> >> 2.1.3
> 
> 
> 
> -- 
> Thanks,
> Namhyung
--
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