Ping. Thanks, Teresa
On Fri, Dec 14, 2012 at 6:11 PM, Teresa Johnson <tejohn...@google.com> wrote:
> This patch enables the gcov-dump tool to optionally compute and dump
> the working set information from the counter histogram, via a new -w option.
> This is useful to help understand and tune how the compiler will use
> the counter histogram, since it first computes the working set and selects
> thresholds based on that.
>
> This required moving the bulk of the compute_working_sets functionality
> into gcov-io.c so that it was accessible by gcov-dump.c.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, and tested with various
> gcda files. Ok for trunk?
>
> 2012-12-14 Teresa Johnson <tejohn...@google.com>
>
> * lto-cgraph.c (input_symtab): Replace call to compute_working_sets
> to get_working_sets.
> * gcov-io.c (compute_working_sets): Moved most of body of old
> compute_working_sets here from profile.c.
> * gcov-io.h (NUM_GCOV_WORKING_SETS): Moved here from profile.c.
> (gcov_working_set_t): Moved typedef here from basic-block.h
> (compute_working_set): Declare.
> * profile.c (NUM_GCOV_WORKING_SETS): Moved to gcov-io.h.
> (get_working_sets): Renamed from compute_working_set,
> replace most of body with call to new compute_working_sets.
> (get_exec_counts): Replace call to compute_working_sets
> to get_working_sets.
> * profile.h (get_working_sets): Renamed from
> compute_working_set.
> * basic-block.h (gcov_working_set_t): Moved to gcov-io.h.
> * gcov-dump.c (dump_working_sets): New function.
>
> Index: lto-cgraph.c
> ===================================================================
> --- lto-cgraph.c (revision 194502)
> +++ lto-cgraph.c (working copy)
> @@ -1457,7 +1457,7 @@ input_symtab (void)
> }
>
> merge_profile_summaries (file_data_vec);
> - compute_working_sets ();
> + get_working_sets ();
>
>
> /* Clear out the aux field that was used to store enough state to
> Index: gcov-io.c
> ===================================================================
> --- gcov-io.c (revision 194502)
> +++ gcov-io.c (working copy)
> @@ -806,3 +806,110 @@ static void gcov_histogram_merge (gcov_bucket_type
> memcpy(tgt_histo, tmp_histo, sizeof (gcov_bucket_type) *
> GCOV_HISTOGRAM_SIZE);
> }
> #endif /* !IN_GCOV */
> +
> +/* This is used by gcov-dump (IN_GCOV == -1) and in the compiler
> + (!IN_GCOV && !IN_LIBGCOV). */
> +#if IN_GCOV <= 0 && !IN_LIBGCOV
> +/* Compute the working set information from the counter histogram in
> + the profile summary. This is an array of information corresponding to a
> + range of percentages of the total execution count (sum_all), and includes
> + the number of counters required to cover that working set percentage and
> + the minimum counter value in that working set. */
> +
> +GCOV_LINKAGE void
> +compute_working_sets (const struct gcov_ctr_summary *summary,
> + gcov_working_set_t *gcov_working_sets)
> +{
> + gcov_type working_set_cum_values[NUM_GCOV_WORKING_SETS];
> + gcov_type ws_cum_hotness_incr;
> + gcov_type cum, tmp_cum;
> + const gcov_bucket_type *histo_bucket;
> + unsigned ws_ix, c_num, count;
> + int h_ix;
> +
> + /* Compute the amount of sum_all that the cumulative hotness grows
> + by in each successive working set entry, which depends on the
> + number of working set entries. */
> + ws_cum_hotness_incr = summary->sum_all / NUM_GCOV_WORKING_SETS;
> +
> + /* Next fill in an array of the cumulative hotness values corresponding
> + to each working set summary entry we are going to compute below.
> + Skip 0% statistics, which can be extrapolated from the
> + rest of the summary data. */
> + cum = ws_cum_hotness_incr;
> + for (ws_ix = 0; ws_ix < NUM_GCOV_WORKING_SETS;
> + ws_ix++, cum += ws_cum_hotness_incr)
> + working_set_cum_values[ws_ix] = cum;
> + /* The last summary entry is reserved for (roughly) 99.9% of the
> + working set. Divide by 1024 so it becomes a shift, which gives
> + almost exactly 99.9%. */
> + working_set_cum_values[NUM_GCOV_WORKING_SETS-1]
> + = summary->sum_all - summary->sum_all/1024;
> +
> + /* Next, walk through the histogram in decending order of hotness
> + and compute the statistics for the working set summary array.
> + As histogram entries are accumulated, we check to see which
> + working set entries have had their expected cum_value reached
> + and fill them in, walking the working set entries in increasing
> + size of cum_value. */
> + ws_ix = 0; /* The current entry into the working set array. */
> + cum = 0; /* The current accumulated counter sum. */
> + count = 0; /* The current accumulated count of block counters. */
> + for (h_ix = GCOV_HISTOGRAM_SIZE - 1;
> + h_ix >= 0 && ws_ix < NUM_GCOV_WORKING_SETS; h_ix--)
> + {
> + histo_bucket = &summary->histogram[h_ix];
> +
> + /* If we haven't reached the required cumulative counter value for
> + the current working set percentage, simply accumulate this histogram
> + entry into the running sums and continue to the next histogram
> + entry. */
> + if (cum + histo_bucket->cum_value < working_set_cum_values[ws_ix])
> + {
> + cum += histo_bucket->cum_value;
> + count += histo_bucket->num_counters;
> + continue;
> + }
> +
> + /* If adding the current histogram entry's cumulative counter value
> + causes us to exceed the current working set size, then estimate
> + how many of this histogram entry's counter values are required to
> + reach the working set size, and fill in working set entries
> + as we reach their expected cumulative value. */
> + for (c_num = 0, tmp_cum = cum;
> + c_num < histo_bucket->num_counters && ws_ix <
> NUM_GCOV_WORKING_SETS;
> + c_num++)
> + {
> + count++;
> + /* If we haven't reached the last histogram entry counter, add
> + in the minimum value again. This will underestimate the
> + cumulative sum so far, because many of the counter values in
> this
> + entry may have been larger than the minimum. We could add in the
> + average value every time, but that would require an expensive
> + divide operation. */
> + if (c_num + 1 < histo_bucket->num_counters)
> + tmp_cum += histo_bucket->min_value;
> + /* If we have reached the last histogram entry counter, then add
> + in the entire cumulative value. */
> + else
> + tmp_cum = cum + histo_bucket->cum_value;
> +
> + /* Next walk through successive working set entries and fill in
> + the statistics for any whose size we have reached by accumulating
> + this histogram counter. */
> + while (ws_ix < NUM_GCOV_WORKING_SETS
> + && tmp_cum >= working_set_cum_values[ws_ix])
> + {
> + gcov_working_sets[ws_ix].num_counters = count;
> + gcov_working_sets[ws_ix].min_counter
> + = histo_bucket->min_value;
> + ws_ix++;
> + }
> + }
> + /* Finally, update the running cumulative value since we were
> + using a temporary above. */
> + cum += histo_bucket->cum_value;
> + }
> + gcc_assert (ws_ix == NUM_GCOV_WORKING_SETS);
> +}
> +#endif /* IN_GCOV <= 0 && !IN_LIBGCOV */
> Index: gcov-io.h
> ===================================================================
> --- gcov-io.h (revision 194502)
> +++ gcov-io.h (working copy)
> @@ -618,6 +618,28 @@ GCOV_LINKAGE gcov_position_t gcov_write_tag (gcov_
> GCOV_LINKAGE void gcov_write_length (gcov_position_t /*position*/);
> #endif
>
> +#if IN_GCOV <= 0 && !IN_LIBGCOV
> +/* Available in gcov-dump and the compiler. */
> +
> +/* Number of data points in the working set summary array. Using 128
> + provides information for at least every 1% increment of the total
> + profile size. The last entry is hardwired to 99.9% of the total. */
> +#define NUM_GCOV_WORKING_SETS 128
> +
> +/* Working set size statistics for a given percentage of the entire
> + profile (sum_all from the counter summary). */
> +typedef struct gcov_working_set_info
> +{
> + /* Number of hot counters included in this working set. */
> + unsigned num_counters;
> + /* Smallest counter included in this working set. */
> + gcov_type min_counter;
> +} gcov_working_set_t;
> +
> +GCOV_LINKAGE void compute_working_sets (const struct gcov_ctr_summary
> *summary,
> + gcov_working_set_t
> *gcov_working_sets);
> +#endif
> +
> #if IN_GCOV > 0
> /* Available in gcov */
> GCOV_LINKAGE time_t gcov_time (void);
> Index: profile.c
> ===================================================================
> --- profile.c (revision 194502)
> +++ profile.c (working copy)
> @@ -84,11 +84,6 @@ struct bb_info {
>
> const struct gcov_ctr_summary *profile_info;
>
> -/* Number of data points in the working set summary array. Using 128
> - provides information for at least every 1% increment of the total
> - profile size. The last entry is hardwired to 99.9% of the total. */
> -#define NUM_GCOV_WORKING_SETS 128
> -
> /* Counter working set information computed from the current counter
> summary. Not initialized unless profile_info summary is non-NULL. */
> static gcov_working_set_t gcov_working_sets[NUM_GCOV_WORKING_SETS];
> @@ -208,104 +203,16 @@ instrument_values (histogram_values values)
> the minimum counter value in that working set. */
>
> void
> -compute_working_sets (void)
> +get_working_sets (void)
> {
> - gcov_type working_set_cum_values[NUM_GCOV_WORKING_SETS];
> - gcov_type ws_cum_hotness_incr;
> - gcov_type cum, tmp_cum;
> - const gcov_bucket_type *histo_bucket;
> - unsigned ws_ix, c_num, count, pctinc, pct;
> - int h_ix;
> + unsigned ws_ix, pctinc, pct;
> gcov_working_set_t *ws_info;
>
> if (!profile_info)
> return;
>
> - /* Compute the amount of sum_all that the cumulative hotness grows
> - by in each successive working set entry, which depends on the
> - number of working set entries. */
> - ws_cum_hotness_incr = profile_info->sum_all / NUM_GCOV_WORKING_SETS;
> + compute_working_sets (profile_info, gcov_working_sets);
>
> - /* Next fill in an array of the cumulative hotness values corresponding
> - to each working set summary entry we are going to compute below.
> - Skip 0% statistics, which can be extrapolated from the
> - rest of the summary data. */
> - cum = ws_cum_hotness_incr;
> - for (ws_ix = 0; ws_ix < NUM_GCOV_WORKING_SETS;
> - ws_ix++, cum += ws_cum_hotness_incr)
> - working_set_cum_values[ws_ix] = cum;
> - /* The last summary entry is reserved for (roughly) 99.9% of the
> - working set. Divide by 1024 so it becomes a shift, which gives
> - almost exactly 99.9%. */
> - working_set_cum_values[NUM_GCOV_WORKING_SETS-1]
> - = profile_info->sum_all - profile_info->sum_all/1024;
> -
> - /* Next, walk through the histogram in decending order of hotness
> - and compute the statistics for the working set summary array.
> - As histogram entries are accumulated, we check to see which
> - working set entries have had their expected cum_value reached
> - and fill them in, walking the working set entries in increasing
> - size of cum_value. */
> - ws_ix = 0; /* The current entry into the working set array. */
> - cum = 0; /* The current accumulated counter sum. */
> - count = 0; /* The current accumulated count of block counters. */
> - for (h_ix = GCOV_HISTOGRAM_SIZE - 1;
> - h_ix >= 0 && ws_ix < NUM_GCOV_WORKING_SETS; h_ix--)
> - {
> - histo_bucket = &profile_info->histogram[h_ix];
> -
> - /* If we haven't reached the required cumulative counter value for
> - the current working set percentage, simply accumulate this histogram
> - entry into the running sums and continue to the next histogram
> - entry. */
> - if (cum + histo_bucket->cum_value < working_set_cum_values[ws_ix])
> - {
> - cum += histo_bucket->cum_value;
> - count += histo_bucket->num_counters;
> - continue;
> - }
> -
> - /* If adding the current histogram entry's cumulative counter value
> - causes us to exceed the current working set size, then estimate
> - how many of this histogram entry's counter values are required to
> - reach the working set size, and fill in working set entries
> - as we reach their expected cumulative value. */
> - for (c_num = 0, tmp_cum = cum;
> - c_num < histo_bucket->num_counters && ws_ix <
> NUM_GCOV_WORKING_SETS;
> - c_num++)
> - {
> - count++;
> - /* If we haven't reached the last histogram entry counter, add
> - in the minimum value again. This will underestimate the
> - cumulative sum so far, because many of the counter values in
> this
> - entry may have been larger than the minimum. We could add in the
> - average value every time, but that would require an expensive
> - divide operation. */
> - if (c_num + 1 < histo_bucket->num_counters)
> - tmp_cum += histo_bucket->min_value;
> - /* If we have reached the last histogram entry counter, then add
> - in the entire cumulative value. */
> - else
> - tmp_cum = cum + histo_bucket->cum_value;
> -
> - /* Next walk through successive working set entries and fill in
> - the statistics for any whose size we have reached by accumulating
> - this histogram counter. */
> - while (ws_ix < NUM_GCOV_WORKING_SETS
> - && tmp_cum >= working_set_cum_values[ws_ix])
> - {
> - gcov_working_sets[ws_ix].num_counters = count;
> - gcov_working_sets[ws_ix].min_counter
> - = histo_bucket->min_value;
> - ws_ix++;
> - }
> - }
> - /* Finally, update the running cumulative value since we were
> - using a temporary above. */
> - cum += histo_bucket->cum_value;
> - }
> - gcc_assert (ws_ix == NUM_GCOV_WORKING_SETS);
> -
> if (dump_file)
> {
> fprintf (dump_file, "Counter working sets:\n");
> @@ -374,7 +281,7 @@ get_exec_counts (unsigned cfg_checksum, unsigned l
> if (!counts)
> return NULL;
>
> - compute_working_sets();
> + get_working_sets();
>
> if (dump_file && profile_info)
> fprintf(dump_file, "Merged %u profiles with maximal count %u.\n",
> Index: profile.h
> ===================================================================
> --- profile.h (revision 194502)
> +++ profile.h (working copy)
> @@ -47,6 +47,6 @@ extern gcov_type sum_edge_counts (vec<edge, va_gc>
> extern void init_node_map (void);
> extern void del_node_map (void);
>
> -extern void compute_working_sets (void);
> +extern void get_working_sets (void);
>
> #endif /* PROFILE_H */
> Index: basic-block.h
> ===================================================================
> --- basic-block.h (revision 194502)
> +++ basic-block.h (working copy)
> @@ -88,16 +88,6 @@ enum cfg_edge_flags {
> profile.c. */
> extern const struct gcov_ctr_summary *profile_info;
>
> -/* Working set size statistics for a given percentage of the entire
> - profile (sum_all from the counter summary). */
> -typedef struct gcov_working_set_info
> -{
> - /* Number of hot counters included in this working set. */
> - unsigned num_counters;
> - /* Smallest counter included in this working set. */
> - gcov_type min_counter;
> -} gcov_working_set_t;
> -
> /* Structure to gather statistic about profile consistency, per pass.
> An array of this structure, indexed by pass static number, is allocated
> in passes.c. The structure is defined here so that different CFG modes
> @@ -934,6 +924,7 @@ extern void rtl_profile_for_edge (edge);
> extern void default_rtl_profile (void);
>
> /* In profile.c. */
> +typedef struct gcov_working_set_info gcov_working_set_t;
> extern gcov_working_set_t *find_working_set(unsigned pct_times_10);
>
> /* Check tha probability is sane. */
> Index: gcov-dump.c
> ===================================================================
> --- gcov-dump.c (revision 194502)
> +++ gcov-dump.c (working copy)
> @@ -39,6 +39,8 @@ static void tag_arcs (const char *, unsigned, unsi
> static void tag_lines (const char *, unsigned, unsigned);
> static void tag_counters (const char *, unsigned, unsigned);
> static void tag_summary (const char *, unsigned, unsigned);
> +static void dump_working_sets (const char *filename ATTRIBUTE_UNUSED,
> + const struct gcov_ctr_summary *summary);
> extern int main (int, char **);
>
> typedef struct tag_format
> @@ -50,6 +52,7 @@ typedef struct tag_format
>
> static int flag_dump_contents = 0;
> static int flag_dump_positions = 0;
> +static int flag_dump_working_sets = 0;
>
> static const struct option options[] =
> {
> @@ -57,6 +60,7 @@ static const struct option options[] =
> { "version", no_argument, NULL, 'v' },
> { "long", no_argument, NULL, 'l' },
> { "positions", no_argument, NULL, 'o' },
> + { "working-sets", no_argument, NULL, 'w' },
> { 0, 0, 0, 0 }
> };
>
> @@ -94,7 +98,7 @@ main (int argc ATTRIBUTE_UNUSED, char **argv)
>
> diagnostic_initialize (global_dc, 0);
>
> - while ((opt = getopt_long (argc, argv, "hlpv", options, NULL)) != -1)
> + while ((opt = getopt_long (argc, argv, "hlpvw", options, NULL)) != -1)
> {
> switch (opt)
> {
> @@ -110,6 +114,9 @@ main (int argc ATTRIBUTE_UNUSED, char **argv)
> case 'p':
> flag_dump_positions = 1;
> break;
> + case 'w':
> + flag_dump_working_sets = 1;
> + break;
> default:
> fprintf (stderr, "unknown flag `%c'\n", opt);
> }
> @@ -129,6 +136,7 @@ print_usage (void)
> printf (" -v, --version Print version number\n");
> printf (" -l, --long Dump record contents too\n");
> printf (" -p, --positions Dump record positions\n");
> + printf (" -w, --working-sets Dump working set computed from summary\n");
> }
>
> static void
> @@ -485,5 +493,39 @@ tag_summary (const char *filename ATTRIBUTE_UNUSED
> (HOST_WIDEST_INT)histo_bucket->min_value,
> (HOST_WIDEST_INT)histo_bucket->cum_value);
> }
> + if (flag_dump_working_sets)
> + dump_working_sets (filename, &summary.ctrs[ix]);
> }
> }
> +
> +static void
> +dump_working_sets (const char *filename ATTRIBUTE_UNUSED,
> + const struct gcov_ctr_summary *summary)
> +{
> + gcov_working_set_t gcov_working_sets[NUM_GCOV_WORKING_SETS];
> + unsigned ws_ix, pctinc, pct;
> + gcov_working_set_t *ws_info;
> +
> + compute_working_sets (summary, gcov_working_sets);
> +
> + printf ("\n");
> + print_prefix (filename, 0, 0);
> + printf ("\t\tcounter working sets:");
> + /* Multiply the percentage by 100 to avoid float. */
> + pctinc = 100 * 100 / NUM_GCOV_WORKING_SETS;
> + for (ws_ix = 0, pct = pctinc; ws_ix < NUM_GCOV_WORKING_SETS;
> + ws_ix++, pct += pctinc)
> + {
> + if (ws_ix == NUM_GCOV_WORKING_SETS - 1)
> + pct = 9990;
> + ws_info = &gcov_working_sets[ws_ix];
> + /* Print out the percentage using int arithmatic to avoid float. */
> + printf ("\n");
> + print_prefix (filename, 0, 0);
> + printf ("\t\t%u.%02u%%: num counts=%u, min counter="
> + HOST_WIDEST_INT_PRINT_DEC,
> + pct / 100, pct - (pct / 100 * 100),
> + ws_info->num_counters,
> + (HOST_WIDEST_INT)ws_info->min_counter);
> + }
> +}
>
> --
> This patch is available for review at http://codereview.appspot.com/6940061
--
Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
