Re: [PATCH 4/5] sparse-index: count lstat() calls

>
> From: Derrick Stolee <stolee@gmail.com>
>
> The clear_skip_worktree.. methods already report some statistics about
> how many cache entries are checked against path_found() due to having
> the skip-worktree bit set. However, due to path_found() performing some
> caching, this isn't the only information that would be helpful to
> report.
>
> Add a new lstat_count member to the path_found_data struct to count the
> number of times path_found() calls lstat(). This will be helpful to help
> explain performance problems in this method as well as to demonstrate
> future changes to the caching algorithm in a more concrete way than
> end-to-end timings.
>
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---
>  sparse-index.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/sparse-index.c b/sparse-index.c
> index fec4f393360..8577fa726b8 100644
> --- a/sparse-index.c
> +++ b/sparse-index.c
> @@ -442,6 +442,7 @@ void ensure_correct_sparsity(struct index_state *istate)
>  struct path_found_data {
>         struct strbuf dir;
>         int dir_found;
> +       size_t lstat_count;
>  };
>
>  #define PATH_FOUND_DATA_INIT { \
> @@ -469,6 +470,7 @@ static int path_found(const char *path, struct path_found_data *data)
>         /*
>          * If path itself exists, return 1.
>          */
> +       data->lstat_count++;
>         if (!lstat(path, &st))
>                 return 1;
>
> @@ -493,6 +495,7 @@ static int path_found(const char *path, struct path_found_data *data)
>         strbuf_reset(&data->dir);
>         strbuf_add(&data->dir, path, newdir - path + 1);
>
> +       data->lstat_count++;
>         data->dir_found = !lstat(data->dir.buf, &st);
>
>         return 0;
> @@ -524,6 +527,8 @@ static int clear_skip_worktree_from_present_files_sparse(struct index_state *ist
>
>         trace2_data_intmax("index", istate->repo,
>                            "sparse_path_count", path_count);
> +       trace2_data_intmax("index", istate->repo,
> +                          "sparse_lstat_count", data.lstat_count);
>         trace2_region_leave("index", "clear_skip_worktree_from_present_files_sparse",
>                             istate->repo);
>         clear_path_found_data(&data);
> @@ -553,6 +558,8 @@ static void clear_skip_worktree_from_present_files_full(struct index_state *ista
>
>         trace2_data_intmax("index", istate->repo,
>                            "full_path_count", path_count);
> +       trace2_data_intmax("index", istate->repo,
> +                          "full_lstat_count", data.lstat_count);
>         trace2_region_leave("index", "clear_skip_worktree_from_present_files_full",
>                             istate->repo);
>         clear_path_found_data(&data);
> --
> gitgitgadget