On Thu, Oct 22, 2015 at 04:23:56PM +0300, Victor Leschuk wrote:
> Hello all, I suggest we make number of git-grep worker threads a configuration
> parameter. I have run several tests on systems with different number of CPU cores.
> It appeared that the hard-coded number 8 lowers performance on both of my systems:
> on my 4-core and 8-core systems the thread number of 4 worked about 20% faster than
> default 8. So I think it is better to allow users tune this parameter.
For git-pack-objects we call the command-line parameter "--threads" and
the config variable "pack.threads". Is there a reason not to use the
same name here (i.e. "--threads" and "grep.threads")?
> Signed-off-by: Victor Leschuk <vleschuk@xxxxxxxxxxxxxxxx>
> ---
> Documentation/config.txt | 4 ++++
> Documentation/git-grep.txt | 5 +++++
> builtin/grep.c | 20 +++++++++++++-------
> contrib/completion/git-completion.bash | 1 +
> grep.c | 15 +++++++++++++++
> grep.h | 4 ++++
> 6 files changed, 42 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index 391a0c3..c3df20c 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -1447,6 +1447,10 @@ grep.extendedRegexp::
> option is ignored when the 'grep.patternType' option is set to a value
> other than 'default'.
>
> +grep.threadsNum::
> + Number of grep worker threads, use it to tune up performance on
> + multicore machines. Default value is 8.
> +
> gpg.program::
> Use this custom program instead of "gpg" found on $PATH when
> making or verifying a PGP signature. The program must support the
> diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
> index 4a44d6d..e9ca265 100644
> --- a/Documentation/git-grep.txt
> +++ b/Documentation/git-grep.txt
> @@ -22,6 +22,7 @@ SYNOPSIS
> [--color[=<when>] | --no-color]
> [--break] [--heading] [-p | --show-function]
> [-A <post-context>] [-B <pre-context>] [-C <context>]
> + [-t <threads-num>]
> [-W | --function-context]
> [-f <file>] [-e] <pattern>
> [--and|--or|--not|(|)|-e <pattern>...]
> @@ -220,6 +221,10 @@ OPTIONS
> Show <num> leading lines, and place a line containing
> `--` between contiguous groups of matches.
>
> +-t <num>::
> +--threads-num <num>::
> + Set number of worker threads to <num>. Default is 8.
> +
> -W::
> --function-context::
> Show the surrounding text from the previous line containing a
> diff --git a/builtin/grep.c b/builtin/grep.c
> index d04f440..9b4fc47 100644
> --- a/builtin/grep.c
> +++ b/builtin/grep.c
> @@ -27,8 +27,7 @@ static char const * const grep_usage[] = {
> static int use_threads = 1;
>
> #ifndef NO_PTHREADS
> -#define THREADS 8
> -static pthread_t threads[THREADS];
> +static pthread_t *threads;
>
> /* We use one producer thread and THREADS consumer
> * threads. The producer adds struct work_items to 'todo' and the
> @@ -206,7 +205,8 @@ static void start_threads(struct grep_opt *opt)
> strbuf_init(&todo[i].out, 0);
> }
>
> - for (i = 0; i < ARRAY_SIZE(threads); i++) {
> + threads = xmalloc(sizeof(pthread_t) * opt->num_threads);
> + for (i = 0; i < opt->num_threads; i++) {
> int err;
> struct grep_opt *o = grep_opt_dup(opt);
> o->output = strbuf_out;
> @@ -220,7 +220,7 @@ static void start_threads(struct grep_opt *opt)
> }
> }
>
> -static int wait_all(void)
> +static int wait_all(struct grep_opt *opt)
> {
> int hit = 0;
> int i;
> @@ -238,12 +238,14 @@ static int wait_all(void)
> pthread_cond_broadcast(&cond_add);
> grep_unlock();
>
> - for (i = 0; i < ARRAY_SIZE(threads); i++) {
> + for (i = 0; i < opt->num_threads; i++) {
> void *h;
> pthread_join(threads[i], &h);
> hit |= (int) (intptr_t) h;
> }
>
> + free(threads);
> +
> pthread_mutex_destroy(&grep_mutex);
> pthread_mutex_destroy(&grep_read_mutex);
> pthread_mutex_destroy(&grep_attr_mutex);
> @@ -256,7 +258,7 @@ static int wait_all(void)
> }
> #else /* !NO_PTHREADS */
>
> -static int wait_all(void)
> +static int wait_all(struct grep_opt *opt)
> {
> return 0;
> }
> @@ -702,6 +704,10 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
> N_("show <n> context lines before matches")),
> OPT_INTEGER('A', "after-context", &opt.post_context,
> N_("show <n> context lines after matches")),
> +#ifndef NO_PTHREADS
> + OPT_INTEGER('t', "threads-num", &opt.num_threads,
> + N_("use <n> worker threads")),
> +#endif /* !NO_PTHREADS */
> OPT_NUMBER_CALLBACK(&opt, N_("shortcut for -C NUM"),
> context_callback),
> OPT_BOOL('p', "show-function", &opt.funcname,
> @@ -910,7 +916,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
> }
>
> if (use_threads)
> - hit |= wait_all();
> + hit |= wait_all(&opt);
> if (hit && show_in_pager)
> run_pager(&opt, prefix);
> free_grep_patterns(&opt);
> diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
> index 482ca84..6231595 100644
> --- a/contrib/completion/git-completion.bash
> +++ b/contrib/completion/git-completion.bash
> @@ -1310,6 +1310,7 @@ _git_grep ()
> --full-name --line-number
> --extended-regexp --basic-regexp --fixed-strings
> --perl-regexp
> + --threads-num
> --files-with-matches --name-only
> --files-without-match
> --max-depth
> diff --git a/grep.c b/grep.c
> index 7b2b96a..17e6a7c 100644
> --- a/grep.c
> +++ b/grep.c
> @@ -40,6 +40,9 @@ void init_grep_defaults(void)
> color_set(opt->color_selected, "");
> color_set(opt->color_sep, GIT_COLOR_CYAN);
> opt->color = -1;
> +#ifndef NO_PTHREADS
> + opt->num_threads = GREP_NUM_THREADS_DEFAULT;
> +#endif /* !NO_PTHREADS */
> }
>
> static int parse_pattern_type_arg(const char *opt, const char *arg)
> @@ -124,6 +127,14 @@ int grep_config(const char *var, const char *value, void *cb)
> return config_error_nonbool(var);
> return color_parse(value, color);
> }
> +
> +#ifndef NO_PTHREADS
> + if (!strcmp(var, "grep.threadsnum")) {
> + int threads = git_config_int(var, value);
> + opt->num_threads = (threads >= 0) ? threads : GREP_NUM_THREADS_DEFAULT;
> + return 0;
> + }
> +#endif /* !NO_PTHREADS */
> return 0;
> }
>
> @@ -150,6 +161,10 @@ void grep_init(struct grep_opt *opt, const char *prefix)
> opt->pathname = def->pathname;
> opt->regflags = def->regflags;
> opt->relative = def->relative;
> +#ifndef NO_PTHREADS
> + if(!opt->num_threads)
> + opt->num_threads = def->num_threads;
> +#endif /* !NO_PTHREADS */
>
> color_set(opt->color_context, def->color_context);
> color_set(opt->color_filename, def->color_filename);
> diff --git a/grep.h b/grep.h
> index 95f197a..e4a296b 100644
> --- a/grep.h
> +++ b/grep.h
> @@ -132,6 +132,10 @@ struct grep_opt {
> unsigned pre_context;
> unsigned post_context;
> unsigned last_shown;
> +#ifndef NO_PTHREADS
> +#define GREP_NUM_THREADS_DEFAULT 8
> + unsigned num_threads;
> +#endif /* !NO_PTHREADS */
> int show_hunk_mark;
> int file_break;
> int heading;
> --
> 2.6.2.281.gd4b1c9f
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