Make number of git-grep worker threads a configuration parameter.
According to several tests on systems with different number of CPU cores
the hard-coded number of 8 threads is not optimal for all systems:
tuning this parameter can significantly speed up grep performance.
Signed-off-by: Victor Leschuk <vleschuk@xxxxxxxxxxxxxxxx>
---
Documentation/config.txt | 4 +++
Documentation/git-grep.txt | 9 ++++++
builtin/grep.c | 56 ++++++++++++++++++++++++----------
contrib/completion/git-completion.bash | 1 +
4 files changed, 54 insertions(+), 16 deletions(-)
diff --git a/Documentation/config.txt b/Documentation/config.txt
index 391a0c3..1dd2a61 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.threads::
+ Number of grep worker threads, use it to tune up performance on
+ multicore machines. Default value is 8. Set to 0 to disable threading.
+
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..e766596 100644
--- a/Documentation/git-grep.txt
+++ b/Documentation/git-grep.txt
@@ -23,6 +23,7 @@ SYNOPSIS
[--break] [--heading] [-p | --show-function]
[-A <post-context>] [-B <pre-context>] [-C <context>]
[-W | --function-context]
+ [--threads <num>]
[-f <file>] [-e] <pattern>
[--and|--or|--not|(|)|-e <pattern>...]
[ [--[no-]exclude-standard] [--cached | --no-index | --untracked] | <tree>...]
@@ -53,6 +54,10 @@ grep.extendedRegexp::
option is ignored when the 'grep.patternType' option is set to a value
other than 'default'.
+grep.threads::
+ Number of grep worker threads, use it to tune up performance on
+ multicore machines. Default value is 8. Set to 0 to disable threading.
+
grep.fullName::
If set to true, enable '--full-name' option by default.
@@ -227,6 +232,10 @@ OPTIONS
effectively showing the whole function in which the match was
found.
+--threads <num>::
+ Set number of worker threads to <num>. Default is 8.
+ Set to 0 to disable threading.
+
-f <file>::
Read patterns from <file>, one per line.
diff --git a/builtin/grep.c b/builtin/grep.c
index d04f440..694553e 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -24,11 +24,11 @@ static char const * const grep_usage[] = {
NULL
};
-static int use_threads = 1;
+#define GREP_NUM_THREADS_DEFAULT 8
+static int num_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
@@ -63,13 +63,13 @@ static pthread_mutex_t grep_mutex;
static inline void grep_lock(void)
{
- if (use_threads)
+ if (num_threads)
pthread_mutex_lock(&grep_mutex);
}
static inline void grep_unlock(void)
{
- if (use_threads)
+ if (num_threads)
pthread_mutex_unlock(&grep_mutex);
}
@@ -206,7 +206,8 @@ static void start_threads(struct grep_opt *opt)
strbuf_init(&todo[i].out, 0);
}
- for (i = 0; i < ARRAY_SIZE(threads); i++) {
+ threads = xcalloc(num_threads, sizeof(pthread_t));
+ for (i = 0; i < num_threads; i++) {
int err;
struct grep_opt *o = grep_opt_dup(opt);
o->output = strbuf_out;
@@ -238,12 +239,14 @@ static int wait_all(void)
pthread_cond_broadcast(&cond_add);
grep_unlock();
- for (i = 0; i < ARRAY_SIZE(threads); i++) {
+ for (i = 0; i < 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);
@@ -262,10 +265,22 @@ static int wait_all(void)
}
#endif
+static int grep_threads_config(const char *var, const char *value, void *cb)
+{
+ if (!strcmp(var, "grep.threads")) {
+ num_threads = git_config_int(var, value);
+ if (num_threads < 0)
+ die("Invalid number of threads specified (%d)", num_threads);
+ }
+ return 0;
+}
+
static int grep_cmd_config(const char *var, const char *value, void *cb)
{
int st = grep_config(var, value, cb);
- if (git_color_default_config(var, value, cb) < 0)
+ if (grep_threads_config(var, value, cb) < 0)
+ st = -1;
+ else if (git_color_default_config(var, value, cb) < 0)
st = -1;
return st;
}
@@ -294,7 +309,7 @@ static int grep_sha1(struct grep_opt *opt, const unsigned char *sha1,
}
#ifndef NO_PTHREADS
- if (use_threads) {
+ if (num_threads) {
add_work(opt, GREP_SOURCE_SHA1, pathbuf.buf, path, sha1);
strbuf_release(&pathbuf);
return 0;
@@ -323,7 +338,7 @@ static int grep_file(struct grep_opt *opt, const char *filename)
strbuf_addstr(&buf, filename);
#ifndef NO_PTHREADS
- if (use_threads) {
+ if (num_threads) {
add_work(opt, GREP_SOURCE_FILE, buf.buf, filename, filename);
strbuf_release(&buf);
return 0;
@@ -702,6 +717,8 @@ 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")),
+ OPT_INTEGER(0, "threads", &num_threads,
+ N_("use <n> worker threads")),
OPT_NUMBER_CALLBACK(&opt, N_("shortcut for -C NUM"),
context_callback),
OPT_BOOL('p', "show-function", &opt.funcname,
@@ -801,7 +818,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
opt.output_priv = &path_list;
opt.output = append_path;
string_list_append(&path_list, show_in_pager);
- use_threads = 0;
+ num_threads = 0;
}
if (!opt.pattern_list)
@@ -832,14 +849,21 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
}
#ifndef NO_PTHREADS
- if (list.nr || cached || online_cpus() == 1)
- use_threads = 0;
+ if (list.nr || cached) {
+ num_threads = 0; /* Can not multi-thread object lookup */
+ }
+ else if (num_threads < 0 && online_cpus() <= 1) {
+ num_threads = 0; /* User didn't set threading option and we have <= 1 of hardware cores */
+ }
+ else if (num_threads < 0) {
+ num_threads = GREP_NUM_THREADS_DEFAULT;
+ }
#else
- use_threads = 0;
+ num_threads = 0;
#endif
#ifndef NO_PTHREADS
- if (use_threads) {
+ if (num_threads) {
if (!(opt.name_only || opt.unmatch_name_only || opt.count)
&& (opt.pre_context || opt.post_context ||
opt.file_break || opt.funcbody))
@@ -909,7 +933,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
hit = grep_objects(&opt, &pathspec, &list);
}
- if (use_threads)
+ if (num_threads)
hit |= wait_all();
if (hit && show_in_pager)
run_pager(&opt, prefix);
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 482ca84..390d9c0 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
--files-with-matches --name-only
--files-without-match
--max-depth
--
2.6.2.308.g3b8f10c.dirty
--
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