[PATCH 2/2] Add core.threadedcheckout config option

[James Pickens <james.e.pickens@intel.com>]

Setting it to 'true' enables multi threaded checkout.  Default is false.
---
 Documentation/config.txt |    8 ++++++++
 cache.h                  |    1 +
 config.c                 |    5 +++++
 environment.c            |    3 +++
 unpack-trees.c           |    3 +++
 5 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 21ea165..22ac76b 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -422,6 +422,14 @@ relatively high IO latencies.  With this set to 'true', git will do the
 index comparison to the filesystem data in parallel, allowing
 overlapping IO's.
 
+core.threadedcheckout::
+	Enable parallel checkout for operations like 'git checkout'
++
+This can speed up operations like 'git clone' and 'git checkout' especially
+on filesystems like NFS that have relatively high IO latencies.  With this
+set to 'true', git will write the checked out files to disk in parallel,
+allowing overlapping IO's.
+
 alias.*::
 	Command aliases for the linkgit:git[1] command wrapper - e.g.
 	after defining "alias.last = cat-file commit HEAD", the invocation
diff --git a/cache.h b/cache.h
index 231c06d..0777597 100644
--- a/cache.h
+++ b/cache.h
@@ -512,6 +512,7 @@ extern size_t delta_base_cache_limit;
 extern int auto_crlf;
 extern int fsync_object_files;
 extern int core_preload_index;
+extern int core_threaded_checkout;
 
 enum safe_crlf {
 	SAFE_CRLF_FALSE = 0,
diff --git a/config.c b/config.c
index 790405a..819693e 100644
--- a/config.c
+++ b/config.c
@@ -495,6 +495,11 @@ static int git_default_core_config(const char *var, const char *value)
 		return 0;
 	}
 
+	if (!strcmp(var, "core.threadedcheckout")) {
+		core_threaded_checkout = git_config_bool(var, value);
+		return 0;
+	}
+
 	/* Add other config variables here and to Documentation/config.txt. */
 	return 0;
 }
diff --git a/environment.c b/environment.c
index e278bce..2450b65 100644
--- a/environment.c
+++ b/environment.c
@@ -46,6 +46,9 @@ enum rebase_setup_type autorebase = AUTOREBASE_NEVER;
 /* Parallel index stat data preload? */
 int core_preload_index = 0;
 
+/* Parallel checkout? */
+int core_threaded_checkout = 0;
+
 /* This is set by setup_git_dir_gently() and/or git_default_config() */
 char *git_work_tree_cfg;
 static char *work_tree;
diff --git a/unpack-trees.c b/unpack-trees.c
index 30b9862..635b7dc 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -165,6 +165,9 @@ static int threaded_checkout(struct index_state *index, int update, struct progr
 	struct thread_data data[MAX_PARALLEL];
 	int errs = 0;
 
+	if (!core_threaded_checkout)
+		return 0;
+
 	threads = index->cache_nr / THREAD_COST;
 	if (threads > MAX_PARALLEL)
 		threads = MAX_PARALLEL;
-- 
1.6.0.4.1116.gc5d7