Let's keep thread stuff close together if possible.  And in this case, 
this even reduces the #ifdef noise, and allows for skipping the 
autodetection altogether if delta search is not needed (like with a pure 
clone).

Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
---

> 2009/11/4 Nicolas Pitre <nico@fluxnic.net>:
> >> @@ -2327,6 +2354,8 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
> >>  #ifdef THREADED_DELTA_SEARCH
> >>       if (!delta_search_threads)      /* --threads=0 means autodetect */
> >>               delta_search_threads = online_cpus();
> >> +
> >> +     init_threaded_delta_search();
> >
> > What about doing this at the beginning of ll_find_deltas() instead?
> > And similarly for cleanup_threaded_delta_search(): call it right before
> > leaving ll_find_deltas().  This way thread issues would remain more
> > localized.  In fact I'd move the whole thing above in ll_find_deltas()
> > as well (separately from this patch though).

So here it is.

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index 02f9246..4c91e94 100644
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -1629,6 +1629,8 @@ static void ll_find_deltas(struct object_entry **list, unsigned list_size,
 	struct thread_params *p;
 	int i, ret, active_threads = 0;
 
+	if (!delta_search_threads)	/* --threads=0 means autodetect */
+		delta_search_threads = online_cpus();
 	if (delta_search_threads <= 1) {
 		find_deltas(list, &list_size, window, depth, processed);
 		return;
@@ -2324,11 +2326,6 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 	if (keep_unreachable && unpack_unreachable)
 		die("--keep-unreachable and --unpack-unreachable are incompatible.");
 
-#ifdef THREADED_DELTA_SEARCH
-	if (!delta_search_threads)	/* --threads=0 means autodetect */
-		delta_search_threads = online_cpus();
-#endif
-
 	prepare_packed_git();
 
 	if (progress)