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udevd: avoid overhead of calling rmdir on non-empty directories

PATCH In review Alan Jenkins 2 participants 2 messages Oct 18, 2008

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Alan Jenkins

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#0 lore raw

PATCH 1/1 udevd: avoid overhead of calling rmdir on non-empty directories

Unfortunately the linux rmdir implementation unhashes the dentry even when the directory is not removed. This is apparently by design (for filesystems that don't allow deleting open files).

Results from time(1) and oprofile follow.

Before:

0.35user 0.90system

samples  %        image name               symbol name                                                                    
608       9.6738  vmlinux                  shrink_dcache_parent                                                           
293       4.6619  vmlinux                  copy_page_c                                                                    
271       4.3119  vmlinux                  copy_page_range                                                                
257       4.0891  udevd                    udev_rules_iter_next

After:

0.31user 0.67system

samples  %        image name               symbol name
361       5.0419  vmlinux                  copy_page_range
322       4.4972  udevd                    udev_rules_iter_next
300       4.1899  vmlinux                  copy_page_c
Signed-off-by Alan Jenkins <[email protected]>
udev/udevd.c +10 -6
index 576f9e8..4b0c2e8 100644
@@ -109,8 +109,8 @@ static void export_event_state(struct udev_event *event, enum event_state state)
 
 	switch (state) {
 	case EVENT_QUEUED:
-		unlink(filename_failed);
-		delete_path(event->udev, filename_failed);
+		if(unlink(filename_failed) = 0)
+			delete_path(event->udev, filename_failed);
 		create_path(event->udev, filename);
 		udev_selinux_setfscreatecon(event->udev, filename, S_IFLNK);
 		symlink(udev_device_get_devpath(event->dev), filename);

@@ -131,12 +131,15 @@ static void export_event_state(struct udev_event *event, enum event_state state)
 				info(event->udev, "renamed devpath, moved failed state of '%s' to %s'\n",
 				     udev_device_get_devpath_old(event->dev), udev_device_get_devpath(event->dev));
 		} else {
-			unlink(filename_failed);
-			delete_path(event->udev, filename_failed);
+			if (unlink(filename_failed) = 0)
+				delete_path(event->udev, filename_failed);
 		}
 
 		unlink(filename);
-		delete_path(event->udev, filename);
+
+		/* clean up possibly empty queue directory */
+		if (udev_list_is_empty(&exec_list) && udev_list_is_empty(&running_list))
+			delete_path(event->udev, filename);
 		break;
 	case EVENT_FAILED:
 		/* move failed event to the failed directory */

@@ -144,7 +147,8 @@ static void export_event_state(struct udev_event *event, enum event_state state)
 		rename(filename, filename_failed);
 
 		/* clean up possibly empty queue directory */
-		delete_path(event->udev, filename);
+		if (udev_list_is_empty(&exec_list) && udev_list_is_empty(&running_list))
+			delete_path(event->udev, filename);
 		break;
 	}
#1 lore raw
Quoted 11 lines · Alan Jenkins

Unfortunately the linux rmdir implementation unhashes the dentry even when the directory is not removed. This is apparently by design (for filesystems that don't allow deleting open files).

Results from time(1) and oprofile follow.

Before:
0.35user 0.90system

After:
0.31user 0.67system

Nice! Applied.

Thanks,
Kay