Speedup init_disk_util() when dealing with many jobs
sysfs lookups can take quite a while, so check against last device
to avoid having to iterate through sysfs again.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/stat.c b/stat.c
index 34b2b6a..a8f2b02 100644
--- a/stat.c
+++ b/stat.c
@@ -11,6 +11,7 @@
static struct itimerval itimer;
static struct list_head disk_list = LIST_HEAD_INIT(disk_list);
+static dev_t last_dev;
/*
* Cheasy number->string conversion, complete with carry rounding error.
@@ -273,6 +274,17 @@
if (disk_util_exists(dev))
return;
+
+ /*
+ * for an fs without a device, we will repeatedly stat through
+ * sysfs which can take oodles of time for thousands of files. so
+ * cache the last lookup and compare with that before going through
+ * everything again.
+ */
+ if (dev == last_dev)
+ return;
+
+ last_dev = dev;
sprintf(foo, "/sys/block");
if (!find_block_dir(dev, foo))