dio: add I/O scheduler support

I/O scheduler information is stored in the key: {sched}

README

@@ -227,7 +227,8 @@ vicious.widgets.dio
   - provides I/O statistics for requested storage devices
   - takes the disk as an argument, i.e. "sda"
   - returns a table with string keys: {total_s}, {total_kb}, {total_mb},
-    {read_s}, {read_kb}, {read_mb}, {write_s}, {write_kb} and {write_mb}
+    {read_s}, {read_kb}, {read_mb}, {write_s}, {write_kb}, {write_mb}
+    and {sched}
 
 vicious.widgets.hddtemp
   - provides hard drive temperatures using the hddtemp daemon

dio.lua

@@ -26,6 +26,7 @@ local unit = { ["s"] = 1, ["kb"] = 2, ["mb"] = 2048 }
 local function worker(format, disk)
     local disk_lines = { [disk] = {} }
     local disk_stats = helpers.pathtotable("/sys/block/" .. disk)
+    local disk_queue = helpers.pathtotable("/sys/block/" .. disk .. "/queue")
 
     if disk_stats.stat then
         local match = string.gmatch(disk_stats.stat, "[%s]+([%d]+)")
@@ -58,6 +59,11 @@ local function worker(format, disk)
     helpers.uformat(disk_usage[disk], "write", diff_total[disk][7], unit)
     helpers.uformat(disk_usage[disk], "total", diff_total[disk][7] + diff_total[disk][3], unit)
 
+    -- Store I/O scheduler
+    if disk_queue.scheduler then
+        disk_usage[disk]["{sched}"] = string.gmatch(disk_queue.scheduler, "%[([%a]+)%]")
+    end
+
     return disk_usage[disk]
 end
 -- }}}