FIX make readwrite query all my devices

drawing/ReadWrite.lua

@@ -1,12 +1,20 @@
-local Util		= require 'Util'
-local Common	= require 'Common'
+local Util = require 'Util'
+local Common = require 'Common'
 local Geometry = require 'Geometry'
 
 return function(update_freq)
    local PLOT_SEC_BREAK = 20
    local PLOT_HEIGHT = 56
+   local DEVICES = {'sda', 'nvme0n1'}
 
-   local __tonumber 	= tonumber
+   -- the sector size of any block device in linux is 512 bytes
+   -- see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/types.h?id=v4.4-rc6#n121
+   local BLOCK_SIZE_BYTES = 512
+
+   -- fields 3 and 7 (sectors read and written)
+   local RW_REGEX = '%s+%d+%s+%d+%s+(%d+)%s+%d+%s+%d+%s+%d+%s+(%d+)'
+
+   local __tonumber = tonumber
    local __string_match = string.match
    local __math_floor = math.floor
 
@@ -61,21 +69,25 @@ return function(update_freq)
    -----------------------------------------------------------------------------
    -- update function
 
-   -- TODO add more devices to this
-   local BLOCK_SIZE_BYTES = 512
-   local STAT_FILE = '/sys/block/sda/stat'
+   local DEVICE_PATHS = {}
+   for i = 1, #DEVICES do
+      DEVICE_PATHS[i] = string.format('/sys/block/%s/stat', DEVICES[i])
+   end
 
-   -- fields 3 and 7 (sectors read and written)
-   local RW_REGEX = '%s+%d+%s+%d+%s+(%d+)%s+%d+%s+%d+%s+%d+%s+(%d+)'
-
-   local read_stat_file = function()
-      local bytes_r, bytes_w = __string_match(Util.read_file(STAT_FILE), RW_REGEX)
-      return __tonumber(bytes_r) * BLOCK_SIZE_BYTES, __tonumber(bytes_w) * BLOCK_SIZE_BYTES
+   local read_devices = function()
+      local read_bytes = 0
+      local write_bytes = 0
+      for _, path in pairs(DEVICE_PATHS) do
+         local r, w = __string_match(Util.read_file(path), RW_REGEX)
+         read_bytes = read_bytes + __tonumber(r)
+         write_bytes = write_bytes + __tonumber(w)
+      end
+      return read_bytes * BLOCK_SIZE_BYTES, write_bytes * BLOCK_SIZE_BYTES
    end
 
    reads.byte_cnt = 0
    writes.byte_cnt = 0
-   reads.prev_byte_cnt, writes.prev_byte_cnt = read_stat_file()
+   reads.prev_byte_cnt, writes.prev_byte_cnt = read_devices()
 
    local update_stat = function(cr, stat, byte_cnt)
       local delta_bytes = byte_cnt - stat.prev_byte_cnt
@@ -90,7 +102,7 @@ return function(update_freq)
    end
 
    local update = function(cr)
-      local read_byte_cnt, write_byte_cnt = read_stat_file()
+      local read_byte_cnt, write_byte_cnt = read_devices()
       update_stat(cr, reads, read_byte_cnt)
       update_stat(cr, writes, write_byte_cnt)
    end