What is the significance of the numbers in the name of the flush processes for newer linux kernels?

Question

I am running kernel 2.6.33.7.

Previously, I was running v2.6.18.x. On 2.6.18, the flush processes were named pdflush.

After upgrading to 2.6.33.7, the flush processes have a format of "flush-:". For example, currently I see flush process "flush-8:32" popping up in top.

In doing a google search to try to determine an answer to this question, I saw examples of "flush-8:38", "flush-8:64" and "flush-253:0" just to name a few.

I understand what the flush process itself does, my question is what is the significance of the numbers on the end of the process name? What do they represent?

Thanks

Answer 1

Device numbers used to identify block devices. A kernel thread may be spawned to handle a particular device.

(On one of my systems, block devices are currently numbered as shown below. They may change from boot to boot or hotplug to hotplug.)

$ grep ^ /sys/class/block/*/dev
/sys/class/block/dm-0/dev:254:0
/sys/class/block/dm-1/dev:254:1
/sys/class/block/dm-2/dev:254:2
/sys/class/block/dm-3/dev:254:3
/sys/class/block/dm-4/dev:254:4
/sys/class/block/dm-5/dev:254:5
/sys/class/block/dm-6/dev:254:6
/sys/class/block/dm-7/dev:254:7
/sys/class/block/dm-8/dev:254:8
/sys/class/block/dm-9/dev:254:9
/sys/class/block/loop0/dev:7:0
/sys/class/block/loop1/dev:7:1
/sys/class/block/loop2/dev:7:2
/sys/class/block/loop3/dev:7:3
/sys/class/block/loop4/dev:7:4
/sys/class/block/loop5/dev:7:5
/sys/class/block/loop6/dev:7:6
/sys/class/block/loop7/dev:7:7
/sys/class/block/md0/dev:9:0
/sys/class/block/md1/dev:9:1
/sys/class/block/sda/dev:8:0
/sys/class/block/sda1/dev:8:1
/sys/class/block/sda2/dev:8:2
/sys/class/block/sdb/dev:8:16
/sys/class/block/sdb1/dev:8:17
/sys/class/block/sdb2/dev:8:18
/sys/class/block/sdc/dev:8:32
/sys/class/block/sdc1/dev:8:33
/sys/class/block/sdc2/dev:8:34
/sys/class/block/sdd/dev:8:48
/sys/class/block/sdd1/dev:8:49
/sys/class/block/sdd2/dev:8:50
/sys/class/block/sde/dev:8:64
/sys/class/block/sdf/dev:8:80
/sys/class/block/sdg/dev:8:96
/sys/class/block/sdh/dev:8:112
/sys/class/block/sdi/dev:8:128
/sys/class/block/sr0/dev:11:0
/sys/class/block/sr1/dev:11:1
/sys/class/block/sr2/dev:11:2