Am I right in assuming that if the io_tokens value is positive then I'm not actively being limited?

For example, on my idle machine:

io_count=25139840 io_rate=0 io_tokens=200000 token_refill=512 token_max=200000

Clearly I'm not doing much I/O and so no problems.

But if it says

io_count=25142137 io_rate=166 io_tokens=199933 token_refill=512 token_max=200000

then would the limiter kick in?

Can the io_rate ever go above token_refill?

In my sporadic checking I've never seen io_rate go above 300, but I just wanted to make sure I have the details correct in my own mind

_________________
Rgds
Stephen
(Linux user since kernel version 0.11)

Hi,

The io_rate can go over the refill rate, but if it does it for to long you will run out of tokens.

It is when you run out of io_tokens you will run into a problem.

The system works the same as iptables buckets

Adam

To clarify a little, you can do as much IO as you want as long as you have >0 tokens. When you get to 0, you run out, and you are limited to doing IO at a rate on average equal to refill rate,

Maybe it will also help to clear up what each number means:

io_count=25142137
I believe this is the total input/output your linode has done (since boot I think)

io_rate=166
This is how much input/output your Linode is currently doing per unit of time.

io_tokens=199933
This is basically your input/output buffer... If you're io_rate is above token_refill, this will slowly go down. If it reaches 0, then that's when your Linode starts to get limited, and you can only use token_refill tokens per unit of time.

token_refill=512
The rate at which your io_tokens buffer is refilled per unit of time.

token_max=200000
The max size of your i/o buffer.

So when I originally wrote "Am I right in assuming that if the io_tokens value is positive then I'm not actively being limited? " then I was correct and I'm doing just fine

Thanks!

_________________
Rgds

Stephen

(Linux user since kernel version 0.11)

That's kind of a yes and no answer. If your programming something that relies on that answer, then use the assumption that if io_tokens is greater than token_refill, _then_ your not actively being limited. Your Linode may have just been granted another token_refill tokens after being in the hole, in which case, your not in the free and clear just yet. Another way to tell is to look at your io_rate. If it's close to the same as token_refill, and your io_tokens bucket is pretty empty, then your being limited.

If your going to be making assumptions on this, your safest bet would be to say if your io_tokens is less than 10% of your token_max, then your using too much I/O.