[erlang-questions] async threads

Jesper Louis Andersen jesper.louis.andersen@REDACTED
Mon Jun 10 11:13:01 CEST 2013

On Jun 10, 2013, at 10:56 AM, József Bérces <jozsef.berces@REDACTED> wrote:

> Hi,
> Is there a way to increase the async threads once the VM is running?
> I have a VM running already and but I do not want to have outage by restarting it. But it seems it waits for IO too much and I would like to see if increasing the async threads improves anything.

If you are talking about "iowait" in the linux kernel, then my guess would be "no improvement". Increasing async threads means that disk I/O won't block schedulers as much which can be beneficial if you have other processes that can do meaningful work without hitting the disk. But if you are ending up on the disk anyhow, then chances are you are just going to make things worse if there are more disk access.

I would use a tool to look at threads on the kernel level and look how many threads are currently blocked waiting for disk I/O.

Jesper Louis Andersen
  Erlang Solutions Ltd., Copenhagen

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