[Sheepdog] [PATCH 2/2] sheep: make gateway and io workers configurable

[Liu Yuan]

On 04/12/2012 11:30 PM, Christoph Hellwig wrote:

> On Thu, Apr 12, 2012 at 10:53:22PM +0800, Liu Yuan wrote:
>> From: Liu Yuan <tailai.ly at taobao.com>
>>
>> Most of the time one VM would issue multiple requests in one
>> go, so it would be useful to let users to decide how many workers
>> are useful if we have more than several VMs in single sheep node.
>>
>> In a large set nodes of cluster, every single node will get multiple
>> concurrent recovery IO requests, so it would be useful to have it as
>> configurable.
>>
>> default 4 workers for both and maximum 128.
> 
> I've seen in my benchmarking that's you'd want at least 64 to even
> saturate setup with single sata disks per daemon and a few dozens
> daemons, which means the default probably should be in that range.
> 


Hi Christoph,
   Thanks for your test numbers, I didn't expect this large threads to
run not-so-fast disk busy.
   How many cpus do you have on your box? I think this number has a
great dependency with the host available cpu number.

   I am not sure, I'd love to set 64 as default since our servers has a
considerable cpu cores, but for the boxes with limited cpus (Say, only
2), is 64 threads okay for them too(Do not waste memory resource for
unnecessary task_struct)?

Thanks,
Yuan