[Beowulf] scratch File system for small cluster

Joe Landman landman at scalableinformatics.com
Thu Sep 25 11:03:26 EDT 2008


Scott Atchley wrote:
> On Sep 25, 2008, at 10:19 AM, Joe Landman wrote:
> 
>> We have measured NFSoverRDMA speeds (on SDR IB at that) at 460 MB/s, 
>> on an RDMA adapter reporting 750 MB/s (in a 4x PCIe slot, so ~860 MB/s 
>> max is what we should expect for this).  Faster IB hardware should 
>> result in better performance, though you still have to walk through 
>> the various software stacks, and they ... remove efficiency ... (nice 
>> PC way to say that they slow things down a bit :( )
> 
> Joe,
> 
> Even though recent kernels allow rsize and wsize of 1 MB for TCP, 
> RPCRDMA only supports 32 KB. This will limit your throughput some 
> regardless of faster hardware.

I saw some messages to that effect a while ago (from you as I remember) 
on another list.

10 or more Gb network, and the RDMA version lets you do a spoonful of 
data at a time ... Do'h!


-- 
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: landman at scalableinformatics.com
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