[Lustre-discuss] RPC limitation

Oleg Drokin Oleg.Drokin at Sun.COM
Tue Mar 9 16:49:51 PST 2010


Hello!

   This only works if all the requests are for the same file, then it is done for you automatically
   (assuming that these are write requests and there is not sync in between. It's impossible to do
    for reads for obvious reason that read is a synchronous operation and by the time we do second
    read request first one must have completed and returned the data).

Bye,
    Oleg
On Mar 9, 2010, at 7:40 PM, Jeffrey Bennett wrote:

> Andreas and Oleg,
> 
> Sorry to bother you again.
> 
> Is there any way to "force" an RPC page size of 256kb and pack several 4kb random operations into a 256k page so the final throughput can increase?
> 
> Thanks
> 
> Jeffrey A. Bennett
> HPC Systems Engineer
> San Diego Supercomputer Center
> http://users.sdsc.edu/~jab
> 
> -----Original Message-----
> From: Andreas.Dilger at sun.com [mailto:Andreas.Dilger at sun.com] On Behalf Of Andreas Dilger
> Sent: Friday, March 05, 2010 2:05 AM
> To: Jeffrey Bennett
> Cc: Oleg.Drokin at Sun.COM; lustre-discuss at lists.lustre.org
> Subject: Re: [Lustre-discuss] One or two OSS, no difference?
> 
> On 2010-03-04, at 14:18, Jeffrey Bennett wrote:
>> I just noticed the sequential performance is ok, but the random IO  
>> (which is what I am measuring) is not. Is there any way to increase  
>> random IO performance on Lustre? We have LUNs that can provide  
>> around 250.000 random read 4kb IOPS but we are only seeing 3.000 to  
>> 10.000 on Lustre.
> 
> There is work currently underway to improve the SMP scaling  
> performance for the RPC handling layer in Lustre.  Currently that  
> limits the delivered RPC rate to 10-15k/sec or so.
> 




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