[Lustre-discuss] lustre and noatime option

[Adam Cassar]

The problem isn't with the RPC - its with the additional disk writes.

The single lrgest metadata performance gain we achieved was by changing 
the atime_diff parameter in /proc


Brian J. Murrell wrote:
> On Tue, 2008-04-29 at 13:09 -0600, Lundgren, Andrew wrote:
>   
>> I don't need to know the last access time on my files.  I looked
>> though the manual, but didn't find a reference  to noatime.  Does
>> lustre use that setting? (on the cl
>>
>> -- 
>>
>> Adam Cassar
>> ICT Manager
>> NetRegistry
>> -------------------------------------------------------
>> o:  02 9699 6099
>> f:  02 9699 6088
>> d:  02 9641 8609
>> -------------------------------------------------------
>>
>> Netregistry Pty Ltd
>> www.netregistry.com.au
>> PO Box 270 Broadway, NSW 2007
>> tel: +61 2 9699 6099  fax: +61 2 9699 608
>> ient and/or server) 
>>     
>
> I don't believe it does because...
>  
>   
>> On a file system that is read heavily, I would expect to see a
>> performance improvement by using that.  Is that true for lustre as
>> well?
>>     
>
> Lustre already handles atime in a pretty efficient manner.  Rather than
> disable it completely we update it "lazily".  What that means is that
> rather than sending immediate and explicit RPCs to update the atime we
> will delay sending them (for up to 5 seconds, tunable IIRC) and try to
> send atime updates "piggybacked" with other RPC traffic.
>
> b.
>
>   
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>   

-- 

Adam Cassar
ICT Manager
NetRegistry
-------------------------------------------------------
o:  02 9699 6099
f:  02 9699 6088
d:  02 9641 8609
-------------------------------------------------------

Netregistry Pty Ltd
www.netregistry.com.au
PO Box 270 Broadway, NSW 2007
tel: +61 2 9699 6099  fax: +61 2 9699 608