[Lustre-discuss] Lustre 2.0 client cache size

[Alex Kulyavtsev]

We used POSIX_FADV_DONTNEED in distributed iozone test to clear cache  
on slave client after initial write and before client reads back same  
data.  It helped to see real data rates instead of unrealistically  
high read rate due do cacheing. Perhaps it was non-lustre (NFS) file  
server.

If you do scripting, small executable like
   http://www.citi.umich.edu/projects/asci/benchmarks.html  (scroll  
down to Clearcache)
can be called after "cp" or "dd."
Alex.


On Mar 19, 2011, at 12:47 AM, Jay wrote:

> After checking 2.6.35 kernel source code, POSIX_FADV_NOREUSE  
> actually doesn't do anything. So I don't know how it helps. Probably  
> we should do POSIX_FADV_DONTNEED after reading?
>
> Jay

> On Mar 18, 2011, at 1:07 AM, DEGREMONT Aurelien wrote:
>
>>> ... snip...
>> Hmm... I do not want to patch 'cp' or 'dd' :)