[Lustre-discuss] Lustre 2.0 client cache size

Oleg Drokin green at whamcloud.com
Thu Mar 17 17:43:00 PDT 2011


Hello!

On Mar 17, 2011, at 5:44 PM, Andreas Dilger wrote:
>> I did not find if this was removed or this was partially included in 
>> Lustre 2.0.
>> What's the current status of this and how can I tell to my client to 
>> avoid caching too many data?
> The client VM usage was one of the areas that was completely rewritten by Nikita for 2.0, so it was likely this functionality was lost at that time.  I don't have any idea at this time how hard it would be to restore.

I wonder if the generic vm tunables could be used instead? I think that was the original plan.

>> Those clients do a lot of read and write in Lustre filesystems but 
>> thoses files will not be re-read soon, so it is useless to fill memory 
>> with it. Moreover, when the client memory is full, Lustre performance 
>> are really impacted.
> It may be possible to use fadvise(FADV_NOREUSE) from the application to cause the VM to discard these pages after the first use.

Yes, that would totally make sense to do regardless of other methods.

Bye,
    Oleg


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