Re: [RFC][Resend] Make NFS-Client readahead tunable

[Martin Knoblauch]

Adding back LKML.


----- Original Message ----
> From: Jim Rees <rees@xxxxxxxxx>
> To: Martin Knoblauch <knobi@xxxxxxxxxxxx>
> Cc: linux-nfs list <linux-nfs@xxxxxxxxxxxxxxx>
> Sent: Wednesday, September 17, 2008 5:31:12 PM
> Subject: Re: [RFC][Resend] Make NFS-Client readahead tunable
> 
> Martin Knoblauch wrote:
> 
>    We never needed that in our case. But yes, would be trivial. The question
>    is, whether there should be a maximum, just as a safeguard.
> 
> Yes.  The default should be (RPC_DEF_SLOT_TABLE - 1), and the maximum should
> be max(xprt_udp_slot_table_entries, xprt_tcp_slot_table_entries) (maybe
> minus one).
> 

The default is NFS_MAX_READAHEAD, which is (RPC_DEF_SLOT_TABLE - 1). Incidentially, your suggested maximum seems to be the same on a default setup (minus one applied).

> I wonder if it would make sense to adjust NFS_MAX_READAHEAD when
> xprt_*_slot_table_entries is changed via sysctl.

I am not sure how useful/practical this is, as currently the ra_factor is applied at mount time.

Cheers
Martin

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